Received-SPF: pass (google.com: domain of linux-kernel+bounces-27303-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
From: Christian Brauner <brauner@kernel.org>
To: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Christian Brauner <brauner@kernel.org>,
	willy@infradead.org,
	viro@zeniv.linux.org.uk,
	jack@suse.cz,
	linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	akpm@linux-foundation.org
Subject: Re: [PATCH] fs: improve dump_mapping() robustness
Date: Tue, 16 Jan 2024 12:16:35 +0100
Message-ID: <20240116-privat-zeitplan-21db23926f45@brauner>
In-Reply-To:  <937ab1f87328516821d39be672b6bc18861d9d3e.1705391420.git.baolin.wang@linux.alibaba.com>
References:  <937ab1f87328516821d39be672b6bc18861d9d3e.1705391420.git.baolin.wang@linux.alibaba.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit

On Tue, 16 Jan 2024 15:53:35 +0800, Baolin Wang wrote:
> We met a kernel crash issue when running stress-ng testing, and the
> system crashes when printing the dentry name in dump_mapping().
> 
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> pc : dentry_name+0xd8/0x224
> lr : pointer+0x22c/0x370
> sp : ffff800025f134c0
> ......
> Call trace:
>   dentry_name+0xd8/0x224
>   pointer+0x22c/0x370
>   vsnprintf+0x1ec/0x730
>   vscnprintf+0x2c/0x60
>   vprintk_store+0x70/0x234
>   vprintk_emit+0xe0/0x24c
>   vprintk_default+0x3c/0x44
>   vprintk_func+0x84/0x2d0
>   printk+0x64/0x88
>   __dump_page+0x52c/0x530
>   dump_page+0x14/0x20
>   set_migratetype_isolate+0x110/0x224
>   start_isolate_page_range+0xc4/0x20c
>   offline_pages+0x124/0x474
>   memory_block_offline+0x44/0xf4
>   memory_subsys_offline+0x3c/0x70
>   device_offline+0xf0/0x120
>   ......
> 
> [...]

Seems fine for debugging purposes. Let me know if this needs to go through
somewhere else.

---

Applied to the vfs.misc branch of the vfs/vfs.git tree.
Patches in the vfs.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.misc

[1/1] fs: improve dump_mapping() robustness
      https://git.kernel.org/vfs/vfs/c/30a1b9d12728