33024536ba
Patch series "memory tiering: hot page selection", v4.
To optimize page placement in a memory tiering system with NUMA balancing,
the hot pages in the slow memory nodes need to be identified.
Essentially, the original NUMA balancing implementation selects the mostly
recently accessed (MRU) pages to promote. But this isn't a perfect
algorithm to identify the hot pages. Because the pages with quite low
access frequency may be accessed eventually given the NUMA balancing page
table scanning period could be quite long (e.g. 60 seconds). So in this
patchset, we implement a new hot page identification algorithm based on
the latency between NUMA balancing page table scanning and hint page
fault. Which is a kind of mostly frequently accessed (MFU) algorithm.
In NUMA balancing memory tiering mode, if there are hot pages in slow
memory node and cold pages in fast memory node, we need to promote/demote
hot/cold pages between the fast and cold memory nodes.
A choice is to promote/demote as fast as possible. But the CPU cycles and
memory bandwidth consumed by the high promoting/demoting throughput will
hurt the latency of some workload because of accessing inflating and slow
memory bandwidth contention.
A way to resolve this issue is to restrict the max promoting/demoting
throughput. It will take longer to finish the promoting/demoting. But
the workload latency will be better. This is implemented in this patchset
as the page promotion rate limit mechanism.
The promotion hot threshold is workload and system configuration
dependent. So in this patchset, a method to adjust the hot threshold
automatically is implemented. The basic idea is to control the number of
the candidate promotion pages to match the promotion rate limit.
We used the pmbench memory accessing benchmark tested the patchset on a
2-socket server system with DRAM and PMEM installed. The test results are
as follows,
pmbench score promote rate
(accesses/s) MB/s
------------- ------------
base 146887704.1 725.6
hot selection 165695601.2 544.0
rate limit 162814569.8 165.2
auto adjustment 170495294.0 136.9
From the results above,
With hot page selection patch [1/3], the pmbench score increases about
12.8%, and promote rate (overhead) decreases about 25.0%, compared with
base kernel.
With rate limit patch [2/3], pmbench score decreases about 1.7%, and
promote rate decreases about 69.6%, compared with hot page selection
patch.
With threshold auto adjustment patch [3/3], pmbench score increases about
4.7%, and promote rate decrease about 17.1%, compared with rate limit
patch.
Baolin helped to test the patchset with MySQL on a machine which contains
1 DRAM node (30G) and 1 PMEM node (126G).
sysbench /usr/share/sysbench/oltp_read_write.lua \
......
--tables=200 \
--table-size=1000000 \
--report-interval=10 \
--threads=16 \
--time=120
The tps can be improved about 5%.
This patch (of 3):
To optimize page placement in a memory tiering system with NUMA balancing,
the hot pages in the slow memory node need to be identified. Essentially,
the original NUMA balancing implementation selects the mostly recently
accessed (MRU) pages to promote. But this isn't a perfect algorithm to
identify the hot pages. Because the pages with quite low access frequency
may be accessed eventually given the NUMA balancing page table scanning
period could be quite long (e.g. 60 seconds). The most frequently
accessed (MFU) algorithm is better.
So, in this patch we implemented a better hot page selection algorithm.
Which is based on NUMA balancing page table scanning and hint page fault
as follows,
- When the page tables of the processes are scanned to change PTE/PMD
to be PROT_NONE, the current time is recorded in struct page as scan
time.
- When the page is accessed, hint page fault will occur. The scan
time is gotten from the struct page. And The hint page fault
latency is defined as
hint page fault time - scan time
The shorter the hint page fault latency of a page is, the higher the
probability of their access frequency to be higher. So the hint page
fault latency is a better estimation of the page hot/cold.
It's hard to find some extra space in struct page to hold the scan time.
Fortunately, we can reuse some bits used by the original NUMA balancing.
NUMA balancing uses some bits in struct page to store the page accessing
CPU and PID (referring to page_cpupid_xchg_last()). Which is used by the
multi-stage node selection algorithm to avoid to migrate pages shared
accessed by the NUMA nodes back and forth. But for pages in the slow
memory node, even if they are shared accessed by multiple NUMA nodes, as
long as the pages are hot, they need to be promoted to the fast memory
node. So the accessing CPU and PID information are unnecessary for the
slow memory pages. We can reuse these bits in struct page to record the
scan time. For the fast memory pages, these bits are used as before.
For the hot threshold, the default value is 1 second, which works well in
our performance test. All pages with hint page fault latency < hot
threshold will be considered hot.
It's hard for users to determine the hot threshold. So we don't provide a
kernel ABI to set it, just provide a debugfs interface for advanced users
to experiment. We will continue to work on a hot threshold automatic
adjustment mechanism.
The downside of the above method is that the response time to the workload
hot spot changing may be much longer. For example,
- A previous cold memory area becomes hot
- The hint page fault will be triggered. But the hint page fault
latency isn't shorter than the hot threshold. So the pages will
not be promoted.
- When the memory area is scanned again, maybe after a scan period,
the hint page fault latency measured will be shorter than the hot
threshold and the pages will be promoted.
To mitigate this, if there are enough free space in the fast memory node,
the hot threshold will not be used, all pages will be promoted upon the
hint page fault for fast response.
Thanks Zhong Jiang reported and tested the fix for a bug when disabling
memory tiering mode dynamically.
Link: https://lkml.kernel.org/r/20220713083954.34196-1-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20220713083954.34196-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Wei Xu <weixugc@google.com>
Cc: osalvador <osalvador@suse.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Zhong Jiang <zhongjiang-ali@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2644 lines
69 KiB
C
2644 lines
69 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Memory Migration functionality - linux/mm/migrate.c
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*
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* Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
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*
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* Page migration was first developed in the context of the memory hotplug
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* project. The main authors of the migration code are:
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*
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* IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
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* Hirokazu Takahashi <taka@valinux.co.jp>
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* Dave Hansen <haveblue@us.ibm.com>
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* Christoph Lameter
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*/
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#include <linux/migrate.h>
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#include <linux/export.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/pagemap.h>
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#include <linux/buffer_head.h>
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#include <linux/mm_inline.h>
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#include <linux/nsproxy.h>
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#include <linux/pagevec.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/topology.h>
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#include <linux/cpu.h>
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#include <linux/cpuset.h>
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#include <linux/writeback.h>
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#include <linux/mempolicy.h>
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#include <linux/vmalloc.h>
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#include <linux/security.h>
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#include <linux/backing-dev.h>
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#include <linux/compaction.h>
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#include <linux/syscalls.h>
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#include <linux/compat.h>
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#include <linux/hugetlb.h>
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#include <linux/hugetlb_cgroup.h>
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#include <linux/gfp.h>
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#include <linux/pfn_t.h>
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#include <linux/memremap.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/balloon_compaction.h>
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#include <linux/page_idle.h>
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#include <linux/page_owner.h>
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#include <linux/sched/mm.h>
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#include <linux/ptrace.h>
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#include <linux/oom.h>
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#include <linux/memory.h>
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#include <linux/random.h>
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#include <linux/sched/sysctl.h>
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#include <asm/tlbflush.h>
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#include <trace/events/migrate.h>
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#include "internal.h"
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int isolate_movable_page(struct page *page, isolate_mode_t mode)
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{
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const struct movable_operations *mops;
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/*
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* Avoid burning cycles with pages that are yet under __free_pages(),
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* or just got freed under us.
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*
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* In case we 'win' a race for a movable page being freed under us and
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* raise its refcount preventing __free_pages() from doing its job
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* the put_page() at the end of this block will take care of
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* release this page, thus avoiding a nasty leakage.
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*/
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if (unlikely(!get_page_unless_zero(page)))
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goto out;
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/*
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* Check PageMovable before holding a PG_lock because page's owner
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* assumes anybody doesn't touch PG_lock of newly allocated page
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* so unconditionally grabbing the lock ruins page's owner side.
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*/
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if (unlikely(!__PageMovable(page)))
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goto out_putpage;
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/*
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* As movable pages are not isolated from LRU lists, concurrent
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* compaction threads can race against page migration functions
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* as well as race against the releasing a page.
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*
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* In order to avoid having an already isolated movable page
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* being (wrongly) re-isolated while it is under migration,
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* or to avoid attempting to isolate pages being released,
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* lets be sure we have the page lock
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* before proceeding with the movable page isolation steps.
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*/
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if (unlikely(!trylock_page(page)))
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goto out_putpage;
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if (!PageMovable(page) || PageIsolated(page))
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goto out_no_isolated;
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mops = page_movable_ops(page);
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VM_BUG_ON_PAGE(!mops, page);
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if (!mops->isolate_page(page, mode))
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goto out_no_isolated;
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/* Driver shouldn't use PG_isolated bit of page->flags */
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WARN_ON_ONCE(PageIsolated(page));
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SetPageIsolated(page);
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unlock_page(page);
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return 0;
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out_no_isolated:
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unlock_page(page);
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out_putpage:
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put_page(page);
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out:
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return -EBUSY;
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}
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static void putback_movable_page(struct page *page)
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{
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const struct movable_operations *mops = page_movable_ops(page);
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mops->putback_page(page);
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ClearPageIsolated(page);
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}
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/*
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* Put previously isolated pages back onto the appropriate lists
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* from where they were once taken off for compaction/migration.
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*
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* This function shall be used whenever the isolated pageset has been
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* built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
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* and isolate_hugetlb().
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*/
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void putback_movable_pages(struct list_head *l)
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{
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struct page *page;
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struct page *page2;
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list_for_each_entry_safe(page, page2, l, lru) {
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if (unlikely(PageHuge(page))) {
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putback_active_hugepage(page);
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continue;
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}
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list_del(&page->lru);
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/*
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* We isolated non-lru movable page so here we can use
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* __PageMovable because LRU page's mapping cannot have
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* PAGE_MAPPING_MOVABLE.
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*/
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if (unlikely(__PageMovable(page))) {
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VM_BUG_ON_PAGE(!PageIsolated(page), page);
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lock_page(page);
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if (PageMovable(page))
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putback_movable_page(page);
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else
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ClearPageIsolated(page);
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unlock_page(page);
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put_page(page);
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} else {
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mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
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page_is_file_lru(page), -thp_nr_pages(page));
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putback_lru_page(page);
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}
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}
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}
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/*
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* Restore a potential migration pte to a working pte entry
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*/
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static bool remove_migration_pte(struct folio *folio,
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struct vm_area_struct *vma, unsigned long addr, void *old)
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{
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DEFINE_FOLIO_VMA_WALK(pvmw, old, vma, addr, PVMW_SYNC | PVMW_MIGRATION);
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while (page_vma_mapped_walk(&pvmw)) {
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rmap_t rmap_flags = RMAP_NONE;
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pte_t pte;
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swp_entry_t entry;
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struct page *new;
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unsigned long idx = 0;
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/* pgoff is invalid for ksm pages, but they are never large */
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if (folio_test_large(folio) && !folio_test_hugetlb(folio))
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idx = linear_page_index(vma, pvmw.address) - pvmw.pgoff;
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new = folio_page(folio, idx);
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#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
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/* PMD-mapped THP migration entry */
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if (!pvmw.pte) {
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VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) ||
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!folio_test_pmd_mappable(folio), folio);
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remove_migration_pmd(&pvmw, new);
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continue;
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}
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#endif
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folio_get(folio);
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pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot)));
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if (pte_swp_soft_dirty(*pvmw.pte))
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pte = pte_mksoft_dirty(pte);
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/*
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* Recheck VMA as permissions can change since migration started
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*/
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entry = pte_to_swp_entry(*pvmw.pte);
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if (is_writable_migration_entry(entry))
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pte = maybe_mkwrite(pte, vma);
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else if (pte_swp_uffd_wp(*pvmw.pte))
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pte = pte_mkuffd_wp(pte);
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if (folio_test_anon(folio) && !is_readable_migration_entry(entry))
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rmap_flags |= RMAP_EXCLUSIVE;
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if (unlikely(is_device_private_page(new))) {
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if (pte_write(pte))
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entry = make_writable_device_private_entry(
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page_to_pfn(new));
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else
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entry = make_readable_device_private_entry(
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page_to_pfn(new));
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pte = swp_entry_to_pte(entry);
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if (pte_swp_soft_dirty(*pvmw.pte))
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pte = pte_swp_mksoft_dirty(pte);
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if (pte_swp_uffd_wp(*pvmw.pte))
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pte = pte_swp_mkuffd_wp(pte);
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}
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#ifdef CONFIG_HUGETLB_PAGE
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if (folio_test_hugetlb(folio)) {
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unsigned int shift = huge_page_shift(hstate_vma(vma));
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pte = pte_mkhuge(pte);
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pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
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if (folio_test_anon(folio))
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hugepage_add_anon_rmap(new, vma, pvmw.address,
|
|
rmap_flags);
|
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else
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page_dup_file_rmap(new, true);
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set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
|
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} else
|
|
#endif
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{
|
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if (folio_test_anon(folio))
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page_add_anon_rmap(new, vma, pvmw.address,
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|
rmap_flags);
|
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else
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page_add_file_rmap(new, vma, false);
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set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
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}
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if (vma->vm_flags & VM_LOCKED)
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|
mlock_page_drain_local();
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trace_remove_migration_pte(pvmw.address, pte_val(pte),
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compound_order(new));
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|
|
|
/* No need to invalidate - it was non-present before */
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|
update_mmu_cache(vma, pvmw.address, pvmw.pte);
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}
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return true;
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}
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|
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/*
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|
* Get rid of all migration entries and replace them by
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* references to the indicated page.
