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Message-ID: <YrbZEIxC62XjVBwL@B-P7TQMD6M-0146.local>
Date: Sat, 25 Jun 2022 17:44:48 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: Even <cheny_wen@....com>
Cc: xiang@...nel.org, chao@...nel.org, linux-erofs@...ts.ozlabs.org,
linux-kernel@...r.kernel.org, Even <chenyuwen1@...zu.com>
Subject: Re: [PATCH] erofs: Wake up all waiters after z_erofs_lzma_head ready.
Hi,
On Sat, Jun 25, 2022 at 04:57:38PM +0800, Even wrote:
> From: Even <chenyuwen1@...zu.com>
>
> When the user mounts the erofs second times, the decompression thread
> may hung. The problem happens due to a sequence of steps like the
> following:
>
> 1) Task A called z_erofs_load_lzma_config which obtain all of the node
> from the z_erofs_lzma_head.
>
> 2) At this time, task B called the z_erofs_lzma_decompress and wanted to
> get a node. But the z_erofs_lzma_head was empty, the Task B had to
> sleep.
>
> 3) Task A release nodes and push nodes into the z_erofs_lzma_head. But
> task B was still sleeping.
>
> One example report when the hung happens:
> task:kworker/u3:1 state:D stack:14384 pid: 86 ppid: 2 flags:0x00004000
> Workqueue: erofs_unzipd z_erofs_decompressqueue_work
> Call Trace:
> <TASK>
> __schedule+0x281/0x760
> schedule+0x49/0xb0
> z_erofs_lzma_decompress+0x4bc/0x580
> ? cpu_core_flags+0x10/0x10
> z_erofs_decompress_pcluster+0x49b/0xba0
> ? __update_load_avg_se+0x2b0/0x330
> ? __update_load_avg_se+0x2b0/0x330
> ? update_load_avg+0x5f/0x690
> ? update_load_avg+0x5f/0x690
> ? set_next_entity+0xbd/0x110
> ? _raw_spin_unlock+0xd/0x20
> z_erofs_decompress_queue.isra.0+0x2e/0x50
> z_erofs_decompressqueue_work+0x30/0x60
> process_one_work+0x1d3/0x3a0
> worker_thread+0x45/0x3a0
> ? process_one_work+0x3a0/0x3a0
> kthread+0xe2/0x110
> ? kthread_complete_and_exit+0x20/0x20
> ret_from_fork+0x22/0x30
> </TASK>
>
> Signed-off-by: Even <chenyuwen1@...zu.com>
Thanks a lot for catching this!
The patch itself looks good, but could you use your real name to sign
off the patch and resend a version? see,
https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html#developer-s-certificate-of-origin-1-1
Otherwise it looks good to me,
Reviewed-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
Thanks,
Gao Xiang
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