From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx141.postini.com [74.125.245.141]) by kanga.kvack.org (Postfix) with SMTP id E89BD8D0001 for ; Thu, 27 Dec 2012 21:16:44 -0500 (EST) Date: Fri, 28 Dec 2012 03:16:38 +0100 From: Zlatko Calusic MIME-Version: 1.0 References: <50D24AF3.1050809@iskon.hr> <20121220111208.GD10819@suse.de> <20121220125802.23e9b22d.akpm@linux-foundation.org> <50D601C9.9060803@iskon.hr> <50D71166.6030608@iskon.hr> <50DB129E.7010000@iskon.hr> In-Reply-To: <50DB129E.7010000@iskon.hr> Message-ID: <50DD0106.7040001@iskon.hr> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: [PATCH] mm: fix null pointer dereference in wait_iff_congested() Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Mel Gorman Cc: Linus Torvalds , Hugh Dickins , linux-mm , Linux Kernel Mailing List , Zhouping Liu , Sedat Dilek From: Zlatko Calusic The unintended consequence of commit 4ae0a48b is that wait_iff_congested() can now be called with NULL struct zone* producing kernel oops like this: BUG: unable to handle kernel NULL pointer dereference IP: [] wait_iff_congested+0x59/0x140 This trivial patch fixes it. Reported-by: Zhouping Liu Reported-and-tested-by: Sedat Dilek Cc: Andrew Morton Cc: Mel Gorman Cc: Hugh Dickins Signed-off-by: Zlatko Calusic --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 02bcfa3..e55ce55 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2782,7 +2782,7 @@ loop_again: if (total_scanned && (sc.priority < DEF_PRIORITY - 2)) { if (has_under_min_watermark_zone) count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); - else + else if (unbalanced_zone) wait_iff_congested(unbalanced_zone, BLK_RW_ASYNC, HZ/10); } -- 1.8.1.rc3 -- Zlatko -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753053Ab2L1CQr (ORCPT ); Thu, 27 Dec 2012 21:16:47 -0500 Received: from mxout2.iskon.hr ([213.191.128.81]:46601 "EHLO mxout2.iskon.hr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752758Ab2L1CQp (ORCPT ); Thu, 27 Dec 2012 21:16:45 -0500 X-Remote-IP: 213.191.128.133 Date: Fri, 28 Dec 2012 03:16:38 +0100 From: Zlatko Calusic Organization: Iskon Internet d.d. User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Icedove/17.0 MIME-Version: 1.0 To: Andrew Morton , Mel Gorman CC: Linus Torvalds , Hugh Dickins , linux-mm , Linux Kernel Mailing List , Zhouping Liu , Sedat Dilek References: <50D24AF3.1050809@iskon.hr> <20121220111208.GD10819@suse.de> <20121220125802.23e9b22d.akpm@linux-foundation.org> <50D601C9.9060803@iskon.hr> <50D71166.6030608@iskon.hr> <50DB129E.7010000@iskon.hr> In-Reply-To: <50DB129E.7010000@iskon.hr> Message-ID: <50DD0106.7040001@iskon.hr> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: [PATCH] mm: fix null pointer dereference in wait_iff_congested() X-Anti-Virus: Kaspersky Anti-Virus for Linux Mail Server 5.6.45/RELEASE, bases: 20121228 #8901209, check: 20121228 clean X-SpamTest-Envelope-From: zlatko.calusic@iskon.hr X-SpamTest-Group-ID: 00000000 X-SpamTest-Info: Profiles 40800 [Dec 28 2012] X-SpamTest-Method: none X-SpamTest-Rate: 0 X-SpamTest-SPF: none X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0284], KAS30/Release Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zlatko Calusic The unintended consequence of commit 4ae0a48b is that wait_iff_congested() can now be called with NULL struct zone* producing kernel oops like this: BUG: unable to handle kernel NULL pointer dereference IP: [] wait_iff_congested+0x59/0x140 This trivial patch fixes it. Reported-by: Zhouping Liu Reported-and-tested-by: Sedat Dilek Cc: Andrew Morton Cc: Mel Gorman Cc: Hugh Dickins Signed-off-by: Zlatko Calusic --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 02bcfa3..e55ce55 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2782,7 +2782,7 @@ loop_again: if (total_scanned && (sc.priority < DEF_PRIORITY - 2)) { if (has_under_min_watermark_zone) count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); - else + else if (unbalanced_zone) wait_iff_congested(unbalanced_zone, BLK_RW_ASYNC, HZ/10); } -- 1.8.1.rc3 -- Zlatko