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*/
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void remove_migration_ptes(struct folio *src, struct folio *dst, bool locked)
|
|
{
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = remove_migration_pte,
|
|
.arg = src,
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|
};
|
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|
|
if (locked)
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rmap_walk_locked(dst, &rwc);
|
|
else
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|
rmap_walk(dst, &rwc);
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|
}
|
|
|
|
/*
|
|
* Something used the pte of a page under migration. We need to
|
|
* get to the page and wait until migration is finished.
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* When we return from this function the fault will be retried.
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*/
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void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
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spinlock_t *ptl)
|
|
{
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|
pte_t pte;
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|
swp_entry_t entry;
|
|
|
|
spin_lock(ptl);
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|
pte = *ptep;
|
|
if (!is_swap_pte(pte))
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goto out;
|
|
|
|
entry = pte_to_swp_entry(pte);
|
|
if (!is_migration_entry(entry))
|
|
goto out;
|
|
|
|
migration_entry_wait_on_locked(entry, ptep, ptl);
|
|
return;
|
|
out:
|
|
pte_unmap_unlock(ptep, ptl);
|
|
}
|
|
|
|
void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
|
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unsigned long address)
|
|
{
|
|
spinlock_t *ptl = pte_lockptr(mm, pmd);
|
|
pte_t *ptep = pte_offset_map(pmd, address);
|
|
__migration_entry_wait(mm, ptep, ptl);
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}
|
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|
|
#ifdef CONFIG_HUGETLB_PAGE
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void __migration_entry_wait_huge(pte_t *ptep, spinlock_t *ptl)
|
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{
|
|
pte_t pte;
|
|
|
|
spin_lock(ptl);
|
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pte = huge_ptep_get(ptep);
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|
|
if (unlikely(!is_hugetlb_entry_migration(pte)))
|
|
spin_unlock(ptl);
|
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else
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migration_entry_wait_on_locked(pte_to_swp_entry(pte), NULL, ptl);
|
|
}
|
|
|
|
void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte)
|
|
{
|
|
spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), vma->vm_mm, pte);
|
|
|
|
__migration_entry_wait_huge(pte, ptl);
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}
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#endif
|
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|
|
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
|
|
void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd)
|
|
{
|
|
spinlock_t *ptl;
|
|
|
|
ptl = pmd_lock(mm, pmd);
|
|
if (!is_pmd_migration_entry(*pmd))
|
|
goto unlock;
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|
migration_entry_wait_on_locked(pmd_to_swp_entry(*pmd), NULL, ptl);
|
|
return;
|
|
unlock:
|
|
spin_unlock(ptl);
|
|
}
|
|
#endif
|
|
|
|
static int folio_expected_refs(struct address_space *mapping,
|
|
struct folio *folio)
|
|
{
|
|
int refs = 1;
|
|
if (!mapping)
|
|
return refs;
|
|
|
|
refs += folio_nr_pages(folio);
|
|
if (folio_test_private(folio))
|
|
refs++;
|
|
|
|
return refs;
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|
}
|
|
|
|
/*
|
|
* Replace the page in the mapping.
|
|
*
|
|
* The number of remaining references must be:
|
|
* 1 for anonymous pages without a mapping
|
|
* 2 for pages with a mapping
|
|
* 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
|
|
*/
|
|
int folio_migrate_mapping(struct address_space *mapping,
|
|
struct folio *newfolio, struct folio *folio, int extra_count)
|
|
{
|
|
XA_STATE(xas, &mapping->i_pages, folio_index(folio));
|
|
struct zone *oldzone, *newzone;
|
|
int dirty;
|
|
int expected_count = folio_expected_refs(mapping, folio) + extra_count;
|
|
long nr = folio_nr_pages(folio);
|
|
|
|
if (!mapping) {
|
|
/* Anonymous page without mapping */
|
|
if (folio_ref_count(folio) != expected_count)
|
|
return -EAGAIN;
|
|
|
|
/* No turning back from here */
|
|
newfolio->index = folio->index;
|
|
newfolio->mapping = folio->mapping;
|
|
if (folio_test_swapbacked(folio))
|
|
__folio_set_swapbacked(newfolio);
|
|
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
|
|
oldzone = folio_zone(folio);
|
|
newzone = folio_zone(newfolio);
|
|
|
|
xas_lock_irq(&xas);
|
|
if (!folio_ref_freeze(folio, expected_count)) {
|
|
xas_unlock_irq(&xas);
|
|
return -EAGAIN;
|
|
}
|
|
|
|
/*
|
|
* Now we know that no one else is looking at the folio:
|
|
* no turning back from here.
|
|
*/
|
|
newfolio->index = folio->index;
|
|
newfolio->mapping = folio->mapping;
|
|
folio_ref_add(newfolio, nr); /* add cache reference */
|
|
if (folio_test_swapbacked(folio)) {
|
|
__folio_set_swapbacked(newfolio);
|
|
if (folio_test_swapcache(folio)) {
|
|
folio_set_swapcache(newfolio);
|
|
newfolio->private = folio_get_private(folio);
|
|
}
|
|
} else {
|
|
VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio);
|
|
}
|
|
|
|
/* Move dirty while page refs frozen and newpage not yet exposed */
|
|
dirty = folio_test_dirty(folio);
|
|
if (dirty) {
|
|
folio_clear_dirty(folio);
|
|
folio_set_dirty(newfolio);
|
|
}
|
|
|
|
xas_store(&xas, newfolio);
|
|
|
|
/*
|
|
* Drop cache reference from old page by unfreezing
|
|
* to one less reference.
|
|
* We know this isn't the last reference.
|
|
*/
|
|
folio_ref_unfreeze(folio, expected_count - nr);
|
|
|
|
xas_unlock(&xas);
|
|
/* Leave irq disabled to prevent preemption while updating stats */
|
|
|
|
/*
|
|
* If moved to a different zone then also account
|
|
* the page for that zone. Other VM counters will be
|
|
* taken care of when we establish references to the
|
|
* new page and drop references to the old page.
|
|
*
|
|
* Note that anonymous pages are accounted for
|
|
* via NR_FILE_PAGES and NR_ANON_MAPPED if they
|
|
* are mapped to swap space.
|
|
*/
|
|
if (newzone != oldzone) {
|
|
struct lruvec *old_lruvec, *new_lruvec;
|
|
struct mem_cgroup *memcg;
|
|
|
|
memcg = folio_memcg(folio);
|
|
old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat);
|
|
new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat);
|
|
|
|
__mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr);
|
|
__mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr);
|
|
if (folio_test_swapbacked(folio) && !folio_test_swapcache(folio)) {
|
|
__mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
|
|
__mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
|
|
}
|
|
#ifdef CONFIG_SWAP
|
|
if (folio_test_swapcache(folio)) {
|
|
__mod_lruvec_state(old_lruvec, NR_SWAPCACHE, -nr);
|
|
__mod_lruvec_state(new_lruvec, NR_SWAPCACHE, nr);
|
|
}
|
|
#endif
|
|
if (dirty && mapping_can_writeback(mapping)) {
|
|
__mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr);
|
|
__mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr);
|
|
__mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr);
|
|
__mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr);
|
|
}
|
|
}
|
|
local_irq_enable();
|
|
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
EXPORT_SYMBOL(folio_migrate_mapping);
|
|
|
|
/*
|
|
* The expected number of remaining references is the same as that
|
|
* of folio_migrate_mapping().
|
|
*/
|
|
int migrate_huge_page_move_mapping(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src)
|
|
{
|
|
XA_STATE(xas, &mapping->i_pages, folio_index(src));
|
|
int expected_count;
|
|
|
|
xas_lock_irq(&xas);
|
|
expected_count = 2 + folio_has_private(src);
|
|
if (!folio_ref_freeze(src, expected_count)) {
|
|
xas_unlock_irq(&xas);
|
|
return -EAGAIN;
|
|
}
|
|
|
|
dst->index = src->index;
|
|
dst->mapping = src->mapping;
|
|
|
|
folio_get(dst);
|
|
|
|
xas_store(&xas, dst);
|
|
|
|
folio_ref_unfreeze(src, expected_count - 1);
|
|
|
|
xas_unlock_irq(&xas);
|
|
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
|
|
/*
|
|
* Copy the flags and some other ancillary information
|
|
*/
|
|
void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
|
|
{
|
|
int cpupid;
|
|
|
|
if (folio_test_error(folio))
|
|
folio_set_error(newfolio);
|
|
if (folio_test_referenced(folio))
|
|
folio_set_referenced(newfolio);
|
|
if (folio_test_uptodate(folio))
|
|
folio_mark_uptodate(newfolio);
|
|
if (folio_test_clear_active(folio)) {
|
|
VM_BUG_ON_FOLIO(folio_test_unevictable(folio), folio);
|
|
folio_set_active(newfolio);
|
|
} else if (folio_test_clear_unevictable(folio))
|
|
folio_set_unevictable(newfolio);
|
|
if (folio_test_workingset(folio))
|
|
folio_set_workingset(newfolio);
|
|
if (folio_test_checked(folio))
|
|
folio_set_checked(newfolio);
|
|
/*
|
|
* PG_anon_exclusive (-> PG_mappedtodisk) is always migrated via
|
|
* migration entries. We can still have PG_anon_exclusive set on an
|
|
* effectively unmapped and unreferenced first sub-pages of an
|
|
* anonymous THP: we can simply copy it here via PG_mappedtodisk.
|
|
*/
|
|
if (folio_test_mappedtodisk(folio))
|
|
folio_set_mappedtodisk(newfolio);
|
|
|
|
/* Move dirty on pages not done by folio_migrate_mapping() */
|
|
if (folio_test_dirty(folio))
|
|
folio_set_dirty(newfolio);
|
|
|
|
if (folio_test_young(folio))
|
|
folio_set_young(newfolio);
|
|
if (folio_test_idle(folio))
|
|
folio_set_idle(newfolio);
|
|
|
|
/*
|
|
* Copy NUMA information to the new page, to prevent over-eager
|
|
* future migrations of this same page.
|
|
*/
|
|
cpupid = page_cpupid_xchg_last(&folio->page, -1);
|
|
/*
|
|
* For memory tiering mode, when migrate between slow and fast
|
|
* memory node, reset cpupid, because that is used to record
|
|
* page access time in slow memory node.
