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mm/damon/sysfs: use dynamically allocated repeat mode damon_call_control

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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.

Link: https://lkml.kernel.org/r/20250908201513.60802-3-sj@kernel.org
Link: https://lore.kernel.org/20250904011738.930-1-yunjeong.mun@sk.com [1]
Link: https://lore.kernel.org/20250905035411.39501-1-sj@kernel.org [2]
Fixes: d809a7c64b ("mm/damon/sysfs: implement refresh_ms file internal work")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Yunjeong Mun <yunjeong.mun@sk.com>
Closes: https://lore.kernel.org/20250904011738.930-1-yunjeong.mun@sk.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
SeongJae Park 2025-09-08 13:15:13 -07:00 committed by Andrew Morton
parent e6a0deb6fa
commit 04a06b139e
1 changed files with 15 additions and 8 deletions
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23
mm/damon/sysfs.c
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@ -1534,14 +1534,10 @@ 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))
@ -1554,18 +1550,29 @@ 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;
}