linux-kernel - Re: [PATCHv2 2/2] zram: clear IDLE flag in mark

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Message-ID: <Zx_QblcMMLznXd4P@google.com>
Date: Mon, 28 Oct 2024 13:57:02 -0400
From: Brian Geffon <bgeffon@...gle.com>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Minchan Kim <minchan@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 2/2] zram: clear IDLE flag in mark_idle()

On Tue, Oct 29, 2024 at 12:36:15AM +0900, Sergey Senozhatsky wrote:
> If entry does not fulfill current mark_idle() parameters, e.g.
> cutoff time, then we should clear its ZRAM_IDLE from previous
> mark_idle() invocations.
> 
> Consider the following case:
> - mark_idle() cutoff time 8h
> - mark_idle() cutoff time 4h
> - writeback() idle - will writeback entries with cutoff time 8h,
>   while it should only pick entries with cutoff time 4h
> 
> The bug was reported by Shin Kawamura.
Reported-by: Shin Kawamura <kawasin@...gle.com>

> 
> Fixes: 755804d16965 ("zram: introduce an aged idle interface")
> Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
Acked-by: Brian Geffon <bgeffon@...gle.com>

> ---
>  drivers/block/zram/zram_drv.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index a16dbffcdca3..cee49bb0126d 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -410,6 +410,8 @@ static void mark_idle(struct zram *zram, ktime_t cutoff)
>  #endif
>  		if (is_idle)
>  			zram_set_flag(zram, index, ZRAM_IDLE);
> +		else
> +			zram_clear_flag(zram, index, ZRAM_IDLE);
>  		zram_slot_unlock(zram, index);
>  	}
>  }
> -- 
> 2.47.0.163.g1226f6d8fa-goog
>