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| author | SeongJae Park <sj@kernel.org> | 2026-03-29 18:30:50 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-04-18 10:10:51 +0300 |
| commit | 0c13ed77dd2bc1c2d46db8ef27721213742cccd8 (patch) | |
| tree | 33a7f727befeb2fe7f51d5fa9dbff8a2060b3177 | |
| parent | 0beba407d4585a15b0dc09f2064b5b3ddcb0e857 (diff) | |
| download | linux-0c13ed77dd2bc1c2d46db8ef27721213742cccd8.tar.xz | |
Docs/admin-guide/mm/damon/lru_sort: warn commit_inputs vs param updates race
DAMON_LRU_SORT handles commit_inputs request inside kdamond thread,
reading the module parameters. If the user updates the module
parameters while the kdamond thread is reading those, races can happen.
To avoid this, the commit_inputs parameter shows whether it is still in
the progress, assuming users wouldn't update parameters in the middle of
the work. Some users might ignore that. Add a warning about the
behavior.
The issue was discovered in [1] by sashiko.
Link: https://lore.kernel.org/20260329153052.46657-3-sj@kernel.org
Link: https://lore.kernel.org/20260319161620.189392-2-objecting@objecting.org [1]
Fixes: 6acfcd0d7524 ("Docs/admin-guide/damon: add a document for DAMON_LRU_SORT")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.0.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | Documentation/admin-guide/mm/damon/lru_sort.rst | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/admin-guide/mm/damon/lru_sort.rst b/Documentation/admin-guide/mm/damon/lru_sort.rst index a7dea7c75a9b..14cc6b2db897 100644 --- a/Documentation/admin-guide/mm/damon/lru_sort.rst +++ b/Documentation/admin-guide/mm/damon/lru_sort.rst @@ -79,6 +79,10 @@ of parametrs except ``enabled`` again. Once the re-reading is done, this parameter is set as ``N``. If invalid parameters are found while the re-reading, DAMON_LRU_SORT will be disabled. +Once ``Y`` is written to this parameter, the user must not write to any +parameters until reading ``commit_inputs`` again returns ``N``. If users +violate this rule, the kernel may exhibit undefined behavior. + active_mem_bp ------------- |