[BUG REPORT] potential deadlock in inode evicting under the inode lru traversing context on ext4 and ubifs

[Zhihao Cheng]

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.
>