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Not all huge page APIs support FOLL_GET option, so move_pages() syscall
will fail to get the page node information for some huge pages.
Like x86 on linux 5.19 with 1GB huge page API follow_huge_pud(), it will
return NULL page for FOLL_GET when calling move_pages() syscall with the
NULL 'nodes' parameter, the 'status' parameter has '-2' error in array.
Note: follow_huge_pud() now supports FOLL_GET in linux 6.0.
Link: https://lore.kernel.org/all/20220714042420.1847125-3-naoya.horiguchi@linux.dev
But these huge page APIs don't support FOLL_GET:
1. follow_huge_pud() in arch/s390/mm/hugetlbpage.c
2. follow_huge_addr() in arch/ia64/mm/hugetlbpage.c
It will cause WARN_ON_ONCE for FOLL_GET.
3. follow_huge_pgd() in mm/hugetlb.c
This is an temporary solution to mitigate the side effect of the race
condition fix by calling follow_page() with FOLL_GET set for huge pages.
After supporting follow huge page by FOLL_GET is done, this fix can be
reverted safely.
Link: https://lkml.kernel.org/r/20220823135841.934465-2-haiyue.wang@intel.com
Link: https://lkml.kernel.org/r/20220812084921.409142-1-haiyue.wang@intel.com
Fixes: 4cd614841c06 ("mm: migration: fix possible do_pages_stat_array racing with memory offline")
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After patch "mm/workingset: prepare the workingset detection
infrastructure for anon LRU", we can handle the refaults of anonymous
pages too. So the annotations of refaults should cover both of anonymous
pages and file pages.
Link: https://lkml.kernel.org/r/20220813080757.59131-1-yang.yang29@zte.com.cn
Fixes: 170b04b7ae4963 ("mm/workingset: prepare the workingset detection infrastructure for anon LRU")
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The parameter 'struct damon_ctx *ctx' is unnecessary in damon region split
operation, so we can remove it.
Link: https://lkml.kernel.org/r/1660403943-29124-1-git-send-email-kaixuxia@tencent.com
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The -f option is to filter out the information of blocks whose memory has
not been released, I noticed some blocks should not be filtered out.
Commit 9cc7e96aa846 ("mm/page_owner: record timestamp and pid") records
the allocation timestamp (ts_nsec) of all pages.
Commit 866b48526217 ("mm/page_owner: record the timestamp of all pages
during free") records the free timestamp (free_ts_nsec) of all pages.
When the page is allocated for the first time, the initial value of
free_ts_nsec is 0, and the corresponding time will be obtained when the
page is released. But during reallocation the free_ts_nsec will not reset
to 0 again. In particular, when page migration occurs, these two
timestamps will be the same.
Now page_owner_sort removes all text blocks whose free_ts_nsec is not 0
when using -f option. However, this way can only select pages allocated
for the first time. If a freed page is reallocated, free_ts_nsec will be
less than ts_nsec; if page migration occurs, the two timestamps will be
equal. These cases should be considered as pages are not released.
So I fix the function is_need() to keep text blocks that meet the above
two conditions when using -f option.
Link: https://lkml.kernel.org/r/20220812155515.30846-1-caoyixuan2019@email.szu.edu.cn
Signed-off-by: Yixuan Cao <caoyixuan2019@email.szu.edu.cn>
Cc: Chongxi Zhao <zhaochongxi2019@email.szu.edu.cn>
Cc: Jiajian Ye <yejiajian2018@email.szu.edu.cn>
Cc: Yuhong Feng <yuhongf@szu.edu.cn>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Georgi Djakov <georgi.djakov@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
folio_test_hugetlb() will call PageHeadHuge which is a function call,
and blocks the compiler from recognizing this redundant load.
After rearranging the code, stack usage is dropped from 32 to 24, and
the function size is smaller (tested on GCC 12):
Before:
Stack usage:
mm/util.c:845:5:folio_mapcount 32 static
Size:
0000000000000ea0 00000000000000c7 T folio_mapcount
After:
Stack usage:
mm/util.c:845:5:folio_mapcount 24 static
Size:
0000000000000ea0 00000000000000b0 T folio_mapcount
Link: https://lkml.kernel.org/r/20220801173155.92008-1-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
It seems unnecessary to search pages with order < alloc_order in
fallback allocation.
This can currently happen with ALLOC_NOFRAGMENT and alloc_order >
pageblock_order, so add a test to prevent it.
[vbabka@suse.cz: changelog addition]
Link: https://lkml.kernel.org/r/20220803025121.47018-1-wuyun.abel@bytedance.com
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The allocation address of the table pointer variable is first performed in
the function, no initialization assignment is required, and no invalid
pointer will appear.
Link: https://lkml.kernel.org/r/20220803064118.3664-1-kunyu@nfschina.com
Signed-off-by: Li kunyu <kunyu@nfschina.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song found that after MPOL_PREFERRED_MANY policy was introduced in
commit b27abaccf8e8 ("mm/mempolicy: add MPOL_PREFERRED_MANY for multiple
preferred nodes"), the policy_nodemask_current()'s semantics for this new
policy has been changed, which returns 'preferred' nodes instead of
'allowed' nodes.
With the changed semantic of policy_nodemask_current, a task with
MPOL_PREFERRED_MANY policy could fail to get its reservation even though
it can fall back to other nodes (either defined by cpusets or all online
nodes) for that reservation failing mmap calles unnecessarily early.
The fix is to not consider MPOL_PREFERRED_MANY for reservations at all
because they, unlike MPOL_MBIND, do not pose any actual hard constrain.
Michal suggested the policy_nodemask_current() is only used by hugetlb,
and could be moved to hugetlb code with more explicit name to enforce the
'allowed' semantics for which only MPOL_BIND policy matters.
apply_policy_zone() is made extern to be called in hugetlb code and its
return value is changed to bool.
