On Thu, Oct 31, 2013 at 10:00:08AM -0400, Johannes Weiner wrote: > This is part of a bigger series and was tagged for stable as a > reminder only. Please don't apply for now.
Grrr... I need to start cleaning my email inbox before doing a release. I just saw the discussion in stable@. I'll do an emergency release reverting this patch. Thanks for catching this. Cheers, -- Luis > > 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 stable" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/
