nvdimm.lists.linux.dev archive mirror
 help / color / mirror / Atom feed
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

_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

             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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180927112332.3649-1-jack@suse.cz \
    --to=jack@suse.cz \
    --cc=brho@google.com \
    --cc=dan.j.williams@intel.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-nvdimm@lists.01.org \
    --subject='Re: [PATCH] dax: Fix deadlock in dax_lock_mapping_entry()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).