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| author | Hugh Dickins <hughd@google.com> | 2022-12-04 17:01:03 -0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-12-11 18:12:20 -0800 |
| commit | c449deb2b99ff2458214ed4a3526277bc9e40757 (patch) | |
| tree | ed92c53a9c0438b1810598e7e451b579dfa7e15a /mm/vmscan.c | |
| parent | 12a5d3955227b0d7e04fb793ccceeb2a1dd275c5 (diff) | |
| download | lwn-c449deb2b99ff2458214ed4a3526277bc9e40757.tar.gz lwn-c449deb2b99ff2458214ed4a3526277bc9e40757.zip | |
mm: memcg: fix swapcached stat accounting
I'd been worried by high "swapcached" counts in memcg OOM reports, thought
we had a problem freeing swapcache, but it was just the accounting that
was wrong.
Two issues:
1. When __remove_mapping() removes swapcache,
__delete_from_swap_cache() relies on memcg_data for the right counts to
be updated; but that had already been reset by mem_cgroup_swapout().
Swap those calls around - mem_cgroup_swapout() does not require the
swapcached flag to be set.
6.1 commit ac35a4902374 ("mm: multi-gen LRU: minimal
implementation") already made a similar swap for workingset_eviction(),
but not for this.
2. memcg's "swapcached" count was added for memcg v2 stats, but
displayed on OOM even for memcg v1: so mem_cgroup_move_account() ought
to move it.
Link: https://lkml.kernel.org/r/b8b96ee0-1e1e-85f8-df97-c82a11d7cd14@google.com
Fixes: b6038942480e ("mm: memcg: add swapcache stat for memcg v2")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 2b42ac9ad755..aba991c505f1 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1368,11 +1368,10 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio, if (folio_test_swapcache(folio)) { swp_entry_t swap = folio_swap_entry(folio); - /* get a shadow entry before mem_cgroup_swapout() clears folio_memcg() */ if (reclaimed && !mapping_exiting(mapping)) shadow = workingset_eviction(folio, target_memcg); - mem_cgroup_swapout(folio, swap); __delete_from_swap_cache(folio, swap, shadow); + mem_cgroup_swapout(folio, swap); xa_unlock_irq(&mapping->i_pages); put_swap_folio(folio, swap); } else { |