linux-kernel - [BUG] fs/aio: A possible sleep-in-atomic bug in aio

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Date:   Sat, 7 Oct 2017 09:36:48 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     bcrl@...ck.org, Al Viro <viro@...iv.linux.org.uk>
Cc:     linux-aio@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [BUG] fs/aio: A possible sleep-in-atomic bug in aio_migratepage

According to fs/aio.c, cond_resched is called under a spinlock,
and the function call path is:
aio_migratepage (acquire the spinlock)
   migrate_page_copy
     copy_huge_page
       __copy_gigantic_page
         cond_resched
           might_sleep

This bug is found by my static analysis tool and my code review.
A possible fix is to remove cond_resched in __copy_gigantic_page.


Thanks,
Jia-Ju Bai