[1]. https://lore.kernel.org/lkml/20220801084207.39086-1-songmuchun@bytedance.com/t/
Link: https://lkml.kernel.org/r/20220805005903.95563-1-feng.tang@intel.com
Fixes: b27abaccf8e8 ("mm/mempolicy: add MPOL_PREFERRED_MANY for multiple preferred nodes")
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reported-by: Muchun Song <songmuchun@bytedance.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Ben Widawsky <bwidawsk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The mems_allowed field can be modified by other tasks, so it isn't safe to
access it with alloc_lock unlocked even in the current process context.
Say there are two tasks: A from cpusetA is performing set_mempolicy(2),
and B is changing cpusetA's cpuset.mems:
A (set_mempolicy) B (echo xx > cpuset.mems)
-------------------------------------------------------
pol = mpol_new();
update_tasks_nodemask(cpusetA) {
foreach t in cpusetA {
cpuset_change_task_nodemask(t) {
mpol_set_nodemask(pol) {
task_lock(t); // t could be A
new = f(A->mems_allowed);
update t->mems_allowed;
pol.create(pol, new);
task_unlock(t);
}
}
}
}
task_lock(A);
A->mempolicy = pol;
task_unlock(A);
In this case A's pol->nodes is computed by old mems_allowed, and could
be inconsistent with A's new mems_allowed.
While it is different when replacing vmas' policy: the pol->nodes is
gone wild only when current_cpuset_is_being_rebound():
A (mbind) B (echo xx > cpuset.mems)
-------------------------------------------------------
pol = mpol_new();
mmap_write_lock(A->mm);
cpuset_being_rebound = cpusetA;
update_tasks_nodemask(cpusetA) {
foreach t in cpusetA {
cpuset_change_task_nodemask(t) {
mpol_set_nodemask(pol) {
task_lock(t); // t could be A
mask = f(A->mems_allowed);
update t->mems_allowed;
pol.create(pol, mask);
task_unlock(t);
}
}
foreach v in A->mm {
if (cpuset_being_rebound == cpusetA)
pol.rebind(pol, cpuset.mems);
v->vma_policy = pol;
}
mmap_write_unlock(A->mm);
mmap_write_lock(t->mm);
mpol_rebind_mm(t->mm);
mmap_write_unlock(t->mm);
}
}
cpuset_being_rebound = NULL;
In this case, the cpuset.mems, which has already done updating, is finally
used for calculating pol->nodes, rather than A->mems_allowed. So it is OK
to call mpol_set_nodemask() with alloc_lock unlocked when doing mbind(2).
Link: https://lkml.kernel.org/r/20220811124157.74888-1-wuyun.abel@bytedance.com
Fixes: 78b132e9bae9 ("mm/mempolicy: remove or narrow the lock on current")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently only 12 characters of the cma name is being used as the debug
directories where as the cma name can be of length CMA_MAX_NAME(=64)
characters. One side problem with this is having 2 cma's with first
common 12 characters would end up in trying to create directories with
same name and fails with -EEXIST thus can limit cma debug functionality.
The 'cma-' prefix is used initially where cma areas don't have any names
and are represented by simple integer values. Since now each cma would be
having its own name, drop 'cma-' prefix for the cma debug directories as
they are clearly evident that they are for cma debug through creating them
in /sys/kernel/debug/cma/ path.
Link: https://lkml.kernel.org/r/1660223729-22461-1-git-send-email-quic_charante@quicinc.com
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Pavan Kondeti <quic_pkondeti@quicinc.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The argument is always set to end_swap_bio_write, so remove the argument
and mark end_swap_bio_write static.
Link: https://lkml.kernel.org/r/20220811141741.660214-1-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
pool->size_class array elements can't be NULL, so this check
is not needed.
In the whole code, we assign pool->size_class[i] values that are
not NULL. Releasing memory for these values occurs in the
zs_destroy_pool() function, which also releases and destroys the pool.
In addition, in the zs_stats_size_show() and async_free_zspage(),
with similar iterations over the array, we don't check it for NULL
pointer.
Link: https://lkml.kernel.org/r/20220811153755.16102-3-avromanov@sberdevices.ru
Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "tidy up zsmalloc implementation"
This patchset remove some unnecessary checks and adds a clarifying
comment. While analysing zs_object_copy() function code, I spent some
time to understand what the call kunmap_atomic(d_addr) is for. It seems
that this point is not trivial and it is worth adding a comment.
This patch (of 2):
It's not obvious why kunmap_atomic(d_addr) call is needed.
[akpm@linux-foundation.org: tweak comment layout]
Link: https://lkml.kernel.org/r/20220811153755.16102-1-avromanov@sberdevices.ru
Link: https://lkml.kernel.org/r/20220811153755.16102-2-avromanov@sberdevices.ru
Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The magic number 0 and 1 are used in several places in vmscan.c.
Define macros for them to improve code readability.
Link: https://lkml.kernel.org/r/20220808005644.1721066-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This new mode was recently added to the userfaultfd selftest. We want to
exercise both userfaultfd(2) as well as /dev/userfaultfd, so add both
test cases to the script.
Link: https://lkml.kernel.org/r/20220808175614.3885028-6-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Explain the different ways to create a new userfaultfd, and how access
control works for each way.
[axelrasmussen@google.com: improve wording in documentation, per Mike]
Link: https://lkml.kernel.org/r/20220819205201.658693-5-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20220808175614.3885028-5-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We clearly want to ensure both userfaultfd(2) and /dev/userfaultfd keep
working into the future, so just run the test twice, using each interface.
Instead of always testing both userfaultfd(2) and /dev/userfaultfd, let
the user choose which to test.