|
|
*/
|
|
if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) {
|
|
bool f_toptier = node_is_toptier(page_to_nid(&folio->page));
|
|
bool t_toptier = node_is_toptier(page_to_nid(&newfolio->page));
|
|
|
|
if (f_toptier != t_toptier)
|
|
cpupid = -1;
|
|
}
|
|
page_cpupid_xchg_last(&newfolio->page, cpupid);
|
|
|
|
folio_migrate_ksm(newfolio, folio);
|
|
/*
|
|
* Please do not reorder this without considering how mm/ksm.c's
|
|
* get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
|
|
*/
|
|
if (folio_test_swapcache(folio))
|
|
folio_clear_swapcache(folio);
|
|
folio_clear_private(folio);
|
|
|
|
/* page->private contains hugetlb specific flags */
|
|
if (!folio_test_hugetlb(folio))
|
|
folio->private = NULL;
|
|
|
|
/*
|
|
* If any waiters have accumulated on the new page then
|
|
* wake them up.
|
|
*/
|
|
if (folio_test_writeback(newfolio))
|
|
folio_end_writeback(newfolio);
|
|
|
|
/*
|
|
* PG_readahead shares the same bit with PG_reclaim. The above
|
|
* end_page_writeback() may clear PG_readahead mistakenly, so set the
|
|
* bit after that.
|
|
*/
|
|
if (folio_test_readahead(folio))
|
|
folio_set_readahead(newfolio);
|
|
|
|
folio_copy_owner(newfolio, folio);
|
|
|
|
if (!folio_test_hugetlb(folio))
|
|
mem_cgroup_migrate(folio, newfolio);
|
|
}
|
|
EXPORT_SYMBOL(folio_migrate_flags);
|
|
|
|
void folio_migrate_copy(struct folio *newfolio, struct folio *folio)
|
|
{
|
|
folio_copy(newfolio, folio);
|
|
folio_migrate_flags(newfolio, folio);
|
|
}
|
|
EXPORT_SYMBOL(folio_migrate_copy);
|
|
|
|
/************************************************************
|
|
* Migration functions
|
|
***********************************************************/
|
|
|
|
/**
|
|
* migrate_folio() - Simple folio migration.
|
|
* @mapping: The address_space containing the folio.
|
|
* @dst: The folio to migrate the data to.
|
|
* @src: The folio containing the current data.
|
|
* @mode: How to migrate the page.
|
|
*
|
|
* Common logic to directly migrate a single LRU folio suitable for
|
|
* folios that do not use PagePrivate/PagePrivate2.
|
|
*
|
|
* Folios are locked upon entry and exit.
|
|
*/
|
|
int migrate_folio(struct address_space *mapping, struct folio *dst,
|
|
struct folio *src, enum migrate_mode mode)
|
|
{
|
|
int rc;
|
|
|
|
BUG_ON(folio_test_writeback(src)); /* Writeback must be complete */
|
|
|
|
rc = folio_migrate_mapping(mapping, dst, src, 0);
|
|
|
|
if (rc != MIGRATEPAGE_SUCCESS)
|
|
return rc;
|
|
|
|
if (mode != MIGRATE_SYNC_NO_COPY)
|
|
folio_migrate_copy(dst, src);
|
|
else
|
|
folio_migrate_flags(dst, src);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
EXPORT_SYMBOL(migrate_folio);
|
|
|
|
#ifdef CONFIG_BLOCK
|
|
/* Returns true if all buffers are successfully locked */
|
|
static bool buffer_migrate_lock_buffers(struct buffer_head *head,
|
|
enum migrate_mode mode)
|
|
{
|
|
struct buffer_head *bh = head;
|
|
|
|
/* Simple case, sync compaction */
|
|
if (mode != MIGRATE_ASYNC) {
|
|
do {
|
|
lock_buffer(bh);
|
|
bh = bh->b_this_page;
|
|
|
|
} while (bh != head);
|
|
|
|
return true;
|
|
}
|
|
|
|
/* async case, we cannot block on lock_buffer so use trylock_buffer */
|
|
do {
|
|
if (!trylock_buffer(bh)) {
|
|
/*
|
|
* We failed to lock the buffer and cannot stall in
|
|
* async migration. Release the taken locks
|
|
*/
|
|
struct buffer_head *failed_bh = bh;
|
|
bh = head;
|
|
while (bh != failed_bh) {
|
|
unlock_buffer(bh);
|
|
bh = bh->b_this_page;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
return true;
|
|
}
|
|
|
|
static int __buffer_migrate_folio(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode,
|
|
bool check_refs)
|
|
{
|
|
struct buffer_head *bh, *head;
|
|
int rc;
|
|
int expected_count;
|
|
|
|
head = folio_buffers(src);
|
|
if (!head)
|
|
return migrate_folio(mapping, dst, src, mode);
|
|
|
|
/* Check whether page does not have extra refs before we do more work */
|
|
expected_count = folio_expected_refs(mapping, src);
|
|
if (folio_ref_count(src) != expected_count)
|
|
return -EAGAIN;
|
|
|
|
if (!buffer_migrate_lock_buffers(head, mode))
|
|
return -EAGAIN;
|
|
|
|
if (check_refs) {
|
|
bool busy;
|
|
bool invalidated = false;
|
|
|
|
recheck_buffers:
|
|
busy = false;
|
|
spin_lock(&mapping->private_lock);
|
|
bh = head;
|
|
do {
|
|
if (atomic_read(&bh->b_count)) {
|
|
busy = true;
|
|
break;
|
|
}
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
if (busy) {
|
|
if (invalidated) {
|
|
rc = -EAGAIN;
|
|
goto unlock_buffers;
|
|
}
|
|
spin_unlock(&mapping->private_lock);
|
|
invalidate_bh_lrus();
|
|
invalidated = true;
|
|
goto recheck_buffers;
|
|
}
|
|
}
|
|
|
|
rc = folio_migrate_mapping(mapping, dst, src, 0);
|
|
if (rc != MIGRATEPAGE_SUCCESS)
|
|
goto unlock_buffers;
|
|
|
|
folio_attach_private(dst, folio_detach_private(src));
|
|
|
|
bh = head;
|
|
do {
|
|
set_bh_page(bh, &dst->page, bh_offset(bh));
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
if (mode != MIGRATE_SYNC_NO_COPY)
|
|
folio_migrate_copy(dst, src);
|
|
else
|
|
folio_migrate_flags(dst, src);
|
|
|
|
rc = MIGRATEPAGE_SUCCESS;
|
|
unlock_buffers:
|
|
if (check_refs)
|
|
spin_unlock(&mapping->private_lock);
|
|
bh = head;
|
|
do {
|
|
unlock_buffer(bh);
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* buffer_migrate_folio() - Migration function for folios with buffers.
|
|
* @mapping: The address space containing @src.
|
|
* @dst: The folio to migrate to.
|
|
* @src: The folio to migrate from.
|
|
* @mode: How to migrate the folio.
|
|
*
|
|
* This function can only be used if the underlying filesystem guarantees
|
|
* that no other references to @src exist. For example attached buffer
|
|
* heads are accessed only under the folio lock. If your filesystem cannot
|
|
* provide this guarantee, buffer_migrate_folio_norefs() may be more
|
|
* appropriate.
|
|
*
|
|
* Return: 0 on success or a negative errno on failure.
|
|
*/
|
|
int buffer_migrate_folio(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode)
|
|
{
|
|
return __buffer_migrate_folio(mapping, dst, src, mode, false);
|
|
}
|
|
EXPORT_SYMBOL(buffer_migrate_folio);
|
|
|
|
/**
|
|
* buffer_migrate_folio_norefs() - Migration function for folios with buffers.
|
|
* @mapping: The address space containing @src.
|
|
* @dst: The folio to migrate to.
|
|
* @src: The folio to migrate from.
|
|
* @mode: How to migrate the folio.
|
|
*
|
|
* Like buffer_migrate_folio() except that this variant is more careful
|
|
* and checks that there are also no buffer head references. This function
|
|
* is the right one for mappings where buffer heads are directly looked
|
|
* up and referenced (such as block device mappings).
|
|
*
|
|
* Return: 0 on success or a negative errno on failure.
|
|
*/
|
|
int buffer_migrate_folio_norefs(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode)
|
|
{
|
|
return __buffer_migrate_folio(mapping, dst, src, mode, true);
|
|
}
|
|
#endif
|
|
|
|
int filemap_migrate_folio(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode)
|
|
{
|
|
int ret;
|
|
|
|
ret = folio_migrate_mapping(mapping, dst, src, 0);
|
|
if (ret != MIGRATEPAGE_SUCCESS)
|
|
return ret;
|
|
|
|
if (folio_get_private(src))
|
|
folio_attach_private(dst, folio_detach_private(src));
|
|
|
|
if (mode != MIGRATE_SYNC_NO_COPY)
|
|
folio_migrate_copy(dst, src);
|
|
else
|
|
folio_migrate_flags(dst, src);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
EXPORT_SYMBOL_GPL(filemap_migrate_folio);
|
|
|
|
/*
|
|
* Writeback a folio to clean the dirty state
|
|
*/
|
|
static int writeout(struct address_space *mapping, struct folio *folio)
|
|
{
|
|
struct writeback_control wbc = {
|
|
.sync_mode = WB_SYNC_NONE,
|
|
.nr_to_write = 1,
|
|
.range_start = 0,
|
|
.range_end = LLONG_MAX,
|
|
.for_reclaim = 1
|
|
};
|
|
int rc;
|
|
|
|
if (!mapping->a_ops->writepage)
|
|
/* No write method for the address space */
|
|
return -EINVAL;
|
|
|
|
if (!folio_clear_dirty_for_io(folio))
|
|
/* Someone else already triggered a write */
|
|
return -EAGAIN;
|
|
|
|
/*
|
|
* A dirty folio may imply that the underlying filesystem has
|
|
* the folio on some queue. So the folio must be clean for
|
|
* migration. Writeout may mean we lose the lock and the
|
|
* folio state is no longer what we checked for earlier.
|
|
* At this point we know that the migration attempt cannot
|
|
* be successful.
|
|
*/
|
|
remove_migration_ptes(folio, folio, false);
|
|
|
|
rc = mapping->a_ops->writepage(&folio->page, &wbc);
|
|
|
|
if (rc != AOP_WRITEPAGE_ACTIVATE)
|
|
/* unlocked. Relock */
|
|
folio_lock(folio);
|
|
|
|
return (rc < 0) ? -EIO : -EAGAIN;
|
|
}
|
|
|
|
/*
|
|
* Default handling if a filesystem does not provide a migration function.
|
|
*/
|
|
static int fallback_migrate_folio(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode)
|
|
{
|
|
if (folio_test_dirty(src)) {
|
|
/* Only writeback folios in full synchronous migration */
|
|
switch (mode) {
|
|
case MIGRATE_SYNC:
|
|
case MIGRATE_SYNC_NO_COPY:
|
|
break;
|
|
default:
|
|
return -EBUSY;
|
|
}
|
|
return writeout(mapping, src);
|
|
}
|
|
|
|
/*
|
|
* Buffers may be managed in a filesystem specific way.
|
|
* We must have no buffers or drop them.
|
|
*/
|
|
if (folio_test_private(src) &&
|
|
!filemap_release_folio(src, GFP_KERNEL))
|
|
return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
|
|
|
|
return migrate_folio(mapping, dst, src, mode);
|
|
}
|
|
|
|
/*
|
|
* Move a page to a newly allocated page
|
|
* The page is locked and all ptes have been successfully removed.
|
|
*
|
|
* The new page will have replaced the old page if this function
|
|
* is successful.
|
|
*
|
|
* Return value:
|
|
* < 0 - error code
|
|
* MIGRATEPAGE_SUCCESS - success
|
|
*/
|
|
static int move_to_new_folio(struct folio *dst, struct folio *src,
|
|
enum migrate_mode mode)
|
|
{
|
|
int rc = -EAGAIN;
|
|
bool is_lru = !__PageMovable(&src->page);
|
|
|
|
VM_BUG_ON_FOLIO(!folio_test_locked(src), src);
|
|
VM_BUG_ON_FOLIO(!folio_test_locked(dst), dst);
|
|
|
|
if (likely(is_lru)) {
|
|
struct address_space *mapping = folio_mapping(src);
|
|
|
|
if (!mapping)
|
|
rc = migrate_folio(mapping, dst, src, mode);
|
|
else if (mapping->a_ops->migrate_folio)
|
|
/*
|
|
* Most folios have a mapping and most filesystems
|
|
* provide a migrate_folio callback. Anonymous folios
|
|
* are part of swap space which also has its own
|
|
* migrate_folio callback. This is the most common path
|
|
* for page migration.
