Rokudo Yan 02f768edb9 zsmalloc: account the number of compacted pages correctly
commit 2395928158059b8f9858365fce7713ce7fef62e4 upstream.

There exists multiple path may do zram compaction concurrently.
1. auto-compaction triggered during memory reclaim
2. userspace utils write zram<id>/compaction node

So, multiple threads may call zs_shrinker_scan/zs_compact concurrently.
But pages_compacted is a per zsmalloc pool variable and modification
of the variable is not serialized(through under class->lock).
There are two issues here:
1. the pages_compacted may not equal to total number of pages
freed(due to concurrently add).
2. zs_shrinker_scan may not return the correct number of pages
freed(issued by current shrinker).

The fix is simple:
1. account the number of pages freed in zs_compact locally.
2. use actomic variable pages_compacted to accumulate total number.

Link: https://lkml.kernel.org/r/20210202122235.26885-1-wu-yan@tcl.com
Fixes: 860c707dca155a56 ("zsmalloc: account the number of compacted pages")
Signed-off-by: Rokudo Yan <wu-yan@tcl.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-07 12:34:15 +01:00
..
2021-01-27 11:55:14 +01:00
2020-09-04 12:46:07 +01:00
2020-10-18 09:27:10 -07:00
2020-06-08 11:05:55 -07:00
2020-12-30 11:53:55 +01:00
2020-10-16 11:11:15 -07:00
2020-10-16 11:11:19 -07:00
2020-10-16 11:11:19 -07:00
2021-01-30 13:55:19 +01:00
2020-10-16 11:11:17 -07:00
2020-10-20 14:39:37 -07:00