Re: [PATCH v3 1/2] mm/damon/lru_sort: validate min_region_size to be power of 2

[Liew Rui Yan <aethernet65535@gmail.com>]

Hi SeongJae,

On Fri,  3 Apr 2026 09:19:06 -0700 SeongJae Park <sj@kernel.org> wrote:

> As Quanmin also asked, clarifying the unexpected termination would be nice.

I will clarify "unexpected termination" in v4's commit message:

    "Unexpectedly" here means the kdamond terminates without the user
    requesting it (e.g., not by wrtting "N" to 'enabled').

> I remember I suggested adding stable@, but only if you think it deserve.  I'm
> now not very sure if this deserves Cc-ing stable@.  As I mentioned before,

I think this deserves Cc stable@ because:
- The issue can be triggered by accidental user misconfiguration
- It causes kdamond termination and hard to recover/restart. Once
  triggered, kdamond remains in an unusable state, and I have not found
  a way to recover/restart it through the sysfs interface without a
  system reboot.
- The fix is small and low-risk
- It improves user experience on stable kernels

But I'm open to dropping it if you think otherwise.

> there are multiple patches to review in parallel (you are also having such
> multiple patches in the queue).  Please don't expect I will follow full
> contexts especially when a single person posting multiple patches in parallel
> every day or two, and bear in mind with me.
> 
> Sorry about the limited bandwidth from my side.  You could also simply slow
> down your pace, though.

I will try to adjust my pace. I've also noticed that the quality of my
recent replies/patches hasn't been ideal, and I will try to be less
rushed in the future. Thank you for your understanding and suggestion.

> For stable@ Cc-ing patches, more clearly describing the user impact would be
> nice, and helpful for judging if it deserves that.  Could you please elaborate?

I will add a "User Impact" section in v4's commit message:

    User Impact
    ===========
    Currently, if a user commit an invalid 'addr_unit', kdamond may
    terminate abruptly. Once terminated, it cannot be easily restarted
    via sysfs, pontentially requiring a system reboot to restore DAMON
    functionality. This patch prevent such termination by validating
    parameters (addr_unit and min_region_sz) early.

Best regards,
Rui Yan