lkml.org 
[lkml]   [2013]   [Oct]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH 3.5 29/64] fs: buffer: move allocation failure loop into the allocator
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 <hannes@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 <azurit@pobox.sk>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@suse.cz>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Luis Henriques <luis.henriques@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
>


\
 
 \ /
  Last update: 2013-10-31 16:01    [W:0.216 / U:1.704 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site