As with other test features, change the behavior based on a new command
line flag. Introduce the idea of "test mods", which are generic (not
specific to a test type) modifications to the behavior of the test. This
is sort of borrowed from this RFC patch series [1], but simplified a bit.
The benefit is, in "typical" configurations this test is somewhat slow
(say, 30sec or something). Testing both clearly doubles it, so it may not
always be desirable, as users are likely to use one or the other, but
never both, in the "real world".
[1]: https://patchwork.kernel.org/project/linux-mm/patch/20201129004548.1619714-14-namit@vmware.com/
[axelrasmussen@google.com: modify selftest to exit with KSFT_SKIP *only* when features are unsupported, per Mike]
Link: https://lkml.kernel.org/r/20220819205201.658693-4-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20220808175614.3885028-4-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Historically, it has been shown that intercepting kernel faults with
userfaultfd (thereby forcing the kernel to wait for an arbitrary amount of
time) can be exploited, or at least can make some kinds of exploits
easier. So, in 37cd0575b8 "userfaultfd: add UFFD_USER_MODE_ONLY" we
changed things so, in order for kernel faults to be handled by
userfaultfd, either the process needs CAP_SYS_PTRACE, or this sysctl must
be configured so that any unprivileged user can do it.
In a typical implementation of a hypervisor with live migration (take
QEMU/KVM as one such example), we do indeed need to be able to handle
kernel faults. But, both options above are less than ideal:
- Toggling the sysctl increases attack surface by allowing any
unprivileged user to do it.
- Granting the live migration process CAP_SYS_PTRACE gives it this
ability, but *also* the ability to "observe and control the
execution of another process [...], and examine and change [its]
memory and registers" (from ptrace(2)). This isn't something we need
or want to be able to do, so granting this permission violates the
"principle of least privilege".
This is all a long winded way to say: we want a more fine-grained way to
grant access to userfaultfd, without granting other additional permissions
at the same time.
To achieve this, add a /dev/userfaultfd misc device. This device provides
an alternative to the userfaultfd(2) syscall for the creation of new
userfaultfds. The idea is, any userfaultfds created this way will be able
to handle kernel faults, without the caller having any special
capabilities. Access to this mechanism is instead restricted using e.g.
standard filesystem permissions.
[axelrasmussen@google.com: Handle misc_register() failure properly]
Link: https://lkml.kernel.org/r/20220819205201.658693-3-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20220808175614.3885028-3-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Nadav Amit <namit@vmware.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "userfaultfd: add /dev/userfaultfd for fine grained access
control", v7.
Why not ...?
============
- Why not /proc/[pid]/userfaultfd? Two main points (additional discussion [1]):
- /proc/[pid]/* files are all owned by the user/group of the process, and
they don't really support chmod/chown. So, without extending procfs it
doesn't solve the problem this series is trying to solve.
- The main argument *for* this was to support creating UFFDs for remote
processes. But, that use case clearly calls for CAP_SYS_PTRACE, so to
support this we could just use the UFFD syscall as-is.
- Why not use a syscall? Access to syscalls is generally controlled by
capabilities. We don't have a capability which is used for userfaultfd access
without also granting more / other permissions as well, and adding a new
capability was rejected [2].
- It's possible a LSM could be used to control access instead, but I have
some concerns. I don't think this approach would be as easy to use,
particularly if we were to try to solve this with something heavyweight
like SELinux. Maybe we could pursue adding a new LSM specifically for
this user case, but it may be too narrow of a case to justify that.
[1]: https://patchwork.kernel.org/project/linux-mm/cover/20220719195628.3415852-1-axelrasmussen@google.com/
[2]: https://lore.kernel.org/lkml/686276b9-4530-2045-6bd8-170e5943abe4@schaufler-ca.com/T/
This patch (of 5):
This not being included was just a simple oversight. There are certain
features (like minor fault support) which are only enabled on shared
mappings, so without including hugetlb_shared we actually lose a
significant amount of test coverage.
Link: https://lkml.kernel.org/r/20220808175614.3885028-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20220808175614.3885028-2-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Use kmalloc(...) rather than kmalloc_array(1, ...) because the number of
elements we are specifying in this case is 1, kmalloc would accomplish the
same thing and we can simplify.
Link: https://lkml.kernel.org/r/20220808220019.1680469-1-klee33@uw.edu
Signed-off-by: Kenneth Lee <klee33@uw.edu>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since commit 5d1fd5dc877b ("mm,hwpoison: introduce MF_MSG_UNSPLIT_THP"),
the action_result(,MF_MSG_UNSPLIT_THP,) called to show memory error event
in memory_failure(), so the pr_info() in try_to_split_thp_page() is only
needed in soft_offline_in_use_page().
Meanwhile this could also fix the unexpected prefix for "thp split failed"
due to commit 96f96763de26 ("mm: memory-failure: convert to pr_fmt()").
Link: https://lkml.kernel.org/r/20220809111813.139690-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Align larger anonymous memory mappings on THP boundaries by going through
thp_get_unmapped_area if THPs are enabled for the current process.
With this patch, larger anonymous mappings are now THP aligned. When a
malloc library allocates a 2MB or larger arena, that arena can now be
mapped with THPs right from the start, which can result in better TLB hit
rates and execution time.
Link: https://lkml.kernel.org/r/20220809142457.4751229f@imladris.surriel.com
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Remove unused variable 'nid' in offline_page_ext(). This is not used
since the page_ext code inception.
Link: https://lkml.kernel.org/r/1659330397-11817-1-git-send-email-quic_charante@quicinc.com
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Pavan Kondeti <quic_pkondeti@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add support to allocate and verify collapse of multiple hugepage-sized
regions into multiple THPs.
Add "nr" argument to check_huge() that instructs check_huge() to check for
exactly "nr_hpages" THPs. This has the added benefit of now being able to
check for exactly 0 THPs, and so callsites that previously checked the
negation of exactly 1 THP are now more correct.
