The patch titled Subject: mm/damon/sysfs: check DAMOS regions update progress from before_terminate() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-damon-sysfs-check-damos-regions-update-progress-from-before_terminate.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: SeongJae Park sj@kernel.org Subject: mm/damon/sysfs: check DAMOS regions update progress from before_terminate() Date: Sat, 7 Oct 2023 20:04:32 +0000

DAMON_SYSFS can receive DAMOS tried regions update request while kdamond is already out of the main loop and before_terminate callback (damon_sysfs_before_terminate() in this case) is not yet called. And damon_sysfs_handle_cmd() can further be finished before the callback is invoked. Then, damon_sysfs_before_terminate() unlocks damon_sysfs_lock, which is not locked by anyone. This happens because the callback function assumes damon_sysfs_cmd_request_callback() should be called before it. Check if the assumption was true before doing the unlock, to avoid this problem.

Link: https://lkml.kernel.org/r/20231007200432.3110-1-sj@kernel.org Fixes: f1d13cacabe1 ("mm/damon/sysfs: implement DAMOS tried regions update command") Signed-off-by: SeongJae Park sj@kernel.org Cc: stable@vger.kernel.org [6.2.x] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/damon/sysfs.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/mm/damon/sysfs.c~mm-damon-sysfs-check-damos-regions-update-progress-from-before_terminate +++ a/mm/damon/sysfs.c @@ -1208,6 +1208,8 @@ static int damon_sysfs_set_targets(struc return 0; }

+static bool damon_sysfs_schemes_regions_updating; + static void damon_sysfs_before_terminate(struct damon_ctx *ctx) { struct damon_target *t, *next; @@ -1219,8 +1221,10 @@ static void damon_sysfs_before_terminate cmd = damon_sysfs_cmd_request.cmd; if (kdamond && ctx == kdamond->damon_ctx && (cmd == DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_REGIONS || - cmd == DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_BYTES)) { + cmd == DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_BYTES) && + damon_sysfs_schemes_regions_updating) { damon_sysfs_schemes_update_regions_stop(ctx); + damon_sysfs_schemes_regions_updating = false; mutex_unlock(&damon_sysfs_lock); }

@@ -1340,7 +1344,6 @@ static int damon_sysfs_commit_input(stru static int damon_sysfs_cmd_request_callback(struct damon_ctx *c) { struct damon_sysfs_kdamond *kdamond; - static bool damon_sysfs_schemes_regions_updating; bool total_bytes_only = false; int err = 0;

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Patches currently in -mm which might be from sj@kernel.org are

mm-damon-sysfs-check-damos-regions-update-progress-from-before_terminate.patch