From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: David Carlier <devnexen@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] zram: fix slot lock bit position on big-endian 64-bit
Date: Tue, 11 Aug 2026 11:06:41 +0900 [thread overview]
Message-ID: <anqDmZKiVfyNB5FL@google.com> (raw)
In-Reply-To: <20260810202241.2436603-1-devnexen@gmail.com>
On (26/08/10 21:22), David Carlier wrote:
> The slot lock is a bit operation on the whole __lock word, which
> flags and ac_time alias as two u32s. On little-endian the lock bit
> lands in the position ZRAM_ENTRY_LOCK reserves in flags, so the
> aliasing works out. On 64-bit big-endian it lands in ac_time
> instead: with ZRAM_TRACK_ENTRY_ACTIME enabled, storing the access
> time from mark_slot_accessed() or slot_free() wipes out the held
> lock bit, letting another CPU take the same slot lock; an access
> time value with that bit set makes the slot look locked forever.
>
> Shift the lock bit into the flags half of the word on big-endian
> 64-bit.
>
> Fixes: 2e8ff2f51dde ("zram: use u32 for entry ac_time tracking")
> Cc: stable@vger.kernel.org
> Signed-off-by: David Carlier <devnexen@gmail.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
prev parent reply other threads:[~2026-08-11 2:06 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-10 20:22 [PATCH] zram: fix slot lock bit position on big-endian 64-bit David Carlier
2026-08-11 2:06 ` Sergey Senozhatsky [this message]
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