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Message-ID: <68bae3be-9a98-83b1-a378-b7c7c12f74c7@linaro.org>
Date:   Thu, 15 Dec 2022 15:07:46 +0200
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Subject: Re: BUG: unable to handle kernel paging request in
 z_erofs_decompress_queue
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From:   Tudor Ambarus <tudor.ambarus@linaro.org>
To:     linux-erofs@lists.ozlabs.org, xiang@kernel.org, chao@kernel.org,
        huyue2@coolpad.com, jefflexu@linux.alibaba.com
Cc:     joneslee@google.com, linux-kernel@vger.kernel.org
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On 15.12.2022 14:58, Tudor Ambarus wrote:
> Hi, Gao, Chao, Yue, Jeffle, all,
> 
> Syzbot reported a bug at [1] that is reproducible in upstream kernel
> since
>    commit 47e4937a4a7c ("erofs: move erofs out of staging")
> 
> and up to (inclusively)
>    commit 2bfab9c0edac ("erofs: record the longest decompressed size in 
> this round")
> 
> The first commit that makes this bug go away is:
>    commit 267f2492c8f7 ("erofs: introduce multi-reference pclusters 
> (fully-referenced)")
> Although, this commit looks like new support and not like an explicit
> bug fix.
> 
> I'd like to fix the lts kernels. I'm happy to try any suggestions or do
> some tests. Please let me know if the bug rings a bell.
> 

There's something else that may help. I enabled CONFIG_EROFS_FS_DEBUG
while at
   commit 2bfab9c0edac ("erofs: record the longest decompressed size in 
this round")
and I got the following: https://termbin.com/4bm8

Cheers,
ta

> [1] 
> https://syzkaller.appspot.com/bug?id=a9b56d324d0de9233ad80633826fac76836d792a