lkml.org 
[lkml]   [2011]   [Oct]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
SubjectRe: [PATCH] mm: avoid livelock on !__GFP_FS allocations
From
On Tue, Oct 25, 2011 at 11:24 PM, David Rientjes <rientjes@google.com> wrote:
> On Tue, 25 Oct 2011, Colin Cross wrote:
>
>> > Or, rather, when pm_restrict_gfp_mask() clears __GFP_IO and __GFP_FS that
>> > it also has the same behavior as __GFP_NORETRY in should_alloc_retry() by
>> > setting a variable in file scope.
>> >
>>
>> Why do you prefer that over adding a gfp_required_mask?
>>
>
> Because it avoids an unnecessary OR in the page and slab allocator
> fastpaths which are red hot :)
>

Makes sense. What about this? Official patch to follow.

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fef8dc3..59cd4ff 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1786,6 +1786,13 @@ should_alloc_retry(gfp_t gfp_mask, unsigned int order,
return 0;

/*
+ * If PM has disabled I/O, OOM is disabled and reclaim is unlikely
+ * to make any progress. To prevent a livelock, don't retry.
+ */
+ if (!(gfp_allowed_mask & __GFP_FS))
+ return 0;
+
+ /*
* In this implementation, order <= PAGE_ALLOC_COSTLY_ORDER
* means __GFP_NOFAIL, but that may not be true in other
* implementations.

\
 
 \ /
  Last update: 2011-10-26 08:29    [W:2.580 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site