->collapse struct collapse_context hook has been expanded with a
"nr_hpages" argument to collapse "nr_hpages" hugepages. The
collapse_full() test has been repurposed to collapse 4 THPs at once. It
is expected more tests will want to test multi THP collapse (e.g.
file/shmem).
This is of particular benefit to madvise collapse context given that it
may do many THP collapses during a single syscall.
Link: https://lkml.kernel.org/r/20220706235936.2197195-19-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add selftest specific to madvise collapse context that tests MADV_COLLAPSE
is "successful" if a hugepage-aligned/sized region is already pmd-mapped.
This test also verifies that MADV_COLLAPSE can collapse memory into THPs
even in "madvise" THP mode and the memory isn't marked VM_HUGEPAGE.
Link: https://lkml.kernel.org/r/20220706235936.2197195-18-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add madvise collapse context to hugepage collapse selftests. This context
is tested with /sys/kernel/mm/transparent_hugepage/enabled set to "never"
in order to avoid unwanted interaction with khugepaged during testing.
Also, refactor updates to sysfs THP settings using a stack so that the THP
settings from nested callers can be restored.
Link: https://lkml.kernel.org/r/20220706235936.2197195-17-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The code
p = alloc_mapping();
printf("Allocate huge page...");
madvise(p, hpage_pmd_size, MADV_HUGEPAGE);
fill_memory(p, 0, hpage_pmd_size);
if (check_huge(p))
success("OK");
else
fail("Fail");
Is repeated many times in different tests. Add a helper, alloc_hpage()
to handle this.
Link: https://lkml.kernel.org/r/20220706235936.2197195-16-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Modularize the collapse action of khugepaged collapse selftests by
introducing a struct collapse_context which specifies how to collapse a
given memory range and the expected semantics of the collapse. This can
be reused later to test other collapse contexts.
Additionally, all tests have logic that checks if a collapse occurred via
reading /proc/self/smaps, and report if this is different than expected.
Move this logic into the per-context ->collapse() hook instead of
repeating it in every test.
Link: https://lkml.kernel.org/r/20220706235936.2197195-15-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Allow MADV_COLLAPSE behavior for process_madvise(2) if caller has
CAP_SYS_ADMIN or is requesting collapse of it's own memory.
This is useful for the development of userspace agents that seek to
optimize THP utilization system-wide by using userspace signals to
prioritize what memory is most deserving of being THP-backed.
[zokeefe@google.com: remove CAP_SYS_ADMIN requirement for process_madvise(MADV_COLLAPSE)]
Link: https://lkml.kernel.org/r/20220801210946.3069083-1-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-13-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The following functions are shared between khugepaged and madvise collapse
contexts. Replace the "khugepaged_" prefix with generic "hpage_collapse_"
prefix in such cases:
khugepaged_test_exit() -> hpage_collapse_test_exit()
khugepaged_scan_abort() -> hpage_collapse_scan_abort()
khugepaged_scan_pmd() -> hpage_collapse_scan_pmd()
khugepaged_find_target_node() -> hpage_collapse_find_target_node()
khugepaged_alloc_page() -> hpage_collapse_alloc_page()
The kerenel ABI (e.g. huge_memory:mm_khugepaged_scan_pmd tracepoint) is
unaltered.
Link: https://lkml.kernel.org/r/20220706235936.2197195-11-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This idea was introduced by David Rientjes[1].
Introduce a new madvise mode, MADV_COLLAPSE, that allows users to request
a synchronous collapse of memory at their own expense.
The benefits of this approach are:
* CPU is charged to the process that wants to spend the cycles for the
THP
* Avoid unpredictable timing of khugepaged collapse
Semantics
This call is independent of the system-wide THP sysfs settings, but will
fail for memory marked VM_NOHUGEPAGE. If the ranges provided span
multiple VMAs, the semantics of the collapse over each VMA is independent
from the others. This implies a hugepage cannot cross a VMA boundary. If
collapse of a given hugepage-aligned/sized region fails, the operation may
continue to attempt collapsing the remainder of memory specified.
The memory ranges provided must be page-aligned, but are not required to
be hugepage-aligned. If the memory ranges are not hugepage-aligned, the
start/end of the range will be clamped to the first/last hugepage-aligned
address covered by said range. The memory ranges must span at least one
hugepage-sized region.
All non-resident pages covered by the range will first be
swapped/faulted-in, before being internally copied onto a freshly
allocated hugepage. Unmapped pages will have their data directly
initialized to 0 in the new hugepage. However, for every eligible
hugepage aligned/sized region to-be collapsed, at least one page must
currently be backed by memory (a PMD covering the address range must
already exist).
Allocation for the new hugepage may enter direct reclaim and/or
compaction, regardless of VMA flags. When the system has multiple NUMA
nodes, the hugepage will be allocated from the node providing the most
native pages. This operation operates on the current state of the
specified process and makes no persistent changes or guarantees on how
pages will be mapped, constructed, or faulted in the future
Return Value
If all hugepage-sized/aligned regions covered by the provided range were
either successfully collapsed, or were already PMD-mapped THPs, this
operation will be deemed successful. On success, process_madvise(2)
returns the number of bytes advised, and madvise(2) returns 0. Else, -1
is returned and errno is set to indicate the error for the most-recently
attempted hugepage collapse. Note that many failures might have occurred,
since the operation may continue to collapse in the event a single
hugepage-sized/aligned region fails.
ENOMEM Memory allocation failed or VMA not found
EBUSY Memcg charging failed
EAGAIN Required resource temporarily unavailable. Try again
might succeed.
EINVAL Other error: No PMD found, subpage doesn't have Present
bit set, "Special" page no backed by struct page, VMA
incorrectly sized, address not page-aligned, ...