|
|
*/
|
|
rc = mapping->a_ops->migrate_folio(mapping, dst, src,
|
|
mode);
|
|
else
|
|
rc = fallback_migrate_folio(mapping, dst, src, mode);
|
|
} else {
|
|
const struct movable_operations *mops;
|
|
|
|
/*
|
|
* In case of non-lru page, it could be released after
|
|
* isolation step. In that case, we shouldn't try migration.
|
|
*/
|
|
VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
|
|
if (!folio_test_movable(src)) {
|
|
rc = MIGRATEPAGE_SUCCESS;
|
|
folio_clear_isolated(src);
|
|
goto out;
|
|
}
|
|
|
|
mops = page_movable_ops(&src->page);
|
|
rc = mops->migrate_page(&dst->page, &src->page, mode);
|
|
WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
|
|
!folio_test_isolated(src));
|
|
}
|
|
|
|
/*
|
|
* When successful, old pagecache src->mapping must be cleared before
|
|
* src is freed; but stats require that PageAnon be left as PageAnon.
|
|
*/
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
if (__PageMovable(&src->page)) {
|
|
VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
|
|
|
|
/*
|
|
* We clear PG_movable under page_lock so any compactor
|
|
* cannot try to migrate this page.
|
|
*/
|
|
folio_clear_isolated(src);
|
|
}
|
|
|
|
/*
|
|
* Anonymous and movable src->mapping will be cleared by
|
|
* free_pages_prepare so don't reset it here for keeping
|
|
* the type to work PageAnon, for example.
|
|
*/
|
|
if (!folio_mapping_flags(src))
|
|
src->mapping = NULL;
|
|
|
|
if (likely(!folio_is_zone_device(dst)))
|
|
flush_dcache_folio(dst);
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
static int __unmap_and_move(struct page *page, struct page *newpage,
|
|
int force, enum migrate_mode mode)
|
|
{
|
|
struct folio *folio = page_folio(page);
|
|
struct folio *dst = page_folio(newpage);
|
|
int rc = -EAGAIN;
|
|
bool page_was_mapped = false;
|
|
struct anon_vma *anon_vma = NULL;
|
|
bool is_lru = !__PageMovable(page);
|
|
|
|
if (!trylock_page(page)) {
|
|
if (!force || mode == MIGRATE_ASYNC)
|
|
goto out;
|
|
|
|
/*
|
|
* It's not safe for direct compaction to call lock_page.
|
|
* For example, during page readahead pages are added locked
|
|
* to the LRU. Later, when the IO completes the pages are
|
|
* marked uptodate and unlocked. However, the queueing
|
|
* could be merging multiple pages for one bio (e.g.
|
|
* mpage_readahead). If an allocation happens for the
|
|
* second or third page, the process can end up locking
|
|
* the same page twice and deadlocking. Rather than
|
|
* trying to be clever about what pages can be locked,
|
|
* avoid the use of lock_page for direct compaction
|
|
* altogether.
|
|
*/
|
|
if (current->flags & PF_MEMALLOC)
|
|
goto out;
|
|
|
|
lock_page(page);
|
|
}
|
|
|
|
if (PageWriteback(page)) {
|
|
/*
|
|
* Only in the case of a full synchronous migration is it
|
|
* necessary to wait for PageWriteback. In the async case,
|
|
* the retry loop is too short and in the sync-light case,
|
|
* the overhead of stalling is too much
|
|
*/
|
|
switch (mode) {
|
|
case MIGRATE_SYNC:
|
|
case MIGRATE_SYNC_NO_COPY:
|
|
break;
|
|
default:
|
|
rc = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
if (!force)
|
|
goto out_unlock;
|
|
wait_on_page_writeback(page);
|
|
}
|
|
|
|
/*
|
|
* By try_to_migrate(), page->mapcount goes down to 0 here. In this case,
|
|
* we cannot notice that anon_vma is freed while we migrates a page.
|
|
* This get_anon_vma() delays freeing anon_vma pointer until the end
|
|
* of migration. File cache pages are no problem because of page_lock()
|
|
* File Caches may use write_page() or lock_page() in migration, then,
|
|
* just care Anon page here.
|
|
*
|
|
* Only page_get_anon_vma() understands the subtleties of
|
|
* getting a hold on an anon_vma from outside one of its mms.
|
|
* But if we cannot get anon_vma, then we won't need it anyway,
|
|
* because that implies that the anon page is no longer mapped
|
|
* (and cannot be remapped so long as we hold the page lock).
|
|
*/
|
|
if (PageAnon(page) && !PageKsm(page))
|
|
anon_vma = page_get_anon_vma(page);
|
|
|
|
/*
|
|
* Block others from accessing the new page when we get around to
|
|
* establishing additional references. We are usually the only one
|
|
* holding a reference to newpage at this point. We used to have a BUG
|
|
* here if trylock_page(newpage) fails, but would like to allow for
|
|
* cases where there might be a race with the previous use of newpage.
|
|
* This is much like races on refcount of oldpage: just don't BUG().
|
|
*/
|
|
if (unlikely(!trylock_page(newpage)))
|
|
goto out_unlock;
|
|
|
|
if (unlikely(!is_lru)) {
|
|
rc = move_to_new_folio(dst, folio, mode);
|
|
goto out_unlock_both;
|
|
}
|
|
|
|
/*
|
|
* Corner case handling:
|
|
* 1. When a new swap-cache page is read into, it is added to the LRU
|
|
* and treated as swapcache but it has no rmap yet.
|
|
* Calling try_to_unmap() against a page->mapping==NULL page will
|
|
* trigger a BUG. So handle it here.
|
|
* 2. An orphaned page (see truncate_cleanup_page) might have
|
|
* fs-private metadata. The page can be picked up due to memory
|
|
* offlining. Everywhere else except page reclaim, the page is
|
|
* invisible to the vm, so the page can not be migrated. So try to
|
|
* free the metadata, so the page can be freed.
|
|
*/
|
|
if (!page->mapping) {
|
|
VM_BUG_ON_PAGE(PageAnon(page), page);
|
|
if (page_has_private(page)) {
|
|
try_to_free_buffers(folio);
|
|
goto out_unlock_both;
|
|
}
|
|
} else if (page_mapped(page)) {
|
|
/* Establish migration ptes */
|
|
VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma,
|
|
page);
|
|
try_to_migrate(folio, 0);
|
|
page_was_mapped = true;
|
|
}
|
|
|
|
if (!page_mapped(page))
|
|
rc = move_to_new_folio(dst, folio, mode);
|
|
|
|
/*
|
|
* When successful, push newpage to LRU immediately: so that if it
|
|
* turns out to be an mlocked page, remove_migration_ptes() will
|
|
* automatically build up the correct newpage->mlock_count for it.
|
|
*
|
|
* We would like to do something similar for the old page, when
|
|
* unsuccessful, and other cases when a page has been temporarily
|
|
* isolated from the unevictable LRU: but this case is the easiest.
|
|
*/
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
lru_cache_add(newpage);
|
|
if (page_was_mapped)
|
|
lru_add_drain();
|
|
}
|
|
|
|
if (page_was_mapped)
|
|
remove_migration_ptes(folio,
|
|
rc == MIGRATEPAGE_SUCCESS ? dst : folio, false);
|
|
|
|
out_unlock_both:
|
|
unlock_page(newpage);
|
|
out_unlock:
|
|
/* Drop an anon_vma reference if we took one */
|
|
if (anon_vma)
|
|
put_anon_vma(anon_vma);
|
|
unlock_page(page);
|
|
out:
|
|
/*
|
|
* If migration is successful, decrease refcount of the newpage,
|
|
* which will not free the page because new page owner increased
|
|
* refcounter.
|
|
*/
|
|
if (rc == MIGRATEPAGE_SUCCESS)
|
|
put_page(newpage);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* Obtain the lock on page, remove all ptes and migrate the page
|
|
* to the newly allocated page in newpage.
|
|
*/
|
|
static int unmap_and_move(new_page_t get_new_page,
|
|
free_page_t put_new_page,
|
|
unsigned long private, struct page *page,
|
|
int force, enum migrate_mode mode,
|
|
enum migrate_reason reason,
|
|
struct list_head *ret)
|
|
{
|
|
int rc = MIGRATEPAGE_SUCCESS;
|
|
struct page *newpage = NULL;
|
|
|
|
if (!thp_migration_supported() && PageTransHuge(page))
|
|
return -ENOSYS;
|
|
|
|
if (page_count(page) == 1) {
|
|
/* Page was freed from under us. So we are done. */
|
|
ClearPageActive(page);
|
|
ClearPageUnevictable(page);
|
|
/* free_pages_prepare() will clear PG_isolated. */
|
|
goto out;
|
|
}
|
|
|
|
newpage = get_new_page(page, private);
|
|
if (!newpage)
|
|
return -ENOMEM;
|
|
|
|
newpage->private = 0;
|
|
rc = __unmap_and_move(page, newpage, force, mode);
|
|
if (rc == MIGRATEPAGE_SUCCESS)
|
|
set_page_owner_migrate_reason(newpage, reason);
|
|
|
|
out:
|
|
if (rc != -EAGAIN) {
|
|
/*
|
|
* A page that has been migrated has all references
|
|
* removed and will be freed. A page that has not been
|
|
* migrated will have kept its references and be restored.
|
|
*/
|
|
list_del(&page->lru);
|
|
}
|
|
|
|
/*
|
|
* If migration is successful, releases reference grabbed during
|
|
* isolation. Otherwise, restore the page to right list unless
|
|
* we want to retry.
|
|
*/
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
/*
|
|
* Compaction can migrate also non-LRU pages which are
|
|
* not accounted to NR_ISOLATED_*. They can be recognized
|
|
* as __PageMovable
|
|
*/
|
|
if (likely(!__PageMovable(page)))
|
|
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
|
|
page_is_file_lru(page), -thp_nr_pages(page));
|
|
|
|
if (reason != MR_MEMORY_FAILURE)
|
|
/*
|
|
* We release the page in page_handle_poison.
|
|
*/
|
|
put_page(page);
|
|
} else {
|
|
if (rc != -EAGAIN)
|
|
list_add_tail(&page->lru, ret);
|
|
|
|
if (put_new_page)
|
|
put_new_page(newpage, private);
|
|
else
|
|
put_page(newpage);
|
|
}
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* Counterpart of unmap_and_move_page() for hugepage migration.
|
|
*
|
|
* This function doesn't wait the completion of hugepage I/O
|
|
* because there is no race between I/O and migration for hugepage.
|
|
* Note that currently hugepage I/O occurs only in direct I/O
|
|
* where no lock is held and PG_writeback is irrelevant,
|
|
* and writeback status of all subpages are counted in the reference
|
|
* count of the head page (i.e. if all subpages of a 2MB hugepage are
|
|
* under direct I/O, the reference of the head page is 512 and a bit more.)
|
|
* This means that when we try to migrate hugepage whose subpages are
|
|
* doing direct I/O, some references remain after try_to_unmap() and
|
|
* hugepage migration fails without data corruption.
|
|
*
|
|
* There is also no race when direct I/O is issued on the page under migration,
|
|
* because then pte is replaced with migration swap entry and direct I/O code
|
|
* will wait in the page fault for migration to complete.
|
|
*/
|
|
static int unmap_and_move_huge_page(new_page_t get_new_page,
|
|
free_page_t put_new_page, unsigned long private,
|
|
struct page *hpage, int force,
|
|
enum migrate_mode mode, int reason,
|
|
struct list_head *ret)
|
|
{
|
|
struct folio *dst, *src = page_folio(hpage);
|
|
int rc = -EAGAIN;
|
|
int page_was_mapped = 0;
|
|
struct page *new_hpage;
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct address_space *mapping = NULL;
|
|
|
|
/*
|
|
* Migratability of hugepages depends on architectures and their size.
