This is part of a bigger series and was tagged for stable as a reminder only. Please don't apply for now.
On Mon, Oct 28, 2013 at 02:47:48PM +0000, Luis Henriques wrote: > 3.5.7.24 -stable review patch. If anyone has any objections, please let me > know. > > ------------------ > > From: Johannes Weiner <han...@cmpxchg.org> > > commit 84235de394d9775bfaa7fa9762a59d91fef0c1fc upstream. > > Buffer allocation has a very crude indefinite loop around waking the > flusher threads and performing global NOFS direct reclaim because it can > not handle allocation failures. > > The most immediate problem with this is that the allocation may fail due > to a memory cgroup limit, where flushers + direct reclaim might not make > any progress towards resolving the situation at all. Because unlike the > global case, a memory cgroup may not have any cache at all, only > anonymous pages but no swap. This situation will lead to a reclaim > livelock with insane IO from waking the flushers and thrashing unrelated > filesystem cache in a tight loop. > > Use __GFP_NOFAIL allocations for buffers for now. This makes sure that > any looping happens in the page allocator, which knows how to > orchestrate kswapd, direct reclaim, and the flushers sensibly. It also > allows memory cgroups to detect allocations that can't handle failure > and will allow them to ultimately bypass the limit if reclaim can not > make progress. > > Reported-by: azurIt <azu...@pobox.sk> > Signed-off-by: Johannes Weiner <han...@cmpxchg.org> > Cc: Michal Hocko <mho...@suse.cz> > Signed-off-by: Andrew Morton <a...@linux-foundation.org> > Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> > Signed-off-by: Luis Henriques <luis.henriq...@canonical.com> > --- > fs/buffer.c | 14 ++++++++++++-- > mm/memcontrol.c | 2 ++ > 2 files changed, 14 insertions(+), 2 deletions(-) > > diff --git a/fs/buffer.c b/fs/buffer.c > index 2c78739..2675e5a 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -957,9 +957,19 @@ grow_dev_page(struct block_device *bdev, sector_t block, > struct buffer_head *bh; > sector_t end_block; > int ret = 0; /* Will call free_more_memory() */ > + gfp_t gfp_mask; > > - page = find_or_create_page(inode->i_mapping, index, > - (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); > + gfp_mask = mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS; > + gfp_mask |= __GFP_MOVABLE; > + /* > + * XXX: __getblk_slow() can not really deal with failure and > + * will endlessly loop on improvised global reclaim. Prefer > + * looping in the allocator rather than here, at least that > + * code knows what it's doing. > + */ > + gfp_mask |= __GFP_NOFAIL; > + > + page = find_or_create_page(inode->i_mapping, index, gfp_mask); > if (!page) > return ret; > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 226b63e..953bf3c 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2405,6 +2405,8 @@ done: > return 0; > nomem: > *ptr = NULL; > + if (gfp_mask & __GFP_NOFAIL) > + return 0; > return -ENOMEM; > bypass: > *ptr = root_mem_cgroup; > -- > 1.8.3.2 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