Most notable here is ENOMEM and EBUSY (new to madvise) which are intended
to provide the caller with actionable feedback so they may take an
appropriate fallback measure.
Use Cases
An immediate user of this new functionality are malloc() implementations
that manage memory in hugepage-sized chunks, but sometimes subrelease
memory back to the system in native-sized chunks via MADV_DONTNEED;
zapping the pmd. Later, when the memory is hot, the implementation could
madvise(MADV_COLLAPSE) to re-back the memory by THPs to regain hugepage
coverage and dTLB performance. TCMalloc is such an implementation that
could benefit from this[2].
Only privately-mapped anon memory is supported for now, but additional
support for file, shmem, and HugeTLB high-granularity mappings[2] is
expected. File and tmpfs/shmem support would permit:
* Backing executable text by THPs. Current support provided by
CONFIG_READ_ONLY_THP_FOR_FS may take a long time on a large system which
might impair services from serving at their full rated load after
(re)starting. Tricks like mremap(2)'ing text onto anonymous memory to
immediately realize iTLB performance prevents page sharing and demand
paging, both of which increase steady state memory footprint. With
MADV_COLLAPSE, we get the best of both worlds: Peak upfront performance
and lower RAM footprints.
* Backing guest memory by hugapages after the memory contents have been
migrated in native-page-sized chunks to a new host, in a
userfaultfd-based live-migration stack.
[1] https://lore.kernel.org/linux-mm/d098c392-273a-36a4-1a29-59731cdf5d3d@google.com/
[2] https://github.com/google/tcmalloc/tree/master/tcmalloc
[jrdr.linux@gmail.com: avoid possible memory leak in failure path]
Link: https://lkml.kernel.org/r/20220713024109.62810-1-jrdr.linux@gmail.com
[zokeefe@google.com add missing kfree() to madvise_collapse()]
Link: https://lore.kernel.org/linux-mm/20220713024109.62810-1-jrdr.linux@gmail.com/
Link: https://lkml.kernel.org/r/20220713161851.1879439-1-zokeefe@google.com
[zokeefe@google.com: delay computation of hpage boundaries until use]]
Link: https://lkml.kernel.org/r/20220720140603.1958773-4-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-10-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Suggested-by: David Rientjes <rientjes@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When scanning an anon pmd to see if it's eligible for collapse, return
SCAN_PMD_MAPPED if the pmd already maps a hugepage. Note that
SCAN_PMD_MAPPED is different from SCAN_PAGE_COMPOUND used in the
file-collapse path, since the latter might identify pte-mapped compound
pages. This is required by MADV_COLLAPSE which necessarily needs to know
what hugepage-aligned/sized regions are already pmd-mapped.
In order to determine if a pmd already maps a hugepage, refactor
mm_find_pmd():
Return mm_find_pmd() to it's pre-commit f72e7dcdd252 ("mm: let mm_find_pmd
fix buggy race with THP fault") behavior. ksm was the only caller that
explicitly wanted a pte-mapping pmd, so open code the pte-mapping logic
there (pmd_present() and pmd_trans_huge() checks).
Undo revert change in commit f72e7dcdd252 ("mm: let mm_find_pmd fix buggy
race with THP fault") that open-coded split_huge_pmd_address() pmd lookup
and use mm_find_pmd() instead.
Link: https://lkml.kernel.org/r/20220706235936.2197195-9-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
MADV_COLLAPSE is not coupled to the kernel-oriented sysfs THP settings[1].
hugepage_vma_check() is the authority on determining if a VMA is eligible
for THP allocation/collapse, and currently enforces the sysfs THP
settings. Add a flag to disable these checks. For now, only apply this
arg to anon and file, which use /sys/kernel/transparent_hugepage/enabled.
We can expand this to shmem, which uses
/sys/kernel/transparent_hugepage/shmem_enabled, later.
Use this flag in collapse_pte_mapped_thp() where previously the VMA flags
passed to hugepage_vma_check() were OR'd with VM_HUGEPAGE to elide the
VM_HUGEPAGE check in "madvise" THP mode. Prior to "mm: khugepaged: check
THP flag in hugepage_vma_check()", this check also didn't check "never"
THP mode. As such, this restores the previous behavior of
collapse_pte_mapped_thp() where sysfs THP settings are ignored. See
comment in code for justification why this is OK.
[1] https://lore.kernel.org/linux-mm/CAAa6QmQxay1_=Pmt8oCX2-Va18t44FV-Vs-WsQt_6+qBks4nZA@mail.gmail.com/
Link: https://lkml.kernel.org/r/20220706235936.2197195-8-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add .is_khugepaged flag to struct collapse_control so khugepaged-specific
behavior can be elided by MADV_COLLAPSE context.
Start by protecting khugepaged-specific heuristics by this flag. In
MADV_COLLAPSE, the user presumably has reason to believe the collapse will
be beneficial and khugepaged heuristics shouldn't prevent the user from
doing so:
1) sysfs-controlled knobs khugepaged_max_ptes_[none|swap|shared]
2) requirement that some pages in region being collapsed be young or
referenced
[zokeefe@google.com: consistently order cc->is_khugepaged and pte_* checks]
Link: https://lkml.kernel.org/r/20220720140603.1958773-3-zokeefe@google.com
Link: https://lore.kernel.org/linux-mm/Ys2qJm6FaOQcxkha@google.com/
Link: https://lkml.kernel.org/r/20220706235936.2197195-7-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Propagate enum scan_result codes back through return values of
functions downstream of khugepaged_scan_file() and
khugepaged_scan_pmd() to inform callers if the operation was
successful, and if not, why.
Since khugepaged_scan_pmd()'s return value already has a specific meaning
(whether mmap_lock was unlocked or not), add a bool* argument to
khugepaged_scan_pmd() to retrieve this information.
