From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753066AbaHDVXh (ORCPT ); Mon, 4 Aug 2014 17:23:37 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33856 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751746AbaHDVXf (ORCPT ); Mon, 4 Aug 2014 17:23:35 -0400 Date: Mon, 4 Aug 2014 14:23:33 -0700 From: Andrew Morton To: Joonsoo Kim Cc: Sasha Levin , Christoph Lameter , LKML , Dave Jones , Matt Mackall , Gilad Ben-Yossef , Jens Axboe , Pekka Enberg , David Rientjes Subject: Re: kernel: smp: WARNING at kernel/smp.c:673 Message-Id: <20140804142333.727754f0c294e8fa11a530c8@linux-foundation.org> In-Reply-To: <20140804064823.GB22835@js1304-P5Q-DELUXE> References: <53DEF67E.8090004@oracle.com> <20140804064823.GB22835@js1304-P5Q-DELUXE> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 4 Aug 2014 15:48:23 +0900 Joonsoo Kim wrote: > > While fuzzing with trinity inside a KVM tools guest running the latest -next > > kernel, I've stumbled on the following spew: > > > > > > [ 1226.701012] WARNING: CPU: 6 PID: 8624 at kernel/smp.c:673 on_each_cpu_cond+0x27f/0x2f0() > > [ 1226.703128] Modules linked in: > > [ 1226.703955] CPU: 6 PID: 8624 Comm: trinity-c26 Tainted: G W 3.16.0-rc7-next-20140801-sasha-00047-gd6ce559 #991 > > [ 1226.706792] ffff881b2e8a3000 0000000023830039 0000000000000000 ffff881b2e8a3000 > > [ 1226.708179] ffff881ada5b3978 ffffffffa1ee96b4 0000000000000000 ffff881ada5b39b8 > > [ 1226.709610] ffffffff9d1ce5ba ffffffff9d2c0ddf 000000000000001b ffff8807d7608000 > > [ 1226.710966] Call Trace: > > [ 1226.711417] dump_stack (lib/dump_stack.c:52) > > [ 1226.712311] warn_slowpath_common (kernel/panic.c:432) > > [ 1226.715425] warn_slowpath_null (kernel/panic.c:466) > > [ 1226.716436] on_each_cpu_cond (kernel/smp.c:673 (discriminator 3)) > > [ 1226.720821] __kmem_cache_shrink (mm/slub.c:3420) > > [ 1226.722711] slab_memory_callback (mm/slub.c:3464 mm/slub.c:3556) > > [ 1226.723925] notifier_call_chain (kernel/notifier.c:93) > > [ 1226.725244] __blocking_notifier_call_chain (kernel/notifier.c:319) > > [ 1226.726310] blocking_notifier_call_chain (kernel/notifier.c:329) > > [ 1226.727263] memory_notify (drivers/base/memory.c:177) > > [ 1226.728210] __offline_pages.constprop.23 (include/linux/notifier.h:179 mm/memory_hotplug.c:1682) > > [ 1226.731896] offline_pages (mm/memory_hotplug.c:1787) > > [ 1226.733095] memory_subsys_offline (drivers/base/memory.c:267 drivers/base/memory.c:304) > > [ 1226.735208] device_offline (drivers/base/core.c:1428) > > [ 1226.736966] online_store (drivers/base/core.c:451 (discriminator 2)) > > [ 1226.737720] dev_attr_store (drivers/base/core.c:138) > > [ 1226.739986] sysfs_kf_write (fs/sysfs/file.c:116) > > [ 1226.742105] kernfs_fop_write (fs/kernfs/file.c:308) > > [ 1226.743058] do_loop_readv_writev (fs/read_write.c:708) > > [ 1226.745095] do_readv_writev (fs/read_write.c:840) > > [ 1226.752769] vfs_writev (fs/read_write.c:879) > > [ 1226.753755] SyS_writev (fs/read_write.c:911 fs/read_write.c:903) > > [ 1226.754660] tracesys (arch/x86/kernel/entry_64.S:541) > > > > No time to dig too much into this today, will work on it tomorrow. > > I think that that WARN_ON_ONCE() in kernel/smp.c:673 is wrong. > smp_call_function_single() returns 0 if success so it should be > WARN_ON_ONCE(ret) rather than WARN_ON_ONCE(!ret). Surely true. From: Andrew Morton Subject: kernel/smp.c:on_each_cpu_cond(): fix warning in fallback path The rarely-executed memry-allocation-failed callback path generates a WARN_ON_ONCE() when smp_call_function_single() succeeds. Presumably it's supposed to warn on failures. Reported-by: Sasha Levin Cc: Christoph Lameter Cc: Gilad Ben-Yossef Cc: David Rientjes Cc: Joonsoo Kim Cc: Tejun Heo Cc: Signed-off-by: Andrew Morton --- kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN kernel/smp.c~a kernel/smp.c --- a/kernel/smp.c~a +++ a/kernel/smp.c @@ -661,7 +661,7 @@ void on_each_cpu_cond(bool (*cond_func)( if (cond_func(cpu, info)) { ret = smp_call_function_single(cpu, func, info, wait); - WARN_ON_ONCE(!ret); + WARN_ON_ONCE(ret); } preempt_enable(); } _