linux-kernel - [BUG] mm: truncate: a possible sleep-in-atomic-context bug in truncate_exceptional_pvec

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Message-ID: <f863cf8d-615f-c622-812a-a6370efe757b@gmail.com>
Date:   Mon, 13 Aug 2018 11:10:23 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     akpm@...ux-foundation.org, jack@...e.cz,
        mgorman@...hsingularity.net, ak@...ux.intel.com,
        mawilcox@...rosoft.com, viro@...iv.linux.org.uk,
        mawilcox@...rosoft.com, ross.zwisler@...ux.intel.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: [BUG] mm: truncate: a possible sleep-in-atomic-context bug in
 truncate_exceptional_pvec_entries()

The kernel may sleep with holding a spinlock.

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

[FUNC] schedule
fs/dax.c, 259: schedule in get_unlocked_mapping_entry
fs/dax.c, 450: get_unlocked_mapping_entry in __dax_invalidate_mapping_entry
fs/dax.c, 471: __dax_invalidate_mapping_entry in dax_delete_mapping_entry
mm/truncate.c, 97: dax_delete_mapping_entry in 
truncate_exceptional_pvec_entries
mm/truncate.c, 82: spin_lock_irq in truncate_exceptional_pvec_entries

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