6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: SeongJae Park <sj@xxxxxxxxxx> commit 76b7069bcc89dec33f03eb08abee165d0306b754 upstream. 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@xxxxxxxxxx Fixes: f1d13cacabe1 ("mm/damon/sysfs: implement DAMOS tried regions update command") Signed-off-by: SeongJae Park <sj@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [6.2.x] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/damon/sysfs.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1202,6 +1202,8 @@ 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; @@ -1209,10 +1211,12 @@ static void damon_sysfs_before_terminate /* damon_sysfs_schemes_update_regions_stop() might not yet called */ kdamond = damon_sysfs_cmd_request.kdamond; - if (kdamond && damon_sysfs_cmd_request.cmd == + if (kdamond && (damon_sysfs_cmd_request.cmd == DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_REGIONS && + damon_sysfs_schemes_regions_updating) && ctx == kdamond->damon_ctx) { damon_sysfs_schemes_update_regions_stop(ctx); + damon_sysfs_schemes_regions_updating = false; mutex_unlock(&damon_sysfs_lock); } @@ -1331,7 +1335,6 @@ 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; int err = 0; /* avoid deadlock due to concurrent state_store('off') */