|
|
* This check is necessary because some callers of hugepage migration
|
|
* like soft offline and memory hotremove don't walk through page
|
|
* tables or check whether the hugepage is pmd-based or not before
|
|
* kicking migration.
|
|
*/
|
|
if (!hugepage_migration_supported(page_hstate(hpage))) {
|
|
list_move_tail(&hpage->lru, ret);
|
|
return -ENOSYS;
|
|
}
|
|
|
|
if (page_count(hpage) == 1) {
|
|
/* page was freed from under us. So we are done. */
|
|
putback_active_hugepage(hpage);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
|
|
new_hpage = get_new_page(hpage, private);
|
|
if (!new_hpage)
|
|
return -ENOMEM;
|
|
dst = page_folio(new_hpage);
|
|
|
|
if (!trylock_page(hpage)) {
|
|
if (!force)
|
|
goto out;
|
|
switch (mode) {
|
|
case MIGRATE_SYNC:
|
|
case MIGRATE_SYNC_NO_COPY:
|
|
break;
|
|
default:
|
|
goto out;
|
|
}
|
|
lock_page(hpage);
|
|
}
|
|
|
|
/*
|
|
* Check for pages which are in the process of being freed. Without
|
|
* page_mapping() set, hugetlbfs specific move page routine will not
|
|
* be called and we could leak usage counts for subpools.
|
|
*/
|
|
if (hugetlb_page_subpool(hpage) && !page_mapping(hpage)) {
|
|
rc = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (PageAnon(hpage))
|
|
anon_vma = page_get_anon_vma(hpage);
|
|
|
|
if (unlikely(!trylock_page(new_hpage)))
|
|
goto put_anon;
|
|
|
|
if (page_mapped(hpage)) {
|
|
enum ttu_flags ttu = 0;
|
|
|
|
if (!PageAnon(hpage)) {
|
|
/*
|
|
* In shared mappings, try_to_unmap could potentially
|
|
* call huge_pmd_unshare. Because of this, take
|
|
* semaphore in write mode here and set TTU_RMAP_LOCKED
|
|
* to let lower levels know we have taken the lock.
|
|
*/
|
|
mapping = hugetlb_page_mapping_lock_write(hpage);
|
|
if (unlikely(!mapping))
|
|
goto unlock_put_anon;
|
|
|
|
ttu = TTU_RMAP_LOCKED;
|
|
}
|
|
|
|
try_to_migrate(src, ttu);
|
|
page_was_mapped = 1;
|
|
|
|
if (ttu & TTU_RMAP_LOCKED)
|
|
i_mmap_unlock_write(mapping);
|
|
}
|
|
|
|
if (!page_mapped(hpage))
|
|
rc = move_to_new_folio(dst, src, mode);
|
|
|
|
if (page_was_mapped)
|
|
remove_migration_ptes(src,
|
|
rc == MIGRATEPAGE_SUCCESS ? dst : src, false);
|
|
|
|
unlock_put_anon:
|
|
unlock_page(new_hpage);
|
|
|
|
put_anon:
|
|
if (anon_vma)
|
|
put_anon_vma(anon_vma);
|
|
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
move_hugetlb_state(hpage, new_hpage, reason);
|
|
put_new_page = NULL;
|
|
}
|
|
|
|
out_unlock:
|
|
unlock_page(hpage);
|
|
out:
|
|
if (rc == MIGRATEPAGE_SUCCESS)
|
|
putback_active_hugepage(hpage);
|
|
else if (rc != -EAGAIN)
|
|
list_move_tail(&hpage->lru, ret);
|
|
|
|
/*
|
|
* If migration was not successful and there's a freeing callback, use
|
|
* it. Otherwise, put_page() will drop the reference grabbed during
|
|
* isolation.
|
|
*/
|
|
if (put_new_page)
|
|
put_new_page(new_hpage, private);
|
|
else
|
|
putback_active_hugepage(new_hpage);
|
|
|
|
return rc;
|
|
}
|
|
|
|
static inline int try_split_thp(struct page *page, struct page **page2,
|
|
struct list_head *from)
|
|
{
|
|
int rc = 0;
|
|
|
|
lock_page(page);
|
|
rc = split_huge_page_to_list(page, from);
|
|
unlock_page(page);
|
|
if (!rc)
|
|
list_safe_reset_next(page, *page2, lru);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* migrate_pages - migrate the pages specified in a list, to the free pages
|
|
* supplied as the target for the page migration
|
|
*
|
|
* @from: The list of pages to be migrated.
|
|
* @get_new_page: The function used to allocate free pages to be used
|
|
* as the target of the page migration.
|
|
* @put_new_page: The function used to free target pages if migration
|
|
* fails, or NULL if no special handling is necessary.
|
|
* @private: Private data to be passed on to get_new_page()
|
|
* @mode: The migration mode that specifies the constraints for
|
|
* page migration, if any.
|
|
* @reason: The reason for page migration.
|
|
* @ret_succeeded: Set to the number of normal pages migrated successfully if
|
|
* the caller passes a non-NULL pointer.
|
|
*
|
|
* The function returns after 10 attempts or if no pages are movable any more
|
|
* because the list has become empty or no retryable pages exist any more.
|
|
* It is caller's responsibility to call putback_movable_pages() to return pages
|
|
* to the LRU or free list only if ret != 0.
|
|
*
|
|
* Returns the number of {normal page, THP, hugetlb} that were not migrated, or
|
|
* an error code. The number of THP splits will be considered as the number of
|
|
* non-migrated THP, no matter how many subpages of the THP are migrated successfully.
|
|
*/
|
|
int migrate_pages(struct list_head *from, new_page_t get_new_page,
|
|
free_page_t put_new_page, unsigned long private,
|
|
enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
|
|
{
|
|
int retry = 1;
|
|
int thp_retry = 1;
|
|
int nr_failed = 0;
|
|
int nr_failed_pages = 0;
|
|
int nr_succeeded = 0;
|
|
int nr_thp_succeeded = 0;
|
|
int nr_thp_failed = 0;
|
|
int nr_thp_split = 0;
|
|
int pass = 0;
|
|
bool is_thp = false;
|
|
struct page *page;
|
|
struct page *page2;
|
|
int rc, nr_subpages;
|
|
LIST_HEAD(ret_pages);
|
|
LIST_HEAD(thp_split_pages);
|
|
bool nosplit = (reason == MR_NUMA_MISPLACED);
|
|
bool no_subpage_counting = false;
|
|
|
|
trace_mm_migrate_pages_start(mode, reason);
|
|
|
|
thp_subpage_migration:
|
|
for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {
|
|
retry = 0;
|
|
thp_retry = 0;
|
|
|
|
list_for_each_entry_safe(page, page2, from, lru) {
|
|
retry:
|
|
/*
|
|
* THP statistics is based on the source huge page.
|
|
* Capture required information that might get lost
|
|
* during migration.
|
|
*/
|
|
is_thp = PageTransHuge(page) && !PageHuge(page);
|
|
nr_subpages = compound_nr(page);
|
|
cond_resched();
|
|
|
|
if (PageHuge(page))
|
|
rc = unmap_and_move_huge_page(get_new_page,
|
|
put_new_page, private, page,
|
|
pass > 2, mode, reason,
|
|
&ret_pages);
|
|
else
|
|
rc = unmap_and_move(get_new_page, put_new_page,
|
|
private, page, pass > 2, mode,
|
|
reason, &ret_pages);
|
|
/*
|
|
* The rules are:
|
|
* Success: non hugetlb page will be freed, hugetlb
|
|
* page will be put back
|
|
* -EAGAIN: stay on the from list
|
|
* -ENOMEM: stay on the from list
|
|
* Other errno: put on ret_pages list then splice to
|
|
* from list
|
|
*/
|
|
switch(rc) {
|
|
/*
|
|
* THP migration might be unsupported or the
|
|
* allocation could've failed so we should
|
|
* retry on the same page with the THP split
|
|
* to base pages.
|
|
*
|
|
* Head page is retried immediately and tail
|
|
* pages are added to the tail of the list so
|
|
* we encounter them after the rest of the list
|
|
* is processed.
|
|
*/
|
|
case -ENOSYS:
|
|
/* THP migration is unsupported */
|
|
if (is_thp) {
|
|
nr_thp_failed++;
|
|
if (!try_split_thp(page, &page2, &thp_split_pages)) {
|
|
nr_thp_split++;
|
|
goto retry;
|
|
}
|
|
/* Hugetlb migration is unsupported */
|
|
} else if (!no_subpage_counting) {
|
|
nr_failed++;
|
|
}
|
|
|
|
nr_failed_pages += nr_subpages;
|
|
break;
|
|
case -ENOMEM:
|
|
/*
|
|
* When memory is low, don't bother to try to migrate
|
|
* other pages, just exit.
|
|
* THP NUMA faulting doesn't split THP to retry.
|
|
*/
|
|
if (is_thp && !nosplit) {
|
|
nr_thp_failed++;
|
|
if (!try_split_thp(page, &page2, &thp_split_pages)) {
|
|
nr_thp_split++;
|
|
goto retry;
|
|
}
|
|
} else if (!no_subpage_counting) {
|
|
nr_failed++;
|
|
}
|
|
|
|
nr_failed_pages += nr_subpages;
|
|
/*
|
|
* There might be some subpages of fail-to-migrate THPs
|
|
* left in thp_split_pages list. Move them back to migration
|
|
* list so that they could be put back to the right list by
|
|
* the caller otherwise the page refcnt will be leaked.
|
|
*/
|
|
list_splice_init(&thp_split_pages, from);
|
|
nr_thp_failed += thp_retry;
|
|
goto out;
|
|
case -EAGAIN:
|
|
if (is_thp)
|
|
thp_retry++;
|
|
else
|
|
retry++;
|
|
break;
|
|
case MIGRATEPAGE_SUCCESS:
|
|
nr_succeeded += nr_subpages;
|
|
if (is_thp)
|
|
nr_thp_succeeded++;
|
|
break;
|
|
default:
|
|
/*
|
|
* Permanent failure (-EBUSY, etc.):
|
|
* unlike -EAGAIN case, the failed page is
|
|
* removed from migration page list and not
|
|
* retried in the next outer loop.
|
|
*/
|
|
if (is_thp)
|
|
nr_thp_failed++;
|
|
else if (!no_subpage_counting)
|
|
nr_failed++;
|
|
|
|
nr_failed_pages += nr_subpages;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
nr_failed += retry;
|
|
nr_thp_failed += thp_retry;
|
|
/*
|
|
* Try to migrate subpages of fail-to-migrate THPs, no nr_failed
|
|
* counting in this round, since all subpages of a THP is counted
|
|
* as 1 failure in the first round.
|
|
*/
|
|
if (!list_empty(&thp_split_pages)) {
|
|
/*
|
|
* Move non-migrated pages (after 10 retries) to ret_pages
|
|
* to avoid migrating them again.
|
|
*/
|
|
list_splice_init(from, &ret_pages);
|
|
list_splice_init(&thp_split_pages, from);
|
|
no_subpage_counting = true;
|
|
retry = 1;
|
|
goto thp_subpage_migration;
|
|
}
|
|
|
|
rc = nr_failed + nr_thp_failed;
|
|
out:
|
|
/*
|
|
* Put the permanent failure page back to migration list, they
|
|
* will be put back to the right list by the caller.
