[PATCH 1/1] LogFS: Deadlock in logfs_get_wblocks, hold and wait on super->s_write_mutex

[Prasad Joshi]

do_logfs_journal_wl_pass() should use GFP_NOFS for memory allocation
GC code calls btree_insert32 with GFP_KERNEL while holding a mutex
super->s_write_mutex. The same mutex is used in
address_space_operations->writepage(). Call to writepage() could be triggered
as a result of memory allocation in btree_insert32, causing a deadlock.


Signed-off-by: Prasad Joshi <prasadjoshi124@xxxxxxxxx>
---
diff --git a/fs/logfs/journal.c b/fs/logfs/journal.c
index f46ee8b..9da2970 100644
--- a/fs/logfs/journal.c
+++ b/fs/logfs/journal.c
@@ -828,7 +828,7 @@ void do_logfs_journal_wl_pass(struct super_block *sb)
         super->s_journal_seg[i] = segno;
         super->s_journal_ec[i] = ec;
         logfs_set_segment_reserved(sb, segno);
-        err = btree_insert32(head, segno, (void *)1, GFP_KERNEL);
+        err = btree_insert32(head, segno, (void *)1, GFP_NOFS);
         BUG_ON(err); /* mempool should prevent this */
         err = logfs_erase_segment(sb, segno, 1);
         BUG_ON(err); /* FIXME: remount-ro would be nicer */


---------- Forwarded message ----------
From: <bugzilla-daemon@xxxxxxxxxxxxxxxxxxx>
Date: Tue, Nov 16, 2010 at 3:28 PM
Subject: [Bug 20342] [LogFS] [2.6.36-rc7] Deadlock in
logfs_get_wblocks, hold and wait on same lock super->s_write_mutex
To: prasadjoshi124@xxxxxxxxx


https://bugzilla.kernel.org/show_bug.cgi?id=20342


Florian Mickler <florian@xxxxxxxxxxx> changed:

          What    |Removed                     |Added
----------------------------------------------------------------------------
                CC|                            |florian@xxxxxxxxxxx




--- Comment #2 from Florian Mickler <florian@xxxxxxxxxxx>  2010-11-16
15:27:59 ---
Please submit this patch on lkml and the logfs mailinglist for review. The
logfs maintainers seem to not be aware of the bugzilla.

( Documentation/SubmittingPatches )

--
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/