From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH] net: use __GFP_NORETRY for high order allocations Date: Thu, 06 Feb 2014 18:03:23 -0800 Message-ID: <87txcbisr8.fsf@xmission.com> References: <1391712162.10160.8.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain Cc: David Miller , netdev , David Rientjes , "linux-kernel\@vger.kernel.org" To: Eric Dumazet Return-path: In-Reply-To: <1391712162.10160.8.camel@edumazet-glaptop2.roam.corp.google.com> (Eric Dumazet's message of "Thu, 06 Feb 2014 10:42:42 -0800") Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Eric Dumazet writes: > From: Eric Dumazet > > 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. > > We had various reports from unexpected regressions. > > According to David, setting __GFP_NORETRY should be fine, > as the asynchronous compaction is still enabled, and this > will prevent OOM from kicking as in : > > CFSClientEventm invoked oom-killer: gfp_mask=0x42d0, order=3, oom_adj=0, > oom_score_adj=0, oom_score_badness=2 (enabled),memcg_scoring=disabled > CFSClientEventm > > Call Trace: > [] dump_header+0xe1/0x23e > [] oom_kill_process+0x6a/0x323 > [] out_of_memory+0x4b3/0x50d > [] __alloc_pages_may_oom+0xa2/0xc7 > [] __alloc_pages_nodemask+0x1002/0x17f0 > [] alloc_pages_current+0x103/0x2b0 > [] sk_page_frag_refill+0x8f/0x160 > [] tcp_sendmsg+0x560/0xee0 > [] inet_sendmsg+0x67/0x100 > [] __sock_sendmsg_nosec+0x6c/0x90 > [] sock_sendmsg+0xc5/0xf0 > [] __sys_sendmsg+0x136/0x430 > [] sys_sendmsg+0x88/0x110 > [] system_call_fastpath+0x16/0x1b > Out of Memory: Kill process 2856 (bash) score 9999 or sacrifice child > > Signed-off-by: Eric Dumazet > Acked-by: David Rientjes Acked-by: "Eric W. Biederman" I have seen similiar order 3 allocation failures as well and reached the same conclusion that __GFP_NORETRY was the solution. Eric > --- > net/core/sock.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/net/core/sock.c b/net/core/sock.c > index 0c127dcdf6a8..5b6a9431b017 100644 > --- 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; > pfrag->page = alloc_pages(gfp, order); > if (likely(pfrag->page)) { > pfrag->offset = 0; > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/