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| author | Michal Hocko <mhocko@suse.com> | 2019-08-30 16:04:50 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-08-30 18:00:50 -0700 |
| commit | d2e5fb927ee7f52c1fe2a98b554881e9dffd8514 (patch) | |
| tree | 834ae6fb4e367dfccb8394c9baf84a94e262ae72 /mm/vmscan.c | |
| parent | a6c135bb1a59b5d67c8c45b214d3427d65dd7c00 (diff) | |
| download | lwn-d2e5fb927ee7f52c1fe2a98b554881e9dffd8514.tar.gz lwn-d2e5fb927ee7f52c1fe2a98b554881e9dffd8514.zip | |
mm, memcg: do not set reclaim_state on soft limit reclaim
Adric Blake has noticed[1] the following warning:
WARNING: CPU: 7 PID: 175 at mm/vmscan.c:245 set_task_reclaim_state+0x1e/0x40
[...]
Call Trace:
mem_cgroup_shrink_node+0x9b/0x1d0
mem_cgroup_soft_limit_reclaim+0x10c/0x3a0
balance_pgdat+0x276/0x540
kswapd+0x200/0x3f0
? wait_woken+0x80/0x80
kthread+0xfd/0x130
? balance_pgdat+0x540/0x540
? kthread_park+0x80/0x80
ret_from_fork+0x35/0x40
---[ end trace 727343df67b2398a ]---
which tells us that soft limit reclaim is about to overwrite the
reclaim_state configured up in the call chain (kswapd in this case but
the direct reclaim is equally possible). This means that reclaim stats
would get misleading once the soft reclaim returns and another reclaim
is done.
Fix the warning by dropping set_task_reclaim_state from the soft reclaim
which is always called with reclaim_state set up.
[1] http://lkml.kernel.org/r/CAE1jjeePxYPvw1mw2B3v803xHVR_BNnz0hQUY_JDMN8ny29M6w@mail.gmail.com
Link: http://lkml.kernel.org/r/20190828071808.20410-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Adric Blake <promarbler14@gmail.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hdanton@sina.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index c77d1e3761a7..a6c5d0b28321 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3220,6 +3220,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order, #ifdef CONFIG_MEMCG +/* Only used by soft limit reclaim. Do not reuse for anything else. */ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, gfp_t gfp_mask, bool noswap, pg_data_t *pgdat, @@ -3235,7 +3236,8 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, }; unsigned long lru_pages; - set_task_reclaim_state(current, &sc.reclaim_state); + WARN_ON_ONCE(!current->reclaim_state); + sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); @@ -3253,7 +3255,6 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); - set_task_reclaim_state(current, NULL); *nr_scanned = sc.nr_scanned; return sc.nr_reclaimed; |