From: Jan Kara <jack@suse.cz>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-fsdevel@vger.kernel.org, Barret Rhoden <brho@google.com>,
Jan Kara <jack@suse.cz>,
linux-nvdimm@lists.01.org
Subject: [PATCH] dax: Fix deadlock in dax_lock_mapping_entry()
Date: Thu, 27 Sep 2018 13:23:32 +0200 [thread overview]
Message-ID: <20180927112332.3649-1-jack@suse.cz> (raw)
When dax_lock_mapping_entry() has to sleep to obtain entry lock, it will
fail to unlock mapping->i_pages spinlock and thus immediately deadlock
against itself when retrying to grab the entry lock again. Fix the
problem by unlocking mapping->i_pages before retrying.
Fixes: c2a7d2a115525d3501d38e23d24875a79a07e15e
Reported-by: Barret Rhoden <brho@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/dax.c | 1 +
1 file changed, 1 insertion(+)
Dan, can you please get this merged? Otherwise dax_lock_mapping_entry()
deadlocks as soon as there's any contention.
diff --git a/fs/dax.c b/fs/dax.c
index b68ce484e1be..4becbf168b7f 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -447,6 +447,7 @@ bool dax_lock_mapping_entry(struct page *page)
xa_unlock_irq(&mapping->i_pages);
break;
} else if (IS_ERR(entry)) {
+ xa_unlock_irq(&mapping->i_pages);
WARN_ON_ONCE(PTR_ERR(entry) != -EAGAIN);
continue;
}
--
2.16.4
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next reply other threads:[~2018-09-27 11:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-27 11:23 Jan Kara [this message]
2018-09-27 13:28 ` Matthew Wilcox
2018-09-27 13:41 ` Jan Kara
2018-09-27 18:22 ` Dan Williams
2018-10-04 16:27 ` Jan Kara
2018-10-05 1:57 ` Dan Williams
2018-10-05 2:52 ` Matthew Wilcox
2018-10-05 4:01 ` Dan Williams
2018-10-05 4:28 ` Dan Williams
2018-10-05 9:54 ` Jan Kara
2018-10-06 18:04 ` Dan Williams
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