The patch below does not apply to the 6.5-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.5.y git checkout FETCH_HEAD git cherry-pick -x 76b7069bcc89dec33f03eb08abee165d0306b754 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023102716-prudishly-reggae-1b29@gregkh' --subject-prefix 'PATCH 6.5.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 76b7069bcc89dec33f03eb08abee165d0306b754 Mon Sep 17 00:00:00 2001 From: SeongJae Park sj@kernel.org Date: Sat, 7 Oct 2023 20:04:32 +0000 Subject: [PATCH] mm/damon/sysfs: check DAMOS regions update progress from before_terminate()

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

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c index b86ba7b0a921..f60e56150feb 100644 --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1208,6 +1208,8 @@ static int damon_sysfs_set_targets(struct damon_ctx *ctx, 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(struct damon_ctx *ctx) 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(struct damon_sysfs_kdamond *kdamond) 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;