Re: [PATCH v1] mm/damon/sysfs: propagate damon_call() error in turn_damon_on

[SJ Park <sj@kernel.org>]

On Tue, 15 Sep 2026 17:39:28 +0800 Xuewen Wang <wangxuewen@kylinos.cn> wrote:

> damon_sysfs_turn_damon_on() ignored the return value of damon_call()
> for the repeat call control registration and always returned the stale
> result of damon_start() (0 at that point). When damon_call() fails,
> e.g., the kdamond is already exiting, the user still gets success from
> the state file write while monitoring is not actually on.
> 
> Save and return the damon_call() result instead. No rollback of
> damon_start() is needed since a failed damon_call() guarantees the
> context is stopped.

Nice catch, thank you for fixing this!
> 
> Signed-off-by: Xuewen Wang <wangxuewen@kylinos.cn>

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

This patch is applied to damon/next [1] tree.  If this patch is not added to
mm.git in short term (~1 week?), I will ask mm.git maintainer (Andrew Morton)
to pick this.  So, no action from your side is needed for now.  If it seems I
also forgot doing that or you cannot wait for my action, please feel free to
directly ask that to Andrew.

[1] https://origin.kernel.org/doc/html/latest/mm/damon/maintainer-profile.html#scm-trees


Thanks,
SJ

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