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mm, page_alloc: move cpuset seqcount checking to slowpath

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commit 5ce9bfef1d27944c119a397a9d827bef795487ce upstream.

This is a preparation for the following patch to make review simpler.
While the primary motivation is a bug fix, this also simplifies the fast
path, although the moved code is only enabled when cpusets are in use.

Link: http://lkml.kernel.org/r/20170120103843.24587-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Ganapatrao Kulkarni <gpkulkarni@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vlastimil Babka 2017-01-24 15:18:38 -08:00 committed by Greg Kroah-Hartman
parent d1656c5aef
commit b678e4ff7c
1 changed files with 26 additions and 21 deletions
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47
mm/page_alloc.c
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@ -3502,12 +3502,13 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
struct page *page = NULL;
unsigned int alloc_flags;
unsigned long did_some_progress;
enum compact_priority compact_priority = DEF_COMPACT_PRIORITY;
enum compact_priority compact_priority;
enum compact_result compact_result;
int compaction_retries = 0;
int no_progress_loops = 0;
int compaction_retries;
int no_progress_loops;
unsigned long alloc_start = jiffies;
unsigned int stall_timeout = 10 * HZ;
unsigned int cpuset_mems_cookie;
/*
* In the slowpath, we sanity check order to avoid ever trying to
@ -3528,6 +3529,12 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
(__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)))
gfp_mask &= ~__GFP_ATOMIC;
retry_cpuset:
compaction_retries = 0;
no_progress_loops = 0;
compact_priority = DEF_COMPACT_PRIORITY;
cpuset_mems_cookie = read_mems_allowed_begin();
/*
* The fast path uses conservative alloc_flags to succeed only until
* kswapd needs to be woken up, and to avoid the cost of setting up
@ -3699,6 +3706,15 @@ retry:
}
nopage:
/*
* When updating a task's mems_allowed, it is possible to race with
* parallel threads in such a way that an allocation can fail while
* the mask is being updated. If a page allocation is about to fail,
* check if the cpuset changed during allocation and if so, retry.
*/
if (read_mems_allowed_retry(cpuset_mems_cookie))
goto retry_cpuset;
warn_alloc(gfp_mask,
"page allocation failure: order:%u", order);
got_pg:
@ -3713,7 +3729,6 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, nodemask_t *nodemask)
{
struct page *page;
unsigned int cpuset_mems_cookie;
unsigned int alloc_flags = ALLOC_WMARK_LOW;
gfp_t alloc_mask = gfp_mask; /* The gfp_t that was actually used for allocation */
struct alloc_context ac = {
@ -3750,9 +3765,6 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
if (IS_ENABLED(CONFIG_CMA) && ac.migratetype == MIGRATE_MOVABLE)
alloc_flags |= ALLOC_CMA;
retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();
/* Dirty zone balancing only done in the fast path */
ac.spread_dirty_pages = (gfp_mask & __GFP_WRITE);
@ -3765,6 +3777,11 @@ retry_cpuset:
ac.high_zoneidx, ac.nodemask);
if (!ac.preferred_zoneref->zone) {
page = NULL;
/*
* This might be due to race with cpuset_current_mems_allowed
* update, so make sure we retry with original nodemask in the
* slow path.
*/
goto no_zone;
}
@ -3773,6 +3790,7 @@ retry_cpuset:
if (likely(page))
goto out;
no_zone:
/*
* Runtime PM, block IO and its error handling path can deadlock
* because I/O on the device might not complete.
@ -3790,24 +3808,11 @@ retry_cpuset:
ac.nodemask = nodemask;
ac.preferred_zoneref = first_zones_zonelist(ac.zonelist,
ac.high_zoneidx, ac.nodemask);
if (!ac.preferred_zoneref->zone)
goto no_zone;
/* If we have NULL preferred zone, slowpath wll handle that */
}
page = __alloc_pages_slowpath(alloc_mask, order, &ac);
no_zone:
/*
* When updating a task's mems_allowed, it is possible to race with
* parallel threads in such a way that an allocation can fail while
* the mask is being updated. If a page allocation is about to fail,
* check if the cpuset changed during allocation and if so, retry.
*/
if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) {
alloc_mask = gfp_mask;
goto retry_cpuset;
}
out:
if (memcg_kmem_enabled() && (gfp_mask & __GFP_ACCOUNT) && page &&
unlikely(memcg_kmem_charge(page, gfp_mask, order) != 0)) {