Re: [PATCH v5 2/2] mm/damon/reclaim: validate min_region_size to be power of 2

[SeongJae Park <sj@kernel.org>]

On Fri,  1 May 2026 09:37:50 +0800 Liew Rui Yan <aethernet65535@gmail.com> wrote:

> Problem
> =======
> When a user sets an invalid 'addr_unit' (e.g., 3) via DAMON_RECLAIM,
> 'min_region_sz' becomes a non-power-of-2 value. While damon_commit_ctx()
> correctly detects this and returns -EINVAL, it sets the
> 'maybe_corrupted' flag during this process.
> 
> This flag causes the running kdamond to terminate. While the termination
> is a safety measure, it is suboptimal in this case because the error is
> just a simple invalid input from the user, which shouldn't neccessitate
> stopping the kdamond.
> 
> Reproduction
> ============
> 1. Enable DAMON_RECLAIM
> 2. Set addr_unit=3
> 3. Commit inputs via 'commit_inputs'
> 4. Observe kdamond termination
> 
> Solution
> ========
> Add an early validation in damon_reclaim_apply_parameters() to check
> 'min_region_sz' before any state change occurs. If it is non-power-of-2,
> return -EINVAL immediately, preventing 'maybe_corrupted' from being set.

Looks good to me.

> 
> Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

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