From patchwork Sat Oct 2 23:51:13 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nagendra Tomar X-Patchwork-Id: 66589 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id DAE5BB6F0D for ; Sun, 3 Oct 2010 10:51:38 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752037Ab0JBXvP (ORCPT ); Sat, 2 Oct 2010 19:51:15 -0400 Received: from web53703.mail.re2.yahoo.com ([206.190.37.24]:42022 "HELO web53703.mail.re2.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752017Ab0JBXvO convert rfc822-to-8bit (ORCPT ); Sat, 2 Oct 2010 19:51:14 -0400 Received: (qmail 74933 invoked by uid 60001); 2 Oct 2010 23:51:13 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1286063473; bh=cc6gTa902NP2oJ5nkajWMHgp+ns4SWUQ/h0gs/or228=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding; b=l69ITPmbCftMy7v1NGjepJX2iDerOevGw7Ie0Ih3AjoBD8aokpCsjrNHhMTInGhl1LMG7sMC6PNbOCLwlajtyMu0katbEGBFe3wE3IUstc5WSxoL6SQJlVIhCImtYG5QH4RE6U4aZEcTx43EhHALPNL3+hiQx3jkU+u8Z7XhLX4= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding; b=SY6FVDIXrwVteJpBwO0pHDkELebw+U+zc6sAsi3P0P3tSoLS/0Ux12QQ/RKrqyAD6G4M4dU3mNXA4IAYHn/2u5JHeNzDdWHxfoW5irPslc8VzGeMq6Xc119dnuQAVu/BVdfcyU+27Qt19nnGS63n/MfnKoFvEMUNK8SvkgXGZTQ=; Message-ID: <380276.68827.qm@web53703.mail.re2.yahoo.com> X-YMail-OSG: PF17JHMVM1nLxkRt2d_8qDj6_zGPKH2gholZ8bGjTnskSi4 EVjH3686LEhyxqZXVSAfSWfa4GMjGOIWFgOTHXPpaq7ZC091btyejKQe3ov6 idPKw3fapVwn4xl8_rRxvlZIO8Fw8XEnjLA3lzLuNM1LoziTZXVcxzNM49Rk mshSYrJ_0Og.wdie.EPFn9jdyS6dSClfztxy4dHZE4hmF5x4E7XBOUebsBdy d570IQ5rf1f7eve8.EsWOEmB4JHx7sbbDLsIthfSL36vAw7FNgy6ml4Q7.8_ AayXMs5HxfPtDPs04_ND.lYUkqAzw2E6QUNonFkI9u25Fnnxx5hZCuhU- Received: from [69.147.103.86] by web53703.mail.re2.yahoo.com via HTTP; Sat, 02 Oct 2010 16:51:13 PDT X-Mailer: YahooMailClassic/11.4.9 YahooMailWebService/0.8.105.279950 Date: Sat, 2 Oct 2010 16:51:13 -0700 (PDT) From: Nagendra Tomar Subject: [PATCH 2/2] net: Fix the condition passed to sk_wait_event() To: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, davem@davemloft.net MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch fixes the condition (3rd arg) passed to sk_wait_event() in sk_stream_wait_memory(). The incorrect check in sk_stream_wait_memory() causes the following soft lockup in tcp_sendmsg() when the global tcp memory pool has exhausted. >>> snip <<< localhost kernel: BUG: soft lockup - CPU#3 stuck for 11s! [sshd:6429] localhost kernel: CPU 3: localhost kernel: RIP: 0010:[sk_stream_wait_memory+0xcd/0x200] [sk_stream_wait_memory+0xcd/0x200] sk_stream_wait_memory+0xcd/0x200 localhost kernel: localhost kernel: Call Trace: localhost kernel: [sk_stream_wait_memory+0x1b1/0x200] sk_stream_wait_memory+0x1b1/0x200 localhost kernel: [] autoremove_wake_function+0x0/0x40 localhost kernel: [ipv6:tcp_sendmsg+0x6e6/0xe90] tcp_sendmsg+0x6e6/0xce0 localhost kernel: [sock_aio_write+0x126/0x140] sock_aio_write+0x126/0x140 localhost kernel: [xfs:do_sync_write+0xf1/0x130] do_sync_write+0xf1/0x130 localhost kernel: [] autoremove_wake_function+0x0/0x40 localhost kernel: [hrtimer_start+0xe3/0x170] hrtimer_start+0xe3/0x170 localhost kernel: [vfs_write+0x185/0x190] vfs_write+0x185/0x190 localhost kernel: [sys_write+0x50/0x90] sys_write+0x50/0x90 localhost kernel: [system_call+0x7e/0x83] system_call+0x7e/0x83 >>> snip <<< What is happening is, that the sk_wait_event() condition passed from sk_stream_wait_memory() evaluates to true for the case of tcp global memory exhaustion. This is because both sk_stream_memory_free() and vm_wait are true which causes sk_wait_event() to *not* call schedule_timeout(). Hence sk_stream_wait_memory() returns immediately to the caller w/o sleeping. This causes the caller to again try allocation, which again fails and again calls sk_stream_wait_memory(), and so on. Signed-off-by: Nagendra Singh Tomar --- --- -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- linux-2.6.35.7/net/core/stream.c.orig 2010-03-24 09:31:00.000000000 +0530 +++ linux-2.6.35.7/net/core/stream.c 2010-03-24 09:31:08.000000000 +0530 @@ -143,10 +143,9 @@ int sk_stream_wait_memory(struct sock *s set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); sk->sk_write_pending++; - sk_wait_event(sk, ¤t_timeo, !sk->sk_err && - !(sk->sk_shutdown & SEND_SHUTDOWN) && - sk_stream_memory_free(sk) && - vm_wait); + sk_wait_event(sk, ¤t_timeo, sk->sk_err || + (sk->sk_shutdown & SEND_SHUTDOWN) || + (sk_stream_memory_free(sk) && !vm_wait)); sk->sk_write_pending--; if (vm_wait) {