Re: [PATCH v2] mm/damon: validate min_region_size to be power of 2

SeongJae Park
2026-04-02T14:03:20Z

On Thu, 2 Apr 2026 13:37:56 +0800 Liew Rui Yan <aethernet65535@gmail.com> wrote:

> Problem
> =======
> damon_commit_ctx() checks if 'min_region_sz' is a power of 2. But if it
> is not, kdamond will terminate unexpectedly due to the user's invalid
> input.

Could you please further elaborate visible user impact of the problem and
reproduction steps if available?

>
> Solution
> ========
> Add the same check to damon_{lru_sort, reclaim}_apply_parameters(), but
> return -EINVAL immediately. This is to prevent user's invalid input
> causing kdamond to terminate unexpectedly.
>
> This patch is a follow-up to the discussion in [1], where we agreed that
> the validation should be done on min_region_sz rather than addr_unit.
>
> [1] https://lore.kernel.org/20260330233343.4083-1-sj@kernel.org
>

Should we add Fixes: and Cc: stable@ ?

If we should Cc: stable@, and if the changes for DAMON_RECLAIM and
DAMON_LRU_SORT deserve different Fixes:, I think this patch is better to be
split into two patches, one for DAMON_RECLAIM, and the other for
DAMON_LRU_SORT.

> Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
> ---
> Changes from v1:
> - Fix memory leak issue.
> - Link to v1: https://lore.kernel.org/20260331073231.30060-1-aethernet65535@gmail.com

Seems you forgot the patch [1] before renaming of the subject.

[...]

The code changes look good to me.

[1] https://lore.kernel.org/20260327062627.66426-1-aethernet65535@gmail.com

Thanks,
SJ