diff options
| author | SJ Park <sj@kernel.org> | 2026-10-25 09:48:06 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-11-02 18:14:44 -0800 |
| commit | c4ff3ea30640b394df4156d7ddf60ad8ffe765f1 (patch) | |
| tree | fd7d2aaf57965218f3cb2725c4f6254205b1f98d /include | |
| parent | 26ae50a0901a44f7d50053f87dc38abd9f9a269c (diff) | |
mm/damon/core: move static variable rotation to damon_ctx
damon_split_some_reigons() uses a static variable, rotation, to remember
how many times it was called. It is again used to determine fair
selection of regions to split. Since it is a static variable, it can be
indeterministic and therefore less fair.
The user impact is not critical. No crash, no leak. DAMON's
best-effort and indeterministic monitoring accuracy could be slightly
more indeterministic when multiple kdamonds are used in parallel.
Fix the problem by moving the static variable into the damon_ctx struct.
Link: https://lore.kernel.org/20261025164808.152048-4-sj@kernel.org
Fixes: 1a582e6e0174 ("mm/damon/core: split a fraction of regions when nr_regions exceeds max/2")
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Closes: https://sashiko.dev/#/bug/linux-eebfcdde-2881-48ef-8df1-e2019d2a47f2
Cc: Jiayuan Chen <jiayuan.chen@shopee.com>
Cc: <stable@vger.kernel.org> # 7.3.x
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/damon.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/damon.h b/include/linux/damon.h index cb6a50032a1e..380f9cf6ddd8 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -963,6 +963,11 @@ struct damon_ctx { * for more details. */ unsigned long last_nr_regions; + /* + * number of damon_split_some_regions() invocations for this context. + * Read damon_split_some_regions() for more details. + */ + unsigned long region_split_rotation; }; /* Get a random number in [@l, @r) using @ctx's lockless PRNG. */ |