On Thu, 2013-10-31 at 10:01 -0400, Johannes Weiner wrote: > This fix was tagged as a reminder for a bigger series, please don't > apply for now. Thanks Johannes -- I've dropped this one from the 3.8-stable queue. -Kamal > On Tue, Oct 29, 2013 at 11:04:40AM -0700, Kamal Mostafa wrote: > > 3.8.13.12 -stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Johannes Weiner <hannes@xxxxxxxxxxx> > > > > 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 <azurit@xxxxxxxx> > > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> > > Cc: Michal Hocko <mhocko@xxxxxxx> > > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx> > > --- > > 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 7a75c3e..be83882 100644 > > --- a/fs/buffer.c > > +++ b/fs/buffer.c > > @@ -965,9 +965,19 @@ 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 6b7ff19..b150e66f 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -2614,6 +2614,8 @@ done: > > return 0; > > nomem: > > *ptr = NULL; > > + if (gfp_mask & __GFP_NOFAIL) > > + return 0; > > return -ENOMEM; > > bypass: > > *ptr = root_mem_cgroup; > > -- > > 1.8.1.2 > > >
Attachment:
signature.asc
Description: This is a digitally signed message part