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authorHugh Dickins <hughd@google.com>2022-12-05 04:01:03 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-12-12 05:12:20 +0300
commitc449deb2b99ff2458214ed4a3526277bc9e40757 (patch)
treeed92c53a9c0438b1810598e7e451b579dfa7e15a /mm/memcontrol.c
parent12a5d3955227b0d7e04fb793ccceeb2a1dd275c5 (diff)
downloadlinux-c449deb2b99ff2458214ed4a3526277bc9e40757.tar.xz
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/memcontrol.c')
-rw-r--r--mm/memcontrol.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ff65bc23be13..ab457f0394ab 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5767,6 +5767,12 @@ static int mem_cgroup_move_account(struct page *page,
}
}
+#ifdef CONFIG_SWAP
+ if (folio_test_swapcache(folio)) {
+ __mod_lruvec_state(from_vec, NR_SWAPCACHE, -nr_pages);
+ __mod_lruvec_state(to_vec, NR_SWAPCACHE, nr_pages);
+ }
+#endif
if (folio_test_writeback(folio)) {
__mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages);
__mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages);