Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753402AbaKHDtN (ORCPT ); Fri, 7 Nov 2014 22:49:13 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:29928 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753287AbaKHDtM (ORCPT ); Fri, 7 Nov 2014 22:49:12 -0500 Message-ID: <545D928B.2070508@oracle.com> Date: Fri, 07 Nov 2014 22:48:27 -0500 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Kirill Tkhai , linux-kernel@vger.kernel.org CC: Peter Zijlstra , Oleg Nesterov , Ingo Molnar , Vladimir Davydov , Kirill Tkhai Subject: Re: [PATCH v4] sched/numa: fix unsafe get_task_struct() in task_numa_assign() References: <1413962231.19914.130.camel@tkhai> In-Reply-To: <1413962231.19914.130.camel@tkhai> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/22/2014 03:17 AM, Kirill Tkhai wrote: > Unlocked access to dst_rq->curr in task_numa_compare() is racy. > If curr task is exiting this may be a reason of use-after-free: [...] I've complained about an unrelated issue in that part of the code a while back (https://lkml.org/lkml/2014/5/12/508) which PeterZ ended up fixing (https://lkml.org/lkml/2014/5/21/428) but it seems that both of us forgot to follow up on that and the fix never got upstream. Ever since this patch made it upstream, Peter's patch which I was carrying in my tree stopped applying and I've started seeing: [ 829.539183] BUG: spinlock recursion on CPU#10, trinity-c594/11067 [ 829.539203] lock: 0xffff880631dd6b80, .magic: dead4ead, .owner: trinity-c594/11067, .owner_cpu: 13 [ 829.539212] CPU: 10 PID: 11067 Comm: trinity-c594 Not tainted 3.18.0-rc3-next-20141106-sasha-00054-g09b7ccf-dirty #1448 [ 829.539226] 0000000000000000 0000000000000000 ffff880053acb000 ffff88032b71f828 [ 829.539235] ffffffffa009fb5a 0000000000000057 ffff880631dd6b80 ffff88032b71f868 [ 829.539243] ffffffff963f0c57 ffff880053acbd80 ffff880053acbdb0 ffff88032b71f858 [ 829.539246] Call Trace: [ 829.539265] dump_stack (lib/dump_stack.c:52) [ 829.539277] spin_dump (kernel/locking/spinlock_debug.c:68 (discriminator 8)) [ 829.539282] spin_bug (kernel/locking/spinlock_debug.c:76) [ 829.539288] do_raw_spin_lock (kernel/locking/spinlock_debug.c:84 kernel/locking/spinlock_debug.c:135) [ 829.539304] ? __schedule (kernel/sched/core.c:2803) [ 829.539313] _raw_spin_lock_irq (include/linux/spinlock_api_smp.h:129 kernel/locking/spinlock.c:167) [ 829.539321] ? task_numa_find_cpu (kernel/sched/fair.c:1258 kernel/sched/fair.c:1385) [ 829.539330] ? rcu_is_watching (./arch/x86/include/asm/preempt.h:95 kernel/rcu/tree.c:827) [ 829.539336] task_numa_find_cpu (kernel/sched/fair.c:1258 kernel/sched/fair.c:1385) [ 829.539342] ? task_numa_find_cpu (kernel/sched/fair.c:1253 kernel/sched/fair.c:1385) [ 829.539352] ? preempt_count_sub (kernel/sched/core.c:2644) [ 829.539358] task_numa_migrate (kernel/sched/fair.c:1452) [ 829.539364] ? task_numa_migrate (kernel/sched/fair.c:1391) [ 829.539376] ? kvm_clock_read (./arch/x86/include/asm/preempt.h:87 arch/x86/kernel/kvmclock.c:85) [ 829.539386] ? sched_clock (./arch/x86/include/asm/paravirt.h:192 arch/x86/kernel/tsc.c:304) [ 829.539392] ? sched_clock_local (kernel/sched/clock.c:202) [ 829.539399] numa_migrate_preferred (kernel/sched/fair.c:1539) [ 829.539404] ? sched_clock_local (kernel/sched/clock.c:202) [ 829.539411] task_numa_fault (kernel/sched/fair.c:2073) [ 829.539417] ? sched_clock_cpu (kernel/sched/clock.c:311) [ 829.539429] ? debug_smp_processor_id (lib/smp_processor_id.c:57) [ 829.539438] ? get_lock_stats (kernel/locking/lockdep.c:249) [ 829.539446] ? get_parent_ip (kernel/sched/core.c:2588) [ 829.539461] handle_mm_fault (mm/memory.c:3187 mm/memory.c:3233 mm/memory.c:3346 mm/memory.c:3375) [ 829.539466] ? find_vma (mm/mmap.c:2048) [ 829.539477] __do_page_fault (arch/x86/mm/fault.c:1246) [ 829.539485] ? context_tracking_user_exit (kernel/context_tracking.c:144) [ 829.539491] ? __this_cpu_preempt_check (lib/smp_processor_id.c:63) [ 829.539498] ? trace_hardirqs_off_caller (kernel/locking/lockdep.c:2640 (discriminator 8)) [ 829.539505] trace_do_page_fault (arch/x86/mm/fault.c:1329 include/linux/jump_label.h:114 include/linux/context_tracking_state.h:27 include/linux/context_tracking.h:45 arch/x86/mm/fault.c:1330) [ 829.539510] do_async_page_fault (arch/x86/kernel/kvm.c:280) [ 829.539516] async_page_fault (arch/x86/kernel/entry_64.S:1301) Thanks, Sasha -- 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/