|
|
*/
|
|
list_splice(&ret_pages, from);
|
|
|
|
count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
|
|
count_vm_events(PGMIGRATE_FAIL, nr_failed_pages);
|
|
count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded);
|
|
count_vm_events(THP_MIGRATION_FAIL, nr_thp_failed);
|
|
count_vm_events(THP_MIGRATION_SPLIT, nr_thp_split);
|
|
trace_mm_migrate_pages(nr_succeeded, nr_failed_pages, nr_thp_succeeded,
|
|
nr_thp_failed, nr_thp_split, mode, reason);
|
|
|
|
if (ret_succeeded)
|
|
*ret_succeeded = nr_succeeded;
|
|
|
|
return rc;
|
|
}
|
|
|
|
struct page *alloc_migration_target(struct page *page, unsigned long private)
|
|
{
|
|
struct folio *folio = page_folio(page);
|
|
struct migration_target_control *mtc;
|
|
gfp_t gfp_mask;
|
|
unsigned int order = 0;
|
|
struct folio *new_folio = NULL;
|
|
int nid;
|
|
int zidx;
|
|
|
|
mtc = (struct migration_target_control *)private;
|
|
gfp_mask = mtc->gfp_mask;
|
|
nid = mtc->nid;
|
|
if (nid == NUMA_NO_NODE)
|
|
nid = folio_nid(folio);
|
|
|
|
if (folio_test_hugetlb(folio)) {
|
|
struct hstate *h = page_hstate(&folio->page);
|
|
|
|
gfp_mask = htlb_modify_alloc_mask(h, gfp_mask);
|
|
return alloc_huge_page_nodemask(h, nid, mtc->nmask, gfp_mask);
|
|
}
|
|
|
|
if (folio_test_large(folio)) {
|
|
/*
|
|
* clear __GFP_RECLAIM to make the migration callback
|
|
* consistent with regular THP allocations.
|
|
*/
|
|
gfp_mask &= ~__GFP_RECLAIM;
|
|
gfp_mask |= GFP_TRANSHUGE;
|
|
order = folio_order(folio);
|
|
}
|
|
zidx = zone_idx(folio_zone(folio));
|
|
if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
|
|
gfp_mask |= __GFP_HIGHMEM;
|
|
|
|
new_folio = __folio_alloc(gfp_mask, order, nid, mtc->nmask);
|
|
|
|
return &new_folio->page;
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
|
|
static int store_status(int __user *status, int start, int value, int nr)
|
|
{
|
|
while (nr-- > 0) {
|
|
if (put_user(value, status + start))
|
|
return -EFAULT;
|
|
start++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int do_move_pages_to_node(struct mm_struct *mm,
|
|
struct list_head *pagelist, int node)
|
|
{
|
|
int err;
|
|
struct migration_target_control mtc = {
|
|
.nid = node,
|
|
.gfp_mask = GFP_HIGHUSER_MOVABLE | __GFP_THISNODE,
|
|
};
|
|
|
|
err = migrate_pages(pagelist, alloc_migration_target, NULL,
|
|
(unsigned long)&mtc, MIGRATE_SYNC, MR_SYSCALL, NULL);
|
|
if (err)
|
|
putback_movable_pages(pagelist);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Resolves the given address to a struct page, isolates it from the LRU and
|
|
* puts it to the given pagelist.
|
|
* Returns:
|
|
* errno - if the page cannot be found/isolated
|
|
* 0 - when it doesn't have to be migrated because it is already on the
|
|
* target node
|
|
* 1 - when it has been queued
|
|
*/
|
|
static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
|
|
int node, struct list_head *pagelist, bool migrate_all)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct page *page;
|
|
int err;
|
|
|
|
mmap_read_lock(mm);
|
|
err = -EFAULT;
|
|
vma = vma_lookup(mm, addr);
|
|
if (!vma || !vma_migratable(vma))
|
|
goto out;
|
|
|
|
/* FOLL_DUMP to ignore special (like zero) pages */
|
|
page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
|
|
|
|
err = PTR_ERR(page);
|
|
if (IS_ERR(page))
|
|
goto out;
|
|
|
|
err = -ENOENT;
|
|
if (!page || is_zone_device_page(page))
|
|
goto out;
|
|
|
|
err = 0;
|
|
if (page_to_nid(page) == node)
|
|
goto out_putpage;
|
|
|
|
err = -EACCES;
|
|
if (page_mapcount(page) > 1 && !migrate_all)
|
|
goto out_putpage;
|
|
|
|
if (PageHuge(page)) {
|
|
if (PageHead(page)) {
|
|
err = isolate_hugetlb(page, pagelist);
|
|
if (!err)
|
|
err = 1;
|
|
}
|
|
} else {
|
|
struct page *head;
|
|
|
|
head = compound_head(page);
|
|
err = isolate_lru_page(head);
|
|
if (err)
|
|
goto out_putpage;
|
|
|
|
err = 1;
|
|
list_add_tail(&head->lru, pagelist);
|
|
mod_node_page_state(page_pgdat(head),
|
|
NR_ISOLATED_ANON + page_is_file_lru(head),
|
|
thp_nr_pages(head));
|
|
}
|
|
out_putpage:
|
|
/*
|
|
* Either remove the duplicate refcount from
|
|
* isolate_lru_page() or drop the page ref if it was
|
|
* not isolated.
|
|
*/
|
|
put_page(page);
|
|
out:
|
|
mmap_read_unlock(mm);
|
|
return err;
|
|
}
|
|
|
|
static int move_pages_and_store_status(struct mm_struct *mm, int node,
|
|
struct list_head *pagelist, int __user *status,
|
|
int start, int i, unsigned long nr_pages)
|
|
{
|
|
int err;
|
|
|
|
if (list_empty(pagelist))
|
|
return 0;
|
|
|
|
err = do_move_pages_to_node(mm, pagelist, node);
|
|
if (err) {
|
|
/*
|
|
* Positive err means the number of failed
|
|
* pages to migrate. Since we are going to
|
|
* abort and return the number of non-migrated
|
|
* pages, so need to include the rest of the
|
|
* nr_pages that have not been attempted as
|
|
* well.
|
|
*/
|
|
if (err > 0)
|
|
err += nr_pages - i - 1;
|
|
return err;
|
|
}
|
|
return store_status(status, start, node, i - start);
|
|
}
|
|
|
|
/*
|
|
* Migrate an array of page address onto an array of nodes and fill
|
|
* the corresponding array of status.
|
|
*/
|
|
static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
|
|
unsigned long nr_pages,
|
|
const void __user * __user *pages,
|
|
const int __user *nodes,
|
|
int __user *status, int flags)
|
|
{
|
|
int current_node = NUMA_NO_NODE;
|
|
LIST_HEAD(pagelist);
|
|
int start, i;
|
|
int err = 0, err1;
|
|
|
|
lru_cache_disable();
|
|
|
|
for (i = start = 0; i < nr_pages; i++) {
|
|
const void __user *p;
|
|
unsigned long addr;
|
|
int node;
|
|
|
|
err = -EFAULT;
|
|
if (get_user(p, pages + i))
|
|
goto out_flush;
|
|
if (get_user(node, nodes + i))
|
|
goto out_flush;
|
|
addr = (unsigned long)untagged_addr(p);
|
|
|
|
err = -ENODEV;
|
|
if (node < 0 || node >= MAX_NUMNODES)
|
|
goto out_flush;
|
|
if (!node_state(node, N_MEMORY))
|
|
goto out_flush;
|
|
|
|
err = -EACCES;
|
|
if (!node_isset(node, task_nodes))
|
|
goto out_flush;
|
|
|
|
if (current_node == NUMA_NO_NODE) {
|
|
current_node = node;
|
|
start = i;
|
|
} else if (node != current_node) {
|
|
err = move_pages_and_store_status(mm, current_node,
|
|
&pagelist, status, start, i, nr_pages);
|
|
if (err)
|
|
goto out;
|
|
start = i;
|
|
current_node = node;
|
|
}
|
|
|
|
/*
|
|
* Errors in the page lookup or isolation are not fatal and we simply
|
|
* report them via status
|
|
*/
|
|
err = add_page_for_migration(mm, addr, current_node,
|
|
&pagelist, flags & MPOL_MF_MOVE_ALL);
|
|
|
|
if (err > 0) {
|
|
/* The page is successfully queued for migration */
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* The move_pages() man page does not have an -EEXIST choice, so
|
|
* use -EFAULT instead.
|
|
*/
|
|
if (err == -EEXIST)
|
|
err = -EFAULT;
|
|
|
|
/*
|
|
* If the page is already on the target node (!err), store the
|
|
* node, otherwise, store the err.
|
|
*/
|
|
err = store_status(status, i, err ? : current_node, 1);
|
|
if (err)
|
|
goto out_flush;
|
|
|
|
err = move_pages_and_store_status(mm, current_node, &pagelist,
|
|
status, start, i, nr_pages);
|
|
if (err)
|
|
goto out;
|
|
current_node = NUMA_NO_NODE;
|
|
}
|
|
out_flush:
|
|
/* Make sure we do not overwrite the existing error */
|
|
err1 = move_pages_and_store_status(mm, current_node, &pagelist,
|
|
status, start, i, nr_pages);
|
|
if (err >= 0)
|
|
err = err1;
|
|
out:
|
|
lru_cache_enable();
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Determine the nodes of an array of pages and store it in an array of status.
|
|
*/
|
|
static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
|
|
const void __user **pages, int *status)
|
|
{
|
|
unsigned long i;
|
|
|
|
mmap_read_lock(mm);
|
|
|
|
for (i = 0; i < nr_pages; i++) {
|
|
unsigned long addr = (unsigned long)(*pages);
|
|
unsigned int foll_flags = FOLL_DUMP;
|
|
struct vm_area_struct *vma;
|
|
struct page *page;
|
|
int err = -EFAULT;
|
|
|
|
vma = vma_lookup(mm, addr);
|
|
if (!vma)
|
|
goto set_status;
|
|
|
|
/* Not all huge page follow APIs support 'FOLL_GET' */
|
|
if (!is_vm_hugetlb_page(vma))
|
|
foll_flags |= FOLL_GET;
|
|
|
|
/* FOLL_DUMP to ignore special (like zero) pages */
|
|
page = follow_page(vma, addr, foll_flags);
|
|
|
|
err = PTR_ERR(page);
|
|
if (IS_ERR(page))
|
|
goto set_status;
|
|
|
|
if (page && !is_zone_device_page(page)) {
|
|
err = page_to_nid(page);
|
|
if (foll_flags & FOLL_GET)
|
|
put_page(page);
|
|
} else {
|
|
err = -ENOENT;
|
|
}
|
|
set_status:
|
|
*status = err;
|
|
|
|
pages++;
|
|
status++;
|
|
}
|
|
|
|
mmap_read_unlock(mm);
|
|
}
|
|
|
|
static int get_compat_pages_array(const void __user *chunk_pages[],
|
|
const void __user * __user *pages,
|
|
unsigned long chunk_nr)
|
|
{
|
|
compat_uptr_t __user *pages32 = (compat_uptr_t __user *)pages;
|
|
compat_uptr_t p;
|
|
int i;
|
|
|
|
for (i = 0; i < chunk_nr; i++) {
|
|
if (get_user(p, pages32 + i))
|
|
return -EFAULT;
|
|
chunk_pages[i] = compat_ptr(p);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Determine the nodes of a user array of pages and store it in
|
|
* a user array of status.
|
|
*/
|
|
static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
|
|
const void __user * __user *pages,
|
|
int __user *status)
|
|
{
|
|
#define DO_PAGES_STAT_CHUNK_NR 16UL
|
|
const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
|
|
int chunk_status[DO_PAGES_STAT_CHUNK_NR];
|
|
|
|
while (nr_pages) {
|
|
unsigned long chunk_nr = min(nr_pages, DO_PAGES_STAT_CHUNK_NR);
|
|
|
|
if (in_compat_syscall()) {
|
|
if (get_compat_pages_array(chunk_pages, pages,
|
|
chunk_nr))
|
|
break;
|
|
} else {
|
|
if (copy_from_user(chunk_pages, pages,
|
|
chunk_nr * sizeof(*chunk_pages)))
|
|
break;
|
|
}
|
|
|
|
do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
|
|
|
|
if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
|
|
break;
|
|
|
|
pages += chunk_nr;
|
|
status += chunk_nr;
|
|
nr_pages -= chunk_nr;
|
|
}
|
|
return nr_pages ? -EFAULT : 0;
|
|
}
|
|
|
|
static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes)
|
|
{
|
|
struct task_struct *task;
|
|
struct mm_struct *mm;
|
|
|
|
/*
|
|
* There is no need to check if current process has the right to modify
|
|
* the specified process when they are same.
