Subject: sk_page_frag_refill OOM killing spree

From: Florian Westphal <[email-masked]>
Date: Tue, 21 May 2013 14:28:45 +0200

Hi Eric,

seems like sk_page_frag_refill() can cause oom-killer invocation:

postgres invoked oom-killer: gfp_mask=0x42d0, order=3, oom_score_adj=0
Pid: 10551, comm: postgres Tainted: G           O 3.8.6-5.g613ca40-smp #1
Call Trace:
 [<c106dbd5>] ? dump_header+0x60/0x191
 [<c1133d3a>] ? ___ratelimit+0xb2/0xc4
 [<c106dfd3>] ? oom_kill_process+0x61/0x2d1
 [<c1030042>] ? has_capability_noaudit+0x1c/0x23
 [<c106df0f>] ? oom_badness+0x8c/0xef
 [<c106e446>] ? out_of_memory+0x203/0x247
 [<c107128a>] ? __alloc_pages_nodemask+0x42b/0x4c3
 [<c11fa66a>] ? sk_page_frag_refill+0x6a/0xd2
 [<c1233548>] ? tcp_sendmsg+0x3e8/0x7c6
 [<c124f34b>] ? inet_sendmsg+0x6b/0x75
 [<c11f74d8>] ? sock_sendmsg+0x8d/0xa6
 [<c11f7b83>] ? sys_sendto+0x105/0x130
 [<c1025927>] ? __kunmap_atomic+0x62/0x8a
 [<c1025940>] ? __kunmap_atomic+0x7b/0x8a
 [<c1073d78>] ? __lru_cache_add+0x18/0x47
 [<c10812f9>] ? handle_pte_fault+0x745/0x751
 [<c1025a2d>] ? kmap_atomic_prot+0xd3/0xf1
 [<c10817da>] ? handle_mm_fault+0x112/0x121
 [<c11f7be5>] ? sys_send+0x37/0x3b

The system is busy, so, order-3 alloc failure doesn't strike me as odd.

There are no allocation failures with order != 3.

Sometimes this can happen in very short sucession, i.e.
and oom-killer did end up zapping 30 processes or so.

My question is, should sk_page_frag_refill use __GFP_NORETRY, at least
for order 3 requests?