Hugh Dickins c449deb2b9 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 ac35a49023 ("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: b603894248 ("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>
2022-12-11 18:12:20 -08:00
2022-11-30 15:59:01 -08:00
2022-12-11 18:12:18 -08:00
2022-09-28 09:02:20 +02:00
2022-09-28 09:02:20 +02:00
2022-09-28 09:02:20 +02:00
2022-11-06 15:07:11 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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