linux-kernel - [BUG] fs/super: a possible sleep-in-atomic bug in put

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Date:   Fri, 6 Oct 2017 16:59:18 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     viro@...iv.linux.org.uk, torbjorn.lindh@...ta.se,
        rgooch@...f.csiro.au
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [BUG] fs/super: a possible sleep-in-atomic bug in put_super

According to fs/super.c, the kernel may sleep under a spinlock.
The function call path is:
put_super (acquire the spinlock)
   __put_super
     destroy_super
       list_lru_destroy
         list_lru_unregister
           mutex_lock --> may sleep
         memcg_get_cache_ids
           down_read --> may sleep

This bug is found by my static analysis tool and my code review.

Thanks,
Jia-Ju Bai