>> On Thu, 2014-01-02 at 16:56 -0800, Eric Dumazet wrote:
>>
>> Hmm... it looks like I missed __GFP_NORETRY
>>
>>
>>
>> diff --git a/net/core/sock.c b/net/core/sock.c
>> index 5393b4b719d7..5f42a4d70cb2 100644
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -1872,7 +1872,7 @@ bool skb_page_frag_refill(unsigned int sz, struct
>> page_frag *pfrag, gfp_t prio)
>> gfp_t gfp = prio;
>>
>> if (order)
>> - gfp |= __GFP_COMP | __GFP_NOWARN;
>> + gfp |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY;
>> pfrag->page = alloc_pages(gfp, order);
>> if (likely(pfrag->page)) {
>> pfrag->offset = 0;
>>
>>
>>
There is another patch needed (looks like good stable fixes):
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 06e72d3..d42d48c 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -378,7 +378,7 @@ refill:
gfp_t gfp = gfp_mask;
if (order)
- gfp |= __GFP_COMP | __GFP_NOWARN;
+ gfp |= __GFP_COMP | __GFP_NOWARN |
__GFP_NORETRY;
nc->frag.page = alloc_pages(gfp, order);
if (likely(nc->frag.page))
break;
This reduces the really pathological compact/reclaim behavior but
doesn't fix it. Actually it still really quite bad because the whole
thing loops until it gets to order-0 so it's effectively trying the
allocation 4 times anyway. I typically see non-zero order allocations
very rarely without these two pieces of code. I hotpatched a running
system to get results from this quickly. Even setting the max order to
order-1 I still see bad behavior. If anything this behavior should be
conditional until this is ironed out.
Performance data: http://pastebin.ubuntu.com/6687527/
-Debabrata
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