linux-kernel - Re: [PATCH] md/bitmap: fix GPF in write

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Message-Id: <ad63a8bf-410f-4b91-aa89-3963dadf87af@fnnas.com>
Date: Mon, 26 Jan 2026 13:33:43 +0800
From: "Yu Kuai" <yukuai@...as.com>
To: "Jack Wang" <jinpu.wang@...os.com>, <song@...nel.org>, 
	<linux-raid@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Cc: <stable@...r.kernel.org>, <yukuai@...as.com>
Subject: Re: [PATCH] md/bitmap: fix GPF in write_page caused by resize race

在 2026/1/20 18:24, Jack Wang 写道:

> A General Protection Fault occurs in write_page() during array resize:
> RIP: 0010:write_page+0x22b/0x3c0 [md_mod]
>
> This is a use-after-free race between bitmap_daemon_work() and
> __bitmap_resize(). The daemon iterates over `bitmap->storage.filemap`
> without locking, while the resize path frees that storage via
> md_bitmap_file_unmap(). `quiesce()` does not stop the md thread,
> allowing concurrent access to freed pages.
>
> Fix by holding `mddev->bitmap_info.mutex` during the bitmap update.
>
> Closes:https://lore.kernel.org/linux-raid/CAMGffE=Mbfp=7xD_hYxXk1PAaCZNSEAVeQGKGy7YF9f2S4=NEA@mail.gmail.com/T/#u
> Cc:stable@...r.kernel.org
> Signed-off-by: Jack Wang<jinpu.wang@...os.com>
> ---
>   drivers/md/md-bitmap.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)

Applied with a fixtag:

Fixes: d60b479d177a ("md/bitmap: add bitmap_resize function to allow 
bitmap resizing.")

-- 
Thansk,
Kuai