Change khugepaged to take action based on the return values of
khugepaged_scan_file() and khugepaged_scan_pmd() instead of acting deep
within the collapsing functions themselves.
hugepage_vma_revalidate() now returns SCAN_SUCCEED on success to be more
consistent with enum scan_result propagation.
Remove dependency on error pointers to communicate to khugepaged that
allocation failed and it should sleep; instead just use the result of the
scan (SCAN_ALLOC_HUGE_PAGE_FAIL if allocation fails).
Link: https://lkml.kernel.org/r/20220706235936.2197195-6-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The following code is duplicated in collapse_huge_page() and
collapse_file():
gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE;
new_page = khugepaged_alloc_page(hpage, gfp, node);
if (!new_page) {
result = SCAN_ALLOC_HUGE_PAGE_FAIL;
goto out;
}
if (unlikely(mem_cgroup_charge(page_folio(new_page), mm, gfp))) {
result = SCAN_CGROUP_CHARGE_FAIL;
goto out;
}
count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC);
Also, "node" is passed as an argument to both collapse_huge_page() and
collapse_file() and obtained the same way, via
khugepaged_find_target_node().
Move all this into a new helper, alloc_charge_hpage(), and remove the
duplicate code from collapse_huge_page() and collapse_file(). Also,
simplify khugepaged_alloc_page() by returning a bool indicating allocation
success instead of a copy of the allocated struct page *.
Link: https://lkml.kernel.org/r/20220706235936.2197195-5-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Suggested-by: Peter Xu <peterx@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Modularize hugepage collapse by introducing struct collapse_control. This
structure serves to describe the properties of the requested collapse, as
well as serve as a local scratch pad to use during the collapse itself.
Start by moving global per-node khugepaged statistics into this new
structure. Note that this structure is still statically allocated since
CONFIG_NODES_SHIFT might be arbitrary large, and stack-allocating a
MAX_NUMNODES-sized array could cause -Wframe-large-than= errors.
[zokeefe@google.com: use minimal bits to store num page < HPAGE_PMD_NR]
Link: https://lkml.kernel.org/r/20220720140603.1958773-2-zokeefe@google.com
Link: https://lore.kernel.org/linux-mm/Ys2CeIm%2FQmQwWh9a@google.com/
[sfr@canb.auug.org.au: fix build]
Link: https://lkml.kernel.org/r/20220721195508.15f1e07a@canb.auug.org.au
[zokeefe@google.com: fix struct collapse_control load_node definition]
Link: https://lore.kernel.org/linux-mm/202209021349.F73i5d6X-lkp@intel.com/
Link: https://lkml.kernel.org/r/20220903021221.1130021-1-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-4-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: userspace hugepage collapse", v7.
Introduction
--------------------------------
This series provides a mechanism for userspace to induce a collapse of
eligible ranges of memory into transparent hugepages in process context,
thus permitting users to more tightly control their own hugepage
utilization policy at their own expense.
This idea was introduced by David Rientjes[5].
Interface
--------------------------------
The proposed interface adds a new madvise(2) mode, MADV_COLLAPSE, and
leverages the new process_madvise(2) call.
process_madvise(2)
Performs a synchronous collapse of the native pages
mapped by the list of iovecs into transparent hugepages.
This operation is independent of the system THP sysfs settings,
but attempts to collapse VMAs marked VM_NOHUGEPAGE will still fail.
THP allocation may enter direct reclaim and/or compaction.
When a range spans multiple VMAs, the semantics of the collapse
over of each VMA is independent from the others.
Caller must have CAP_SYS_ADMIN if not acting on self.
Return value follows existing process_madvise(2) conventions. A
“success” indicates that all hugepage-sized/aligned regions
covered by the provided range were either successfully
collapsed, or were already pmd-mapped THPs.
madvise(2)
Equivalent to process_madvise(2) on self, with 0 returned on
“success”.
Current Use-Cases
--------------------------------
(1) Immediately back executable text by THPs. Current support provided
by CONFIG_READ_ONLY_THP_FOR_FS may take a long time on a large
system which might impair services from serving at their full rated
load after (re)starting. Tricks like mremap(2)'ing text onto
anonymous memory to immediately realize iTLB performance prevents
page sharing and demand paging, both of which increase steady state
memory footprint. With MADV_COLLAPSE, we get the best of both
worlds: Peak upfront performance and lower RAM footprints. Note
that subsequent support for file-backed memory is required here.
(2) malloc() implementations that manage memory in hugepage-sized
chunks, but sometimes subrelease memory back to the system in
native-sized chunks via MADV_DONTNEED; zapping the pmd. Later,
when the memory is hot, the implementation could
madvise(MADV_COLLAPSE) to re-back the memory by THPs to regain
hugepage coverage and dTLB performance. TCMalloc is such an
implementation that could benefit from this[6]. A prior study of
Google internal workloads during evaluation of Temeraire, a
hugepage-aware enhancement to TCMalloc, showed that nearly 20% of
all cpu cycles were spent in dTLB stalls, and that increasing
hugepage coverage by even small amount can help with that[7].
(3) userfaultfd-based live migration of virtual machines satisfy UFFD
faults by fetching native-sized pages over the network (to avoid
latency of transferring an entire hugepage). However, after guest
memory has been fully copied to the new host, MADV_COLLAPSE can
be used to immediately increase guest performance. Note that
subsequent support for file/shmem-backed memory is required here.
(4) HugeTLB high-granularity mapping allows HugeTLB a HugeTLB page to
be mapped at different levels in the page tables[8]. As it's not
"transparent" like THP, HugeTLB high-granularity mappings require
an explicit user API. It is intended that MADV_COLLAPSE be co-opted
for this use case[9]. Note that subsequent support for HugeTLB
memory is required here.
