linux-kernel - Re: [BUG REPORT] potential deadlock in inode evicting under the inode lru traversing context on ext4 and ubifs

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Message-ID: <e67d289d-fd5e-cb38-4e2f-a2bbb8419a97@huaweicloud.com>
Date: Mon, 5 Aug 2024 09:29:14 +0800
From: Zhihao Cheng <chengzhihao@...weicloud.com>
To: linux-fsdevel <linux-fsdevel@...r.kernel.org>,
 linux-ext4@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
 Ted Tso <tytso@....edu>, Jan Kara <jack@...e.cz>,
 Christoph Hellwig <hch@...radead.org>,
 linux-mtd <linux-mtd@...ts.infradead.org>,
 Richard Weinberger <richard@....at>, "zhangyi (F)" <yi.zhang@...wei.com>,
 yangerkun <yangerkun@...wei.com>, "wangzhaolong (A)"
 <wangzhaolong1@...wei.com>, mjguzik@...il.com,
 "rydercoding@...mail.com >> Ryder Wang" <rydercoding@...mail.com>
Subject: Re: [BUG REPORT] potential deadlock in inode evicting under the inode
 lru traversing context on ext4 and ubifs

Hi, based on the ideas from Jan and Mateusz, I sent a fix patch, see 
https://lore.kernel.org/linux-fsdevel/20240805013446.814357-1-chengzhihao@huaweicloud.com/T/#u

在 2024/7/12 14:27, Zhihao Cheng 写道:
> Hi. Recently, we found a deadlock in inode recliaiming process caused by 
> circular dependence between file inode and file's xattr inode.
> 
> Problem description
> ===================
> 
> The inode reclaiming process(See function prune_icache_sb) collects all 
> reclaimable inodes and mark them with I_FREEING flag at first, at that 
> time, other processes will be stuck if they try getting these inodes(See 
> function find_inode_fast), then the reclaiming process destroy the 
> inodes by function dispose_list().
> Some filesystems(eg. ext4 with ea_inode feature, ubifs with xattr) may 
> do inode lookup in the inode evicting callback function, if the inode 
> lookup is operated under the inode lru traversing context, deadlock 
> problems may happen.
>