DAMON sysfs interface is using a single global repeat mode damon_call_control variable for refresh_ms handling, for all DAMON contexts. As a result, when there are more than one context, the single global damon_call_control is unexpectedly over-written (corrupted). Particularly the ->link field is overwritten by the multiple contexts and this can cause a user hangup, and/or a kernel crash. Fix it by using dynamically allocated damon_call_control object per DAMON context. Fixes: d809a7c64ba8 ("mm/damon/sysfs: implement refresh_ms file internal work") # v6.17-rc1 Reported-by: Yunjeong Mun Closes: https://lore.kernel.org/20250904011738.930-1-yunjeong.mun@sk.com Signed-off-by: SeongJae Park --- mm/damon/sysfs.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c index 6625fb718195..fe4e73d0ebbb 100644 --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1569,14 +1569,10 @@ static int damon_sysfs_repeat_call_fn(void *data) return 0; } -static struct damon_call_control damon_sysfs_repeat_call_control = { - .fn = damon_sysfs_repeat_call_fn, - .repeat = true, -}; - static int damon_sysfs_turn_damon_on(struct damon_sysfs_kdamond *kdamond) { struct damon_ctx *ctx; + struct damon_call_control *repeat_call_control; int err; if (damon_sysfs_kdamond_running(kdamond)) @@ -1589,18 +1585,29 @@ static int damon_sysfs_turn_damon_on(struct damon_sysfs_kdamond *kdamond) damon_destroy_ctx(kdamond->damon_ctx); kdamond->damon_ctx = NULL; + repeat_call_control = kmalloc(sizeof(*repeat_call_control), + GFP_KERNEL); + if (!repeat_call_control) + return -ENOMEM; + ctx = damon_sysfs_build_ctx(kdamond->contexts->contexts_arr[0]); - if (IS_ERR(ctx)) + if (IS_ERR(ctx)) { + kfree(repeat_call_control); return PTR_ERR(ctx); + } err = damon_start(&ctx, 1, false); if (err) { + kfree(repeat_call_control); damon_destroy_ctx(ctx); return err; } kdamond->damon_ctx = ctx; - damon_sysfs_repeat_call_control.data = kdamond; - damon_call(ctx, &damon_sysfs_repeat_call_control); + repeat_call_control->fn = damon_sysfs_repeat_call_fn; + repeat_call_control->data = kdamond; + repeat_call_control->repeat = true; + repeat_call_control->dealloc_on_cancel = true; + damon_call(ctx, repeat_call_control); return err; } -- 2.39.5