Re: [RFC PATCH v1.3 4/4] mm/damon/sysfs: set next refresh jiffies per sysfs context

[sashiko-bot@kernel.org]

> When 'refresh_ms' is set, DAMON sysfs interface periodically updates
> auto-tuned parameters and DAMOS stats.  The timestamp for the next
> refresh is initialized when a DAMON context starts, and updated in its
> damon_call() callback function.  That is, each DAMON context updates it.
> However, the timestamp is a global variable that is shared with all the
> contexts.  When there are multiple DAMON contexts having different
> refresh_ms, the update frequency will be changed, depending on the order
> of the contexts.  When there are multiple kdamonds, it will be even more
> chaotic.  Fix the problem by having the timestamp per each context.
> 
> The user impact is not very critical.  It does not leak, corrupt or
> crash.  The update will not be faster or slower than the lowest and
> largest refresh_ms values of the contexts, respectively.  The user can
> also manually ask the updates on demand using kdamond state commands.
> That said, clearly this is a bug and can easily be reproduced.
> 
> Fixes: 9fd7bb5083d1 ("mm/damon/sysfs: change next_update_jiffies to a global variable")
> Cc: <stable@vger.kernel.org> # 6.18.x
> Signed-off-by: SJ Park <sj@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260828183649.71192-1-sj@kernel.org?part=4