From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964882Ab1DNR6J (ORCPT ); Thu, 14 Apr 2011 13:58:09 -0400 Received: from mail.windriver.com ([147.11.1.11]:41736 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964855Ab1DNR6D (ORCPT ); Thu, 14 Apr 2011 13:58:03 -0400 From: Paul Gortmaker To: stable@kernel.org, linux-kernel@vger.kernel.org Cc: stable-review@kernel.org, Eric Dumazet , "David S. Miller" , Paul Gortmaker Subject: [34-longterm 142/209] af_unix: limit unix_tot_inflight Date: Thu, 14 Apr 2011 13:55:00 -0400 Message-Id: <1302803767-9715-29-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.4.4 In-Reply-To: <1302803767-9715-1-git-send-email-paul.gortmaker@windriver.com> References: <1302803039-9400-1-git-send-email-paul.gortmaker@windriver.com> <1302803767-9715-1-git-send-email-paul.gortmaker@windriver.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet ===================================================================== | This is a commit scheduled for the next v2.6.34 longterm release. | | If you see a problem with using this for longterm, please comment.| ===================================================================== commit 9915672d41273f5b77f1b3c29b391ffb7732b84b upstream Vegard Nossum found a unix socket OOM was possible, posting an exploit program. My analysis is we can eat all LOWMEM memory before unix_gc() being called from unix_release_sock(). Moreover, the thread blocked in unix_gc() can consume huge amount of time to perform cleanup because of huge working set. One way to handle this is to have a sensible limit on unix_tot_inflight, tested from wait_for_unix_gc() and to force a call to unix_gc() if this limit is hit. This solves the OOM and also reduce overall latencies, and should not slowdown normal workloads. Reported-by: Vegard Nossum Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Paul Gortmaker --- net/unix/garbage.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/net/unix/garbage.c b/net/unix/garbage.c index 14c22c3..ef5aa55 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -268,9 +268,16 @@ static void inc_inflight_move_tail(struct unix_sock *u) } static bool gc_in_progress = false; +#define UNIX_INFLIGHT_TRIGGER_GC 16000 void wait_for_unix_gc(void) { + /* + * If number of inflight sockets is insane, + * force a garbage collect right now. + */ + if (unix_tot_inflight > UNIX_INFLIGHT_TRIGGER_GC && !gc_in_progress) + unix_gc(); wait_event(unix_gc_wait, gc_in_progress == false); } -- 1.7.4.4