[6.1.176 regression] damon_reclaim.enabled broken

[6.1.176 regression] damon_reclaim.enabled broken

[Yikai Zhao]

Hello kernel maintainers,

(Newbie here)

I found out that in 6.1.177, booting with cmdline
`damon_reclaim.enabled=Y` does not work anymore,
`/sys/module/damon_reclaim/parameters/enabled` is still `N` after
booting.

6.1.175 works OK. Apparently it's introduced in commit 2f54908fae21.


Thanks,
Yikai

Re: [6.1.176 regression] damon_reclaim.enabled broken

[Liew Rui Yan]

Hi Yikai,

Thank you for reporting this issue :>

I just investigated the problem and found the root cause. It looks like
a typo in damon_reclaim_timer_fn(), where '!=' was used instead of '=='
(unlike damon_lru_sort), which caused the delayed work to return early
and fail to enable during early boot.

Comparison
==========

    /* DAMON_RECLAIM */
    static void damon_reclaim_timer_fn(struct work_struct *work)
    {
        bool now_enabled;

        now_enabled = enabled;
        if (damon_reclaim_enabled() != now_enabled)
            return;
        damon_reclaim_turn(now_enabled);
    }

    /* DAMON_LRU_SORT */
    static void damon_lru_sort_timer_fn(struct work_struct *work)
    {
        bool now_enabled;

        now_enabled = enabled;
        if (damon_lru_sort_enabled() == now_enabled)
            return;
        damon_lru_sort_turn(now_enabled);
    }

This appears to affect only version .176 and .177 (introduced by
2f54908fae211).

I will send out the fix patch as soon as possible!

Best regards,
Rui Yan

Re: [6.1.176 regression] damon_reclaim.enabled broken

[SJ Park]

On Mon, 20 Jul 2026 17:28:40 +0800 Liew Rui Yan <aethernet65535@gmail.com> wrote:

> Hi Yikai,
> 
> Thank you for reporting this issue :>

Thank you for the reporting, Yikai!

> 
> I just investigated the problem and found the root cause. It looks like
> a typo in damon_reclaim_timer_fn(), where '!=' was used instead of '=='
> (unlike damon_lru_sort), which caused the delayed work to return early
> and fail to enable during early boot.
> 
> Comparison
> ==========
> 
>     /* DAMON_RECLAIM */
>     static void damon_reclaim_timer_fn(struct work_struct *work)
>     {
>         bool now_enabled;
> 
>         now_enabled = enabled;
>         if (damon_reclaim_enabled() != now_enabled)
>             return;
>         damon_reclaim_turn(now_enabled);
>     }
> 
>     /* DAMON_LRU_SORT */
>     static void damon_lru_sort_timer_fn(struct work_struct *work)
>     {
>         bool now_enabled;
> 
>         now_enabled = enabled;
>         if (damon_lru_sort_enabled() == now_enabled)
>             return;
>         damon_lru_sort_turn(now_enabled);
>     }

Thank you for investigating this, Liew!

> 
> This appears to affect only version .176 and .177 (introduced by
> 2f54908fae211).

Correct.  Apparently this was due to a mistake in porting.

> 
> I will send out the fix patch as soon as possible!

I found you sent [1] it already.  Let's further discuss on the thread.

[1] https://lore.kernel.org/20260720094708.243937-1-aethernet65535@gmail.com


Thanks,
SJ

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