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Date: Thu, 06 Feb 2014 13:34:04 -0800 From: Joe Perches <joe@...ches.com> To: David Rientjes <rientjes@...gle.com> Cc: Eric Dumazet <eric.dumazet@...il.com>, David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] net: use __GFP_NORETRY for high order allocations On Thu, 2014-02-06 at 13:03 -0800, David Rientjes wrote: > On Thu, 6 Feb 2014, Joe Perches wrote: > > > On Thu, 2014-02-06 at 10:42 -0800, Eric Dumazet wrote: > > > sock_alloc_send_pskb() & sk_page_frag_refill() > > > have a loop trying high order allocations to prepare > > > skb with low number of fragments as this increases performance. > > > > > > Problem is that under memory pressure/fragmentation, this can > > > trigger OOM while the intent was only to try the high order > > > allocations, then fallback to order-0 allocations. > > [] > > > Call Trace: > > > [<ffffffff8043766c>] dump_header+0xe1/0x23e > > > [<ffffffff80437a02>] oom_kill_process+0x6a/0x323 > > > [<ffffffff80438443>] out_of_memory+0x4b3/0x50d > > > [<ffffffff8043a4a6>] __alloc_pages_may_oom+0xa2/0xc7 > > > [<ffffffff80236f42>] __alloc_pages_nodemask+0x1002/0x17f0 > > > [<ffffffff8024bd23>] alloc_pages_current+0x103/0x2b0 > > > [<ffffffff8028567f>] sk_page_frag_refill+0x8f/0x160 > > [] > > > diff --git a/net/core/sock.c b/net/core/sock.c > > [] > > > @@ -1775,7 +1775,9 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len, > > > while (order) { > > > if (npages >= 1 << order) { > > > page = alloc_pages(sk->sk_allocation | > > > - __GFP_COMP | __GFP_NOWARN, > > > + __GFP_COMP | > > > + __GFP_NOWARN | > > > + __GFP_NORETRY, > > > order); > > > if (page) > > > goto fill_page; > > > @@ -1845,7 +1847,7 @@ 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; > > > > Perhaps add __GFP_THISNODE too ? > > > > How does __GFP_THISNODE have anything to do with avoiding oom killing due > to high-order fragmentation? I don't think it does. > If they absolutely require local memory to > currnet's cpu node then that would make sense, I presumed THISNODE would be used only with NORETRY > but the fallback still > allocates order-0 memory remotely and with __GFP_THISNODE on this attempt > we wouldn't even attempt remote reclaim. any other alloc attempt could work on other cpus. It was just a thought, ignore it if it's a dumb thought. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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