Commit eb52da3f authored May 03, 2017 by Michal Hocko Committed by Linus Torvalds May 03, 2017

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.

[akpm@linux-foundation.org: coding-style fixes]
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 81378da6

fs/jbd2/journal.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -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>
		@@ -205,6 +206,14 @@ static int kjournald2(void *arg)
		journal->j_task = current;
		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.
		*/