Future work
--------------------------------
Only private anonymous memory is supported by this series. File and
shmem memory support will be added later.
One possible user of this functionality is a userspace agent that
attempts to optimize THP utilization system-wide by allocating THPs
based on, for example, task priority, task performance requirements, or
heatmaps. For the latter, one idea that has already surfaced is using
DAMON to identify hot regions, and driving THP collapse through a new
DAMOS_COLLAPSE scheme[10].
This patch (of 17):
The khugepaged has optimization to reduce huge page allocation calls for
!CONFIG_NUMA by carrying the allocated but failed to collapse huge page to
the next loop. CONFIG_NUMA doesn't do so since the next loop may try to
collapse huge page from a different node, so it doesn't make too much
sense to carry it.
But when NUMA=n, the huge page is allocated by khugepaged_prealloc_page()
before scanning the address space, so it means huge page may be allocated
even though there is no suitable range for collapsing. Then the page
would be just freed if khugepaged already made enough progress. This
could make NUMA=n run have 5 times as much thp_collapse_alloc as NUMA=y
run. This problem actually makes things worse due to the way more
pointless THP allocations and makes the optimization pointless.
This could be fixed by carrying the huge page across scans, but it will
complicate the code further and the huge page may be carried indefinitely.
But if we take one step back, the optimization itself seems not worth
keeping nowadays since:
* Not too many users build NUMA=n kernel nowadays even though the kernel is
actually running on a non-NUMA machine. Some small devices may run NUMA=n
kernel, but I don't think they actually use THP.
* Since commit 44042b449872 ("mm/page_alloc: allow high-order pages to be
stored on the per-cpu lists"), THP could be cached by pcp. This actually
somehow does the job done by the optimization.
Link: https://lkml.kernel.org/r/20220706235936.2197195-1-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-3-zokeefe@google.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Co-developed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
cc:stable, addressing pre-6.0 issues.
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Merge tag 'mm-hotfixes-stable-2022-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull more hotfixes from Andrew Morton:
"Seventeen hotfixes. Mostly memory management things.
Ten patches are cc:stable, addressing pre-6.0 issues"
* tag 'mm-hotfixes-stable-2022-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
.mailmap: update Luca Ceresoli's e-mail address
mm/mprotect: only reference swap pfn page if type match
squashfs: don't call kmalloc in decompressors
mm/damon/dbgfs: avoid duplicate context directory creation
mailmap: update email address for Colin King
asm-generic: sections: refactor memory_intersects
bootmem: remove the vmemmap pages from kmemleak in put_page_bootmem
ocfs2: fix freeing uninitialized resource on ocfs2_dlm_shutdown
Revert "memcg: cleanup racy sum avoidance code"
mm/zsmalloc: do not attempt to free IS_ERR handle
binder_alloc: add missing mmap_lock calls when using the VMA
mm: re-allow pinning of zero pfns (again)
vmcoreinfo: add kallsyms_num_syms symbol
mailmap: update Guilherme G. Piccoli's email addresses
writeback: avoid use-after-free after removing device
shmem: update folio if shmem_replace_page() updates the page
mm/hugetlb: avoid corrupting page->mapping in hugetlb_mcopy_atomic_pte
Hi Linus,
Please pull (hopefully) the last portion of fixes from Sander for his
UP rework series. The original series came from -mm tree, and it was
not the latest version, that's why we need follow-ups. It fixes only
a test introduced by that series. The test fails under certain configs.
From Sander:
This series fixes the reported issues, and implements the suggested
improvements, for the version of the cpumask tests [1] that was merged
with commit c41e8866c28c ("lib/test: introduce cpumask KUnit test
suite").
These changes include fixes for the tests, and better alignment with the
KUnit style guidelines.
Thanks,
Yury
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Merge tag 'bitmap-6.0-rc3' of github.com:/norov/linux
Pull bitmap fixes from Yury Norov:
"Fix the reported issues, and implements the suggested improvements,
for the version of the cpumask tests [1] that was merged with commit
c41e8866c28c ("lib/test: introduce cpumask KUnit test suite").
These changes include fixes for the tests, and better alignment with
the KUnit style guidelines"
* tag 'bitmap-6.0-rc3' of github.com:/norov/linux:
lib/cpumask_kunit: add tests file to MAINTAINERS
lib/cpumask_kunit: log mask contents
lib/test_cpumask: follow KUnit style guidelines
lib/test_cpumask: fix cpu_possible_mask last test
lib/test_cpumask: drop cpu_possible_mask full test
My Bootlin address is preferred from now on.
Link: https://lkml.kernel.org/r/20220826130515.3011951-1-luca.ceresoli@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Atish Patra <atishp@atishpatra.org>
Cc: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The decompressors may be called while in an atomic section. So move the
kmalloc() out of this path, and into the "page actor" init function.
This fixes a regression introduced by commit
f268eedddf35 ("squashfs: extend "page actor" to handle missing pages")
Link: https://lkml.kernel.org/r/20220822215430.15933-1-phillip@squashfs.org.uk
Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages")
Reported-by: Chris Murphy <lists@colorremedies.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When user tries to create a DAMON context via the DAMON debugfs interface
with a name of an already existing context, the context directory creation
fails but a new context is created and added in the internal data
structure, due to absence of the directory creation success check. As a
result, memory could leak and DAMON cannot be turned on. An example test
case is as below:
# cd /sys/kernel/debug/damon/
# echo "off" > monitor_on
# echo paddr > target_ids
# echo "abc" > mk_context
# echo "abc" > mk_context
# echo $$ > abc/target_ids
# echo "on" > monitor_on <<< fails
Return value of 'debugfs_create_dir()' is expected to be ignored in
general, but this is an exceptional case as DAMON feature is depending
on the debugfs functionality and it has the potential duplicate name
issue. This commit therefore fixes the issue by checking the directory
creation failure and immediately return the error in the case.