|
|
*/
|
|
if (!pid) {
|
|
mmget(current->mm);
|
|
*mem_nodes = cpuset_mems_allowed(current);
|
|
return current->mm;
|
|
}
|
|
|
|
/* Find the mm_struct */
|
|
rcu_read_lock();
|
|
task = find_task_by_vpid(pid);
|
|
if (!task) {
|
|
rcu_read_unlock();
|
|
return ERR_PTR(-ESRCH);
|
|
}
|
|
get_task_struct(task);
|
|
|
|
/*
|
|
* Check if this process has the right to modify the specified
|
|
* process. Use the regular "ptrace_may_access()" checks.
|
|
*/
|
|
if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
|
|
rcu_read_unlock();
|
|
mm = ERR_PTR(-EPERM);
|
|
goto out;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
mm = ERR_PTR(security_task_movememory(task));
|
|
if (IS_ERR(mm))
|
|
goto out;
|
|
*mem_nodes = cpuset_mems_allowed(task);
|
|
mm = get_task_mm(task);
|
|
out:
|
|
put_task_struct(task);
|
|
if (!mm)
|
|
mm = ERR_PTR(-EINVAL);
|
|
return mm;
|
|
}
|
|
|
|
/*
|
|
* Move a list of pages in the address space of the currently executing
|
|
* process.
|
|
*/
|
|
static int kernel_move_pages(pid_t pid, unsigned long nr_pages,
|
|
const void __user * __user *pages,
|
|
const int __user *nodes,
|
|
int __user *status, int flags)
|
|
{
|
|
struct mm_struct *mm;
|
|
int err;
|
|
nodemask_t task_nodes;
|
|
|
|
/* Check flags */
|
|
if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
|
|
return -EINVAL;
|
|
|
|
if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
|
|
return -EPERM;
|
|
|
|
mm = find_mm_struct(pid, &task_nodes);
|
|
if (IS_ERR(mm))
|
|
return PTR_ERR(mm);
|
|
|
|
if (nodes)
|
|
err = do_pages_move(mm, task_nodes, nr_pages, pages,
|
|
nodes, status, flags);
|
|
else
|
|
err = do_pages_stat(mm, nr_pages, pages, status);
|
|
|
|
mmput(mm);
|
|
return err;
|
|
}
|
|
|
|
SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
|
|
const void __user * __user *, pages,
|
|
const int __user *, nodes,
|
|
int __user *, status, int, flags)
|
|
{
|
|
return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags);
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
/*
|
|
* Returns true if this is a safe migration target node for misplaced NUMA
|
|
* pages. Currently it only checks the watermarks which is crude.
|
|
*/
|
|
static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
|
|
unsigned long nr_migrate_pages)
|
|
{
|
|
int z;
|
|
|
|
for (z = pgdat->nr_zones - 1; z >= 0; z--) {
|
|
struct zone *zone = pgdat->node_zones + z;
|
|
|
|
if (!managed_zone(zone))
|
|
continue;
|
|
|
|
/* Avoid waking kswapd by allocating pages_to_migrate pages. */
|
|
if (!zone_watermark_ok(zone, 0,
|
|
high_wmark_pages(zone) +
|
|
nr_migrate_pages,
|
|
ZONE_MOVABLE, 0))
|
|
continue;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static struct page *alloc_misplaced_dst_page(struct page *page,
|
|
unsigned long data)
|
|
{
|
|
int nid = (int) data;
|
|
int order = compound_order(page);
|
|
gfp_t gfp = __GFP_THISNODE;
|
|
struct folio *new;
|
|
|
|
if (order > 0)
|
|
gfp |= GFP_TRANSHUGE_LIGHT;
|
|
else {
|
|
gfp |= GFP_HIGHUSER_MOVABLE | __GFP_NOMEMALLOC | __GFP_NORETRY |
|
|
__GFP_NOWARN;
|
|
gfp &= ~__GFP_RECLAIM;
|
|
}
|
|
new = __folio_alloc_node(gfp, order, nid);
|
|
|
|
return &new->page;
|
|
}
|
|
|
|
static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
|
|
{
|
|
int nr_pages = thp_nr_pages(page);
|
|
int order = compound_order(page);
|
|
|
|
VM_BUG_ON_PAGE(order && !PageTransHuge(page), page);
|
|
|
|
/* Do not migrate THP mapped by multiple processes */
|
|
if (PageTransHuge(page) && total_mapcount(page) > 1)
|
|
return 0;
|
|
|
|
/* Avoid migrating to a node that is nearly full */
|
|
if (!migrate_balanced_pgdat(pgdat, nr_pages)) {
|
|
int z;
|
|
|
|
if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING))
|
|
return 0;
|
|
for (z = pgdat->nr_zones - 1; z >= 0; z--) {
|
|
if (managed_zone(pgdat->node_zones + z))
|
|
break;
|
|
}
|
|
wakeup_kswapd(pgdat->node_zones + z, 0, order, ZONE_MOVABLE);
|
|
return 0;
|
|
}
|
|
|
|
if (isolate_lru_page(page))
|
|
return 0;
|
|
|
|
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_is_file_lru(page),
|
|
nr_pages);
|
|
|
|
/*
|
|
* Isolating the page has taken another reference, so the
|
|
* caller's reference can be safely dropped without the page
|
|
* disappearing underneath us during migration.
|
|
*/
|
|
put_page(page);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Attempt to migrate a misplaced page to the specified destination
|
|
* node. Caller is expected to have an elevated reference count on
|
|
* the page that will be dropped by this function before returning.
|
|
*/
|
|
int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
|
|
int node)
|
|
{
|
|
pg_data_t *pgdat = NODE_DATA(node);
|
|
int isolated;
|
|
int nr_remaining;
|
|
unsigned int nr_succeeded;
|
|
LIST_HEAD(migratepages);
|
|
int nr_pages = thp_nr_pages(page);
|
|
|
|
/*
|
|
* Don't migrate file pages that are mapped in multiple processes
|
|
* with execute permissions as they are probably shared libraries.
|
|
*/
|
|
if (page_mapcount(page) != 1 && page_is_file_lru(page) &&
|
|
(vma->vm_flags & VM_EXEC))
|
|
goto out;
|
|
|
|
/*
|
|
* Also do not migrate dirty pages as not all filesystems can move
|
|
* dirty pages in MIGRATE_ASYNC mode which is a waste of cycles.
|
|
*/
|
|
if (page_is_file_lru(page) && PageDirty(page))
|
|
goto out;
|
|
|
|
isolated = numamigrate_isolate_page(pgdat, page);
|
|
if (!isolated)
|
|
goto out;
|
|
|
|
list_add(&page->lru, &migratepages);
|
|
nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page,
|
|
NULL, node, MIGRATE_ASYNC,
|
|
MR_NUMA_MISPLACED, &nr_succeeded);
|
|
if (nr_remaining) {
|
|
if (!list_empty(&migratepages)) {
|
|
list_del(&page->lru);
|
|
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
|
|
page_is_file_lru(page), -nr_pages);
|
|
putback_lru_page(page);
|
|
}
|
|
isolated = 0;
|
|
}
|
|
if (nr_succeeded) {
|
|
count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
|
|
if (!node_is_toptier(page_to_nid(page)) && node_is_toptier(node))
|
|
mod_node_page_state(pgdat, PGPROMOTE_SUCCESS,
|
|
nr_succeeded);
|
|
}
|
|
BUG_ON(!list_empty(&migratepages));
|
|
return isolated;
|
|
|
|
out:
|
|
put_page(page);
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
|
|
/*
|
|
* node_demotion[] example:
|
|
*
|
|
* Consider a system with two sockets. Each socket has
|
|
* three classes of memory attached: fast, medium and slow.
|
|
* Each memory class is placed in its own NUMA node. The
|
|
* CPUs are placed in the node with the "fast" memory. The
|
|
* 6 NUMA nodes (0-5) might be split among the sockets like
|
|
* this:
|
|
*
|
|
* Socket A: 0, 1, 2
|
|
* Socket B: 3, 4, 5
|
|
*
|
|
* When Node 0 fills up, its memory should be migrated to
|
|
* Node 1. When Node 1 fills up, it should be migrated to
|
|
* Node 2. The migration path start on the nodes with the
|
|
* processors (since allocations default to this node) and
|
|
* fast memory, progress through medium and end with the
|
|
* slow memory:
|
|
*
|
|
* 0 -> 1 -> 2 -> stop
|
|
* 3 -> 4 -> 5 -> stop
|
|
*
|
|
* This is represented in the node_demotion[] like this:
|
|
*
|
|
* { nr=1, nodes[0]=1 }, // Node 0 migrates to 1
|
|
* { nr=1, nodes[0]=2 }, // Node 1 migrates to 2
|
|
* { nr=0, nodes[0]=-1 }, // Node 2 does not migrate
|
|
* { nr=1, nodes[0]=4 }, // Node 3 migrates to 4
|
|
* { nr=1, nodes[0]=5 }, // Node 4 migrates to 5
|
|
* { nr=0, nodes[0]=-1 }, // Node 5 does not migrate
|
|
*
|
|
* Moreover some systems may have multiple slow memory nodes.
|
|
* Suppose a system has one socket with 3 memory nodes, node 0
|
|
* is fast memory type, and node 1/2 both are slow memory
|
|
* type, and the distance between fast memory node and slow
|
|
* memory node is same. So the migration path should be:
|
|
*
|
|
* 0 -> 1/2 -> stop
|
|
*
|
|
* This is represented in the node_demotion[] like this:
|
|
* { nr=2, {nodes[0]=1, nodes[1]=2} }, // Node 0 migrates to node 1 and node 2
|
|
* { nr=0, nodes[0]=-1, }, // Node 1 dose not migrate
|
|
* { nr=0, nodes[0]=-1, }, // Node 2 does not migrate
|
|
*/
|
|
|
|
/*
|
|
* Writes to this array occur without locking. Cycles are
|
|
* not allowed: Node X demotes to Y which demotes to X...
|
|
*
|
|
* If multiple reads are performed, a single rcu_read_lock()
|
|
* must be held over all reads to ensure that no cycles are
|
|
* observed.
|
|
*/
|
|
#define DEFAULT_DEMOTION_TARGET_NODES 15
|
|
|
|
#if MAX_NUMNODES < DEFAULT_DEMOTION_TARGET_NODES
|
|
#define DEMOTION_TARGET_NODES (MAX_NUMNODES - 1)
|
|
#else
|
|
#define DEMOTION_TARGET_NODES DEFAULT_DEMOTION_TARGET_NODES
|
|
#endif
|
|
|
|
struct demotion_nodes {
|
|
unsigned short nr;
|
|
short nodes[DEMOTION_TARGET_NODES];
|
|
};
|
|
|
|
static struct demotion_nodes *node_demotion __read_mostly;
|
|
|
|
/**
|
|
* next_demotion_node() - Get the next node in the demotion path
|
|
* @node: The starting node to lookup the next node
|
|
*
|
|
* Return: node id for next memory node in the demotion path hierarchy
|
|
* from @node; NUMA_NO_NODE if @node is terminal. This does not keep
|
|
* @node online or guarantee that it *continues* to be the next demotion
|
|
* target.
|
|
*/
|
|
int next_demotion_node(int node)
|
|
{
|
|
struct demotion_nodes *nd;
|
|
unsigned short target_nr, index;
|
|
int target;
|
|
|
|
if (!node_demotion)
|
|
return NUMA_NO_NODE;
|
|
|
|
nd = &node_demotion[node];
|
|
|
|
/*
|
|
* node_demotion[] is updated without excluding this
|
|
* function from running. RCU doesn't provide any
|
|
* compiler barriers, so the READ_ONCE() is required
|
|
* to avoid compiler reordering or read merging.
|
|
*
|
|
* Make sure to use RCU over entire code blocks if
|
|
* node_demotion[] reads need to be consistent.
|
|
*/
|
|
rcu_read_lock();
|
|
target_nr = READ_ONCE(nd->nr);
|
|
|
|
switch (target_nr) {
|
|
case 0:
|
|
target = NUMA_NO_NODE;
|
|
goto out;
|
|
case 1:
|
|
index = 0;
|
|
break;
|
|
default:
|
|
/*
|
|
* If there are multiple target nodes, just select one
|
|
* target node randomly.
