Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755749Ab0KYAdv (ORCPT ); Wed, 24 Nov 2010 19:33:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:4861 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753884Ab0KYAdu (ORCPT ); Wed, 24 Nov 2010 19:33:50 -0500 Date: Wed, 24 Nov 2010 19:33:39 -0500 From: Dave Jones To: Linux Kernel Cc: linux-mm@vger.kernel.org, Andrew Morton Subject: rcu_read_lock/unlock protect find_task_by_vpid call in migrate_pages Message-ID: <20101125003339.GB31301@redhat.com> Mail-Followup-To: Dave Jones , Linux Kernel , linux-mm@vger.kernel.org, Andrew Morton MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1876 Lines: 52 =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- kernel/pid.c:419 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 1 lock held by scrashme/11079: #0: (tasklist_lock){.?.?..}, at: [] sys_migrate_pages+0xd6/0x29d stack backtrace: Pid: 11079, comm: scrashme Not tainted 2.6.37-rc3+ #2 Call Trace: [] lockdep_rcu_dereference+0x9d/0xa5 [] find_task_by_pid_ns+0x44/0x5d [] find_task_by_vpid+0x22/0x24 [] sys_migrate_pages+0xe3/0x29d [] ? trace_hardirqs_off_caller+0xa3/0x10b [] ? retint_swapgs+0x13/0x1b [] ? trace_hardirqs_on_caller+0x13f/0x172 [] ? trace_hardirqs_on_thunk+0x3a/0x3f [] system_call_fastpath+0x16/0x1b Signed-off-by: Dave Jones diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 4a57f13..2f0f55b 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1308,6 +1308,7 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode, /* Find the mm_struct */ read_lock(&tasklist_lock); + rcu_read_lock(); task = pid ? find_task_by_vpid(pid) : current; if (!task) { read_unlock(&tasklist_lock); @@ -1315,6 +1316,7 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode, goto out; } mm = get_task_mm(task); + rcu_read_unlock(); read_unlock(&tasklist_lock); err = -EINVAL; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/