linux-kernel - [BUG] fs: nfs: callback_proc: a possible sleep-in-atomic-context bug in nfs4_callback

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Message-ID: <d2edd56f-782e-737b-b6a8-ca0b5be94f00@gmail.com>
Date:   Mon, 13 Aug 2018 11:43:04 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     trond.myklebust@...merspace.com, anna.schumaker@...app.com
Cc:     linux-nfs@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [BUG] fs: nfs: callback_proc: a possible sleep-in-atomic-context bug
 in nfs4_callback_sequence()

The kernel may sleep with holding a spinlock.

The function call paths (from bottom to top) in Linux-4.16 are:

[FUNC] schedule_timeout
fs/nfs/nfs4session.c, 223: schedule_timeout in nfs4_slot_wait_on_seqid
fs/nfs/callback_proc.c, 466: nfs4_slot_wait_on_seqid in 
referring_call_exists
fs/nfs/callback_proc.c, 544: referring_call_exists in nfs4_callback_sequence
fs/nfs/callback_proc.c, 504: spin_lock in nfs4_callback_sequence

I do not find a good way to fix, so I only report.
This is found by my static analysis tool (DSAC).


Thanks,
Jia-Ju Bai