|
|
*
|
|
* In addition, we can also use round-robin to select
|
|
* target node, but we should introduce another variable
|
|
* for node_demotion[] to record last selected target node,
|
|
* that may cause cache ping-pong due to the changing of
|
|
* last target node. Or introducing per-cpu data to avoid
|
|
* caching issue, which seems more complicated. So selecting
|
|
* target node randomly seems better until now.
|
|
*/
|
|
index = get_random_int() % target_nr;
|
|
break;
|
|
}
|
|
|
|
target = READ_ONCE(nd->nodes[index]);
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
return target;
|
|
}
|
|
|
|
/* Disable reclaim-based migration. */
|
|
static void __disable_all_migrate_targets(void)
|
|
{
|
|
int node, i;
|
|
|
|
if (!node_demotion)
|
|
return;
|
|
|
|
for_each_online_node(node) {
|
|
node_demotion[node].nr = 0;
|
|
for (i = 0; i < DEMOTION_TARGET_NODES; i++)
|
|
node_demotion[node].nodes[i] = NUMA_NO_NODE;
|
|
}
|
|
}
|
|
|
|
static void disable_all_migrate_targets(void)
|
|
{
|
|
__disable_all_migrate_targets();
|
|
|
|
/*
|
|
* Ensure that the "disable" is visible across the system.
|
|
* Readers will see either a combination of before+disable
|
|
* state or disable+after. They will never see before and
|
|
* after state together.
|
|
*
|
|
* The before+after state together might have cycles and
|
|
* could cause readers to do things like loop until this
|
|
* function finishes. This ensures they can only see a
|
|
* single "bad" read and would, for instance, only loop
|
|
* once.
|
|
*/
|
|
synchronize_rcu();
|
|
}
|
|
|
|
/*
|
|
* Find an automatic demotion target for 'node'.
|
|
* Failing here is OK. It might just indicate
|
|
* being at the end of a chain.
|
|
*/
|
|
static int establish_migrate_target(int node, nodemask_t *used,
|
|
int best_distance)
|
|
{
|
|
int migration_target, index, val;
|
|
struct demotion_nodes *nd;
|
|
|
|
if (!node_demotion)
|
|
return NUMA_NO_NODE;
|
|
|
|
nd = &node_demotion[node];
|
|
|
|
migration_target = find_next_best_node(node, used);
|
|
if (migration_target == NUMA_NO_NODE)
|
|
return NUMA_NO_NODE;
|
|
|
|
/*
|
|
* If the node has been set a migration target node before,
|
|
* which means it's the best distance between them. Still
|
|
* check if this node can be demoted to other target nodes
|
|
* if they have a same best distance.
|
|
*/
|
|
if (best_distance != -1) {
|
|
val = node_distance(node, migration_target);
|
|
if (val > best_distance)
|
|
goto out_clear;
|
|
}
|
|
|
|
index = nd->nr;
|
|
if (WARN_ONCE(index >= DEMOTION_TARGET_NODES,
|
|
"Exceeds maximum demotion target nodes\n"))
|
|
goto out_clear;
|
|
|
|
nd->nodes[index] = migration_target;
|
|
nd->nr++;
|
|
|
|
return migration_target;
|
|
out_clear:
|
|
node_clear(migration_target, *used);
|
|
return NUMA_NO_NODE;
|
|
}
|
|
|
|
/*
|
|
* When memory fills up on a node, memory contents can be
|
|
* automatically migrated to another node instead of
|
|
* discarded at reclaim.
|
|
*
|
|
* Establish a "migration path" which will start at nodes
|
|
* with CPUs and will follow the priorities used to build the
|
|
* page allocator zonelists.
|
|
*
|
|
* The difference here is that cycles must be avoided. If
|
|
* node0 migrates to node1, then neither node1, nor anything
|
|
* node1 migrates to can migrate to node0. Also one node can
|
|
* be migrated to multiple nodes if the target nodes all have
|
|
* a same best-distance against the source node.
|
|
*
|
|
* This function can run simultaneously with readers of
|
|
* node_demotion[]. However, it can not run simultaneously
|
|
* with itself. Exclusion is provided by memory hotplug events
|
|
* being single-threaded.
|
|
*/
|
|
static void __set_migration_target_nodes(void)
|
|
{
|
|
nodemask_t next_pass;
|
|
nodemask_t this_pass;
|
|
nodemask_t used_targets = NODE_MASK_NONE;
|
|
int node, best_distance;
|
|
|
|
/*
|
|
* Avoid any oddities like cycles that could occur
|
|
* from changes in the topology. This will leave
|
|
* a momentary gap when migration is disabled.
|
|
*/
|
|
disable_all_migrate_targets();
|
|
|
|
/*
|
|
* Allocations go close to CPUs, first. Assume that
|
|
* the migration path starts at the nodes with CPUs.
|
|
*/
|
|
next_pass = node_states[N_CPU];
|
|
again:
|
|
this_pass = next_pass;
|
|
next_pass = NODE_MASK_NONE;
|
|
/*
|
|
* To avoid cycles in the migration "graph", ensure
|
|
* that migration sources are not future targets by
|
|
* setting them in 'used_targets'. Do this only
|
|
* once per pass so that multiple source nodes can
|
|
* share a target node.
|
|
*
|
|
* 'used_targets' will become unavailable in future
|
|
* passes. This limits some opportunities for
|
|
* multiple source nodes to share a destination.
|
|
*/
|
|
nodes_or(used_targets, used_targets, this_pass);
|
|
|
|
for_each_node_mask(node, this_pass) {
|
|
best_distance = -1;
|
|
|
|
/*
|
|
* Try to set up the migration path for the node, and the target
|
|
* migration nodes can be multiple, so doing a loop to find all
|
|
* the target nodes if they all have a best node distance.
|
|
*/
|
|
do {
|
|
int target_node =
|
|
establish_migrate_target(node, &used_targets,
|
|
best_distance);
|
|
|
|
if (target_node == NUMA_NO_NODE)
|
|
break;
|
|
|
|
if (best_distance == -1)
|
|
best_distance = node_distance(node, target_node);
|
|
|
|
/*
|
|
* Visit targets from this pass in the next pass.
|
|
* Eventually, every node will have been part of
|
|
* a pass, and will become set in 'used_targets'.
|
|
*/
|
|
node_set(target_node, next_pass);
|
|
} while (1);
|
|
}
|
|
/*
|
|
* 'next_pass' contains nodes which became migration
|
|
* targets in this pass. Make additional passes until
|
|
* no more migrations targets are available.
|
|
*/
|
|
if (!nodes_empty(next_pass))
|
|
goto again;
|
|
}
|
|
|
|
/*
|
|
* For callers that do not hold get_online_mems() already.
|
|
*/
|
|
void set_migration_target_nodes(void)
|
|
{
|
|
get_online_mems();
|
|
__set_migration_target_nodes();
|
|
put_online_mems();
|
|
}
|
|
|
|
/*
|
|
* This leaves migrate-on-reclaim transiently disabled between
|
|
* the MEM_GOING_OFFLINE and MEM_OFFLINE events. This runs
|
|
* whether reclaim-based migration is enabled or not, which
|
|
* ensures that the user can turn reclaim-based migration at
|
|
* any time without needing to recalculate migration targets.
|
|
*
|
|
* These callbacks already hold get_online_mems(). That is why
|
|
* __set_migration_target_nodes() can be used as opposed to
|
|
* set_migration_target_nodes().
|
|
*/
|
|
#ifdef CONFIG_MEMORY_HOTPLUG
|
|
static int __meminit migrate_on_reclaim_callback(struct notifier_block *self,
|
|
unsigned long action, void *_arg)
|
|
{
|
|
struct memory_notify *arg = _arg;
|
|
|
|
/*
|
|
* Only update the node migration order when a node is
|
|
* changing status, like online->offline. This avoids
|
|
* the overhead of synchronize_rcu() in most cases.
|
|
*/
|
|
if (arg->status_change_nid < 0)
|
|
return notifier_from_errno(0);
|
|
|
|
switch (action) {
|
|
case MEM_GOING_OFFLINE:
|
|
/*
|
|
* Make sure there are not transient states where
|
|
* an offline node is a migration target. This
|
|
* will leave migration disabled until the offline
|
|
* completes and the MEM_OFFLINE case below runs.
|
|
*/
|
|
disable_all_migrate_targets();
|
|
break;
|
|
case MEM_OFFLINE:
|
|
case MEM_ONLINE:
|
|
/*
|
|
* Recalculate the target nodes once the node
|
|
* reaches its final state (online or offline).
|
|
*/
|
|
__set_migration_target_nodes();
|
|
break;
|
|
case MEM_CANCEL_OFFLINE:
|
|
/*
|
|
* MEM_GOING_OFFLINE disabled all the migration
|
|
* targets. Reenable them.
|
|
*/
|
|
__set_migration_target_nodes();
|
|
break;
|
|
case MEM_GOING_ONLINE:
|
|
case MEM_CANCEL_ONLINE:
|
|
break;
|
|
}
|
|
|
|
return notifier_from_errno(0);
|
|
}
|
|
#endif
|
|
|
|
void __init migrate_on_reclaim_init(void)
|
|
{
|
|
node_demotion = kcalloc(nr_node_ids,
|
|
sizeof(struct demotion_nodes),
|
|
GFP_KERNEL);
|
|
WARN_ON(!node_demotion);
|
|
#ifdef CONFIG_MEMORY_HOTPLUG
|
|
hotplug_memory_notifier(migrate_on_reclaim_callback, 100);
|
|
#endif
|
|
/*
|
|
* At this point, all numa nodes with memory/CPus have their state
|
|
* properly set, so we can build the demotion order now.
|
|
* Let us hold the cpu_hotplug lock just, as we could possibily have
|
|
* CPU hotplug events during boot.
|
|
*/
|
|
cpus_read_lock();
|
|
set_migration_target_nodes();
|
|
cpus_read_unlock();
|
|
}
|
|
|
|
bool numa_demotion_enabled = false;
|
|
|
|
#ifdef CONFIG_SYSFS
|
|
static ssize_t numa_demotion_enabled_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr, char *buf)
|
|
{
|
|
return sysfs_emit(buf, "%s\n",
|
|
numa_demotion_enabled ? "true" : "false");
|
|
}
|
|
|
|
static ssize_t numa_demotion_enabled_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
ssize_t ret;
|
|
|
|
ret = kstrtobool(buf, &numa_demotion_enabled);
|
|
if (ret)
|
|
return ret;
|
|
|
|
return count;
|
|
}
|
|
|
|
static struct kobj_attribute numa_demotion_enabled_attr =
|
|
__ATTR(demotion_enabled, 0644, numa_demotion_enabled_show,
|
|
numa_demotion_enabled_store);
|
|
|
|
static struct attribute *numa_attrs[] = {
|
|
&numa_demotion_enabled_attr.attr,
|
|
NULL,
|
|
};
|
|
|
|
static const struct attribute_group numa_attr_group = {
|
|
.attrs = numa_attrs,
|
|
};
|
|
|
|
static int __init numa_init_sysfs(void)
|
|
{
|
|
int err;
|
|
struct kobject *numa_kobj;
|
|
|
|
numa_kobj = kobject_create_and_add("numa", mm_kobj);
|
|
if (!numa_kobj) {
|
|
pr_err("failed to create numa kobject\n");
|
|
return -ENOMEM;
|
|
}
|
|
err = sysfs_create_group(numa_kobj, &numa_attr_group);
|
|
if (err) {
|
|
pr_err("failed to register numa group\n");
|
|
goto delete_obj;
|
|
}
|
|
return 0;
|
|
|
|
delete_obj:
|
|
kobject_put(numa_kobj);
|
|
return err;
|
|
}
|
|
subsys_initcall(numa_init_sysfs);
|
|
#endif /* CONFIG_SYSFS */
|
|
#endif /* CONFIG_NUMA */
|