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mm:page_alloc: fix the NULL ac->nodemask in __alloc_pages_slowpath()

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should_reclaim_retry() is not ALLOC_CPUSET aware and that means that it
considers reclaimability of NUMA nodes which are outside of the cpuset. 
If other nodes have a lot of reclaimable memory then should_reclaim_retry
would instruct page allocator to retry even though there is no memory
reclaimable on the cpuset nodemask.  This is not really a huge problem
because the number of retries without any reclaim progress is bound but it
could be certainly improved.  This is a cold path so this shouldn't really
have a measurable impact on performance on most workloads.

1.Test step and the machines.
------------
root@vm:/sys/fs/cgroup/test# numactl -H | grep size
node 0 size: 9477 MB
node 1 size: 10079 MB
node 2 size: 10079 MB
node 3 size: 10078 MB

root@vm:/sys/fs/cgroup/test# cat cpuset.mems
    2

root@vm:/sys/fs/cgroup/test# stress --vm 1 --vm-bytes 12g  --vm-keep
stress: info: [33430] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd
stress: FAIL: [33430] (425) <-- worker 33431 got signal 9
stress: WARN: [33430] (427) now reaping child worker processes
stress: FAIL: [33430] (461) failed run completed in 2s

2. reclaim_retry_zone info:

We can only alloc pages from node=2, but the reclaim_retry_zone is
node=0 and return true.

root@vm:/sys/kernel/debug/tracing# cat trace
stress-33431   [001] ..... 13223.617311: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=1 wmark_check=1
stress-33431   [001] ..... 13223.617682: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=2 wmark_check=1
stress-33431   [001] ..... 13223.618103: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=3 wmark_check=1
stress-33431   [001] ..... 13223.618454: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=4 wmark_check=1
stress-33431   [001] ..... 13223.618770: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=5 wmark_check=1
stress-33431   [001] ..... 13223.619150: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=6 wmark_check=1
stress-33431   [001] ..... 13223.619510: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=7 wmark_check=1
stress-33431   [001] ..... 13223.619850: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=8 wmark_check=1
stress-33431   [001] ..... 13223.620171: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=9 wmark_check=1
stress-33431   [001] ..... 13223.620533: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=10 wmark_check=1
stress-33431   [001] ..... 13223.620894: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=11 wmark_check=1
stress-33431   [001] ..... 13223.621224: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=12 wmark_check=1
stress-33431   [001] ..... 13223.621551: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=13 wmark_check=1
stress-33431   [001] ..... 13223.621847: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=14 wmark_check=1
stress-33431   [001] ..... 13223.622200: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=15 wmark_check=1
stress-33431   [001] ..... 13223.622580: reclaim_retry_zone: node=0 zone=Normal   order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=16 wmark_check=1

With this patch, we can check the right node and get less retry in
__alloc_pages_slowpath() because there is nothing to do.

Link: https://lkml.kernel.org/r/20240822092612.3209286-1-hezhongkun.hzk@bytedance.com
Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Zhongkun He 2024-08-22 17:26:12 +08:00 committed by Andrew Morton
parent b843786b0b
commit 435b3894e7
2 changed files with 11 additions and 0 deletions
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6
mm/compaction.c
View file

@ -23,6 +23,7 @@
#include <linux/freezer.h>
#include <linux/page_owner.h>
#include <linux/psi.h>
#include <linux/cpuset.h>
#include "internal.h"
#ifdef CONFIG_COMPACTION
@ -2822,6 +2823,11 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
ac->highest_zoneidx, ac->nodemask) {
enum compact_result status;
if (cpusets_enabled() &&
(alloc_flags & ALLOC_CPUSET) &&
!__cpuset_zone_allowed(zone, gfp_mask))
continue;
if (prio > MIN_COMPACT_PRIORITY
&& compaction_deferred(zone, order)) {
rc = max_t(enum compact_result, COMPACT_DEFERRED, rc);

5
mm/page_alloc.c
View file

@ -4092,6 +4092,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
unsigned long min_wmark = min_wmark_pages(zone);
bool wmark;
if (cpusets_enabled() &&
(alloc_flags & ALLOC_CPUSET) &&
!__cpuset_zone_allowed(zone, gfp_mask))
continue;
available = reclaimable = zone_reclaimable_pages(zone);
available += zone_page_state_snapshot(zone, NR_FREE_PAGES);