+ xfs-warn-if-direct-reclaim-tries-to-writeback-pages.patch added to -mm tree

+ xfs-warn-if-direct-reclaim-tries-to-writeback-pages.patch added to -mm tree

[akpm]

The patch titled
     xfs: warn if direct reclaim tries to writeback pages
has been added to the -mm tree.  Its filename is
     xfs-warn-if-direct-reclaim-tries-to-writeback-pages.patch

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------------------------------------------------------
Subject: xfs: warn if direct reclaim tries to writeback pages
From: Mel Gorman <mgorman@suse.de>

Direct reclaim should never writeback pages.  For now, handle the
situation and warn about it.  Ultimately, this will be a BUG_ON.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alex Elder <aelder@sgi.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <>
---

 fs/xfs/xfs_aops.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff -puN fs/xfs/xfs_aops.c~xfs-warn-if-direct-reclaim-tries-to-writeback-pages fs/xfs/xfs_aops.c
--- a/fs/xfs/xfs_aops.c~xfs-warn-if-direct-reclaim-tries-to-writeback-pages
+++ a/fs/xfs/xfs_aops.c
@@ -925,11 +925,11 @@ xfs_vm_writepage(
 	 * random callers for direct reclaim or memcg reclaim.  We explicitly
 	 * allow reclaim from kswapd as the stack usage there is relatively low.
 	 *
-	 * This should really be done by the core VM, but until that happens
-	 * filesystems like XFS, btrfs and ext4 have to take care of this
-	 * by themselves.
+	 * This should never happen except in the case of a VM regression so
+	 * warn about it.
 	 */
-	if ((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == PF_MEMALLOC)
+	if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
+			PF_MEMALLOC))
 		goto redirty;
 
 	/*
_

Patches currently in -mm which might be from mgorman@suse.de are

mm-compaction-trivial-clean-up-in-acct_isolated.patch
mm-change-isolate-mode-from-define-to-bitwise-type.patch
mm-compaction-make-isolate_lru_page-filter-aware.patch
mm-zone_reclaim-make-isolate_lru_page-filter-aware.patch
mm-migration-clean-up-unmap_and_move.patch
mm-page-writebackc-make-determine_dirtyable_memory-static-again.patch
mm-vmscan-do-not-writeback-filesystem-pages-in-direct-reclaim.patch
mm-vmscan-remove-dead-code-related-to-lumpy-reclaim-waiting-on-pages-under-writeback.patch
xfs-warn-if-direct-reclaim-tries-to-writeback-pages.patch
ext4-warn-if-direct-reclaim-tries-to-writeback-pages.patch
mm-vmscan-do-not-writeback-filesystem-pages-in-kswapd-except-in-high-priority.patch
mm-vmscan-throttle-reclaim-if-encountering-too-many-dirty-pages-under-writeback.patch
mm-vmscan-immediately-reclaim-end-of-lru-dirty-pages-when-writeback-completes.patch
hugepages-fix-race-between-hugetlbfs-umount-and-quota-update-checkpatch-fixes.patch