Link: https://lkml.kernel.org/r/20220821180853.2400-1-sj@kernel.org
Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: Badari Pulavarty <badari.pulavarty@intel.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [ 5.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Colin King is working on kernel janitorial fixes in his spare time and
using his Intel email is confusing. Use his gmail account as the default
email address.
Link: https://lkml.kernel.org/r/20220817212753.101109-1-colin.i.king@gmail.com
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There are two problems with the current code of memory_intersects:
First, it doesn't check whether the region (begin, end) falls inside the
region (virt, vend), that is (virt < begin && vend > end).
The second problem is if vend is equal to begin, it will return true but
this is wrong since vend (virt + size) is not the last address of the
memory region but (virt + size -1) is. The wrong determination will
trigger the misreporting when the function check_for_illegal_area calls
memory_intersects to check if the dma region intersects with stext region.
The misreporting is as below (stext is at 0x80100000):
WARNING: CPU: 0 PID: 77 at kernel/dma/debug.c:1073 check_for_illegal_area+0x130/0x168
DMA-API: chipidea-usb2 e0002000.usb: device driver maps memory from kernel text or rodata [addr=800f0000] [len=65536]
Modules linked in:
CPU: 1 PID: 77 Comm: usb-storage Not tainted 5.19.0-yocto-standard #5
Hardware name: Xilinx Zynq Platform
unwind_backtrace from show_stack+0x18/0x1c
show_stack from dump_stack_lvl+0x58/0x70
dump_stack_lvl from __warn+0xb0/0x198
__warn from warn_slowpath_fmt+0x80/0xb4
warn_slowpath_fmt from check_for_illegal_area+0x130/0x168
check_for_illegal_area from debug_dma_map_sg+0x94/0x368
debug_dma_map_sg from __dma_map_sg_attrs+0x114/0x128
__dma_map_sg_attrs from dma_map_sg_attrs+0x18/0x24
dma_map_sg_attrs from usb_hcd_map_urb_for_dma+0x250/0x3b4
usb_hcd_map_urb_for_dma from usb_hcd_submit_urb+0x194/0x214
usb_hcd_submit_urb from usb_sg_wait+0xa4/0x118
usb_sg_wait from usb_stor_bulk_transfer_sglist+0xa0/0xec
usb_stor_bulk_transfer_sglist from usb_stor_bulk_srb+0x38/0x70
usb_stor_bulk_srb from usb_stor_Bulk_transport+0x150/0x360
usb_stor_Bulk_transport from usb_stor_invoke_transport+0x38/0x440
usb_stor_invoke_transport from usb_stor_control_thread+0x1e0/0x238
usb_stor_control_thread from kthread+0xf8/0x104
kthread from ret_from_fork+0x14/0x2c
Refactor memory_intersects to fix the two problems above.
Before the 1d7db834a027e ("dma-debug: use memory_intersects()
directly"), memory_intersects is called only by printk_late_init:
printk_late_init -> init_section_intersects ->memory_intersects.
There were few places where memory_intersects was called.
When commit 1d7db834a027e ("dma-debug: use memory_intersects()
directly") was merged and CONFIG_DMA_API_DEBUG is enabled, the DMA
subsystem uses it to check for an illegal area and the calltrace above
is triggered.
[akpm@linux-foundation.org: fix nearby comment typo]
Link: https://lkml.kernel.org/r/20220819081145.948016-1-quanyang.wang@windriver.com
Fixes: 979559362516 ("asm/sections: add helpers to check for section data")
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Thierry Reding <treding@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The vmemmap pages is marked by kmemleak when allocated from memblock.
Remove it from kmemleak when freeing the page. Otherwise, when we reuse
the page, kmemleak may report such an error and then stop working.
kmemleak: Cannot insert 0xffff98fb6eab3d40 into the object search tree (overlaps existing)
kmemleak: Kernel memory leak detector disabled
kmemleak: Object 0xffff98fb6be00000 (size 335544320):
kmemleak: comm "swapper", pid 0, jiffies 4294892296
kmemleak: min_count = 0
kmemleak: count = 0
kmemleak: flags = 0x1
kmemleak: checksum = 0
kmemleak: backtrace:
Link: https://lkml.kernel.org/r/20220819094005.2928241-1-liushixin2@huawei.com
Fixes: f41f2ed43ca5 (mm: hugetlb: free the vmemmap pages associated with each HugeTLB page)
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After commit 0737e01de9c4 ("ocfs2: ocfs2_mount_volume does cleanup job
before return error"), any procedure after ocfs2_dlm_init() fails will
trigger crash when calling ocfs2_dlm_shutdown().
ie: On local mount mode, no dlm resource is initialized. If
ocfs2_mount_volume() fails in ocfs2_find_slot(), error handling will call
ocfs2_dlm_shutdown(), then does dlm resource cleanup job, which will
trigger kernel crash.
This solution should bypass uninitialized resources in
ocfs2_dlm_shutdown().
Link: https://lkml.kernel.org/r/20220815085754.20417-1-heming.zhao@suse.com
Fixes: 0737e01de9c4 ("ocfs2: ocfs2_mount_volume does cleanup job before return error")
Signed-off-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Haiyue Wang
Yang Yang
Kaixu Xia
Yixuan Cao
Kairui Song
Abel Wu
Li kunyu
Feng Tang
Charan Teja Kalla
Christoph Hellwig
Alexey Romanov
Axel Rasmussen
Kenneth Lee
Shaoqin Huang
Kefeng Wang
Rik van Riel
Zach O'Keefe
Yang Shi
Linus Torvalds
Luca Ceresoli
Peter Xu
Phillip Lougher
Badari Pulavarty
Colin Ian King
Quanyang Wang
Liu Shixin
Heming Zhao