+ jbd2-make-the-whole-kjournald2-kthread-nofs-safe.patch added to -mm tree

+ jbd2-make-the-whole-kjournald2-kthread-nofs-safe.patch added to -mm tree

[akpm]

The patch titled
     Subject: jbd2: make the whole kjournald2 kthread NOFS safe
has been added to the -mm tree.  Its filename is
     jbd2-make-the-whole-kjournald2-kthread-nofs-safe.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/jbd2-make-the-whole-kjournald2-kthread-nofs-safe.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/jbd2-make-the-whole-kjournald2-kthread-nofs-safe.patch

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------------------------------------------------------
From: Michal Hocko <mhocko@suse.com>
Subject: jbd2: make the whole kjournald2 kthread NOFS safe

kjournald2 is central to the transaction commit processing.  As such any
potential allocation from this kernel thread has to be GFP_NOFS.  Make
sure to mark the whole kernel thread GFP_NOFS by the memalloc_nofs_save.

Link: http://lkml.kernel.org/r/20170306131408.9828-8-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/jbd2/journal.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff -puN fs/jbd2/journal.c~jbd2-make-the-whole-kjournald2-kthread-nofs-safe fs/jbd2/journal.c
--- a/fs/jbd2/journal.c~jbd2-make-the-whole-kjournald2-kthread-nofs-safe
+++ a/fs/jbd2/journal.c
@@ -43,6 +43,7 @@
 #include <linux/backing-dev.h>
 #include <linux/bitops.h>
 #include <linux/ratelimit.h>
+#include <linux/sched/mm.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/jbd2.h>
@@ -206,6 +207,13 @@ static int kjournald2(void *arg)
 	wake_up(&journal->j_wait_done_commit);
 
 	/*
+	 * Make sure that no allocations from this kernel thread will ever recurse
+	 * to the fs layer because we are responsible for the transaction commit
+	 * and any fs involvement might get stuck waiting for the trasn. commit.
+	 */
+	memalloc_nofs_save();
+
+	/*
 	 * And now, wait forever for commit wakeup events.
 	 */
 	write_lock(&journal->j_state_lock);
_

Patches currently in -mm which might be from mhocko@suse.com are

lockdep-allow-to-disable-reclaim-lockup-detection.patch
xfs-abstract-pf_fstrans-to-pf_memalloc_nofs.patch
mm-introduce-memalloc_nofs_saverestore-api.patch
xfs-use-memalloc_nofs_saverestore-instead-of-memalloc_noio.patch
jbd2-mark-the-transaction-context-with-the-scope-gfp_nofs-context.patch
jbd2-make-the-whole-kjournald2-kthread-nofs-safe.patch