[Devel] [PATCH rh7 1/3] net: core: use __GFP_NORETRY for high order allocations

[Anatoly Stepanov]

This is a backport of upstream (vanilla) change.

Original commit: ed98df3361f059db42786c830ea96e2d18b8d4db

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:
 [<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
 [<ffffffff80295fa0>] tcp_sendmsg+0x560/0xee0
 [<ffffffff802a5037>] inet_sendmsg+0x67/0x100
 [<ffffffff80283c9c>] __sock_sendmsg_nosec+0x6c/0x90
 [<ffffffff80283e85>] sock_sendmsg+0xc5/0xf0
 [<ffffffff802847b6>] __sys_sendmsg+0x136/0x430
 [<ffffffff80284ec8>] sys_sendmsg+0x88/0x110
 [<ffffffff80711472>] system_call_fastpath+0x16/0x1b
Out of Memory: Kill process 2856 (bash) score 9999 or sacrifice child

Signed-off-by: Eric Dumazet <edumazet at google.com>
Acked-by: David Rientjes <rientjes at google.com>
Acked-by: "Eric W. Biederman" <ebiederm at xmission.com>
Signed-off-by: David S. Miller <davem at davemloft.net>

Signed-off-by: Andrew Perepechko <panda at cloudlinux.com>
---
 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 5124311..a94e1d0 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1817,7 +1817,9 @@ 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;
@@ -1879,7 +1881,7 @@ bool sk_page_frag_refill(struct sock *sk, struct page_frag *pfrag)
 		gfp_t gfp = sk->sk_allocation;
 
 		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;
-- 
1.8.3.1