From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f174.google.com (mail-pd0-f174.google.com [209.85.192.174]) by kanga.kvack.org (Postfix) with ESMTP id 5A3AF6B0031 for ; Thu, 6 Mar 2014 13:32:33 -0500 (EST) Received: by mail-pd0-f174.google.com with SMTP id y13so2876631pdi.19 for ; Thu, 06 Mar 2014 10:32:33 -0800 (PST) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.11.231]) by mx.google.com with ESMTPS id wh4si5707359pbc.297.2014.03.06.10.32.32 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Mar 2014 10:32:32 -0800 (PST) Date: Thu, 6 Mar 2014 12:29:41 -0600 From: Josh Cartwright Subject: [PATCH -next] slub: Replace __this_cpu_inc usage w/ SLUB_STATS Message-ID: <20140306182941.GH18529@joshc.qualcomm.com> References: <20140306194821.3715d0b6212cc10415374a68@canb.auug.org.au> <20140306155316.GG18529@joshc.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140306155316.GG18529@joshc.qualcomm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Stephen Rothwell Cc: linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Lameter , Pekka Enberg , Matt Mackall , linux-mm@kvack.org On Thu, Mar 06, 2014 at 09:53:16AM -0600, Josh Cartwright wrote: > Booting on my Samsung Series 9 laptop gives me loads and loads of BUGs > triggered by __this_cpu_add(), making making the system completely > unusable: > > [ 5.808326] BUG: using __this_cpu_add() in preemptible [00000000] code: swapper/0/1 > [ 5.812331] caller is __this_cpu_preempt_check+0x2b/0x30 > [ 5.815654] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc5-next-20140306-joshc-08290-g0ffb2fe #1 > [ 5.819553] Hardware name: SAMSUNG ELECTRONICS CO., LTD. 900X3C/900X3D/900X3E/900X4C/900X4D/NP900X3E-A02US, BIOS P07ABK 04/09/2013 > [ 5.823558] ffff8801182157c0 ffff880118215790 ffffffff81a64cec 0000000000000000 > [ 5.827177] ffff8801182157b0 ffffffff81462360 ffff8800c3d553e0 ffffea00030f5500 > [ 5.830744] ffff8801182157e8 ffffffff814623bb 635f736968745f5f 29286464615f7570 > [ 5.834134] Call Trace: > [ 5.836848] [] dump_stack+0x4e/0x7a > [ 5.839943] [] check_preemption_disabled+0xd0/0xe0 > [ 5.842997] [] __this_cpu_preempt_check+0x2b/0x30 > [ 5.846022] [] __slab_free+0x38/0x590 > [ 5.848863] [] ? get_parent_ip+0xd/0x50 > [ 5.850467] BUG: using __this_cpu_add() in preemptible [00000000] code: khubd/36 > [ 5.850472] caller is __this_cpu_preempt_check+0x2b/0x30 > [ 5.859125] [] ? preempt_count_sub+0x6b/0xf0 > [ 5.862521] [] ? _raw_spin_unlock_irqrestore+0x4a/0x80 > [ 5.865599] [] ? __debug_check_no_obj_freed+0x13e/0x240 > [ 5.868738] [] ? __this_cpu_preempt_check+0x2b/0x30 > [ 5.871799] [] kfree+0x2f7/0x300 FWIW, it looks like the magic combination of options are: - CONFIG_DEBUG_PREEMPT=y - CONFIG_SLUB=y - CONFIG_SLUB_STATS=y Looks like the new percpu() checks are complaining about SLUB's use of __this_cpu_inc() for maintaining it's stat counters. The below patch seems to fix it. Although, I'm wondering how exact these statistics need to be. Is making them preemption safe even a concern? Thanks, Josh --8<-- Make slub statistics maintenance preemption-safe. Fixes the following warning when CONFIG_SLUB_STATS and CONFIG_DEBUG_PREEMPT: BUG: using __this_cpu_add() in preemptible [00000000] code: systemd-journal/226 caller is __this_cpu_preempt_check+0x2b/0x30 Call Trace: dump_stack+0x4e/0x7a check_preemption_disabled+0xd0/0xe0 __this_cpu_preempt_check+0x2b/0x30 __slab_free+0x38/0x590 kmem_cache_free+0x367/0x3a0 jbd2_journal_stop+0x24d/0x500 __ext4_journal_stop+0x37/0x90 ext4_truncate+0x1ab/0x570 ext4_setattr+0x2d3/0x810 notify_change+0x159/0x3a0 do_truncate+0x6f/0xa0 do_sys_ftruncate.constprop.18+0x10e/0x160 SyS_ftruncate+0xe/0x10 system_call_fastpath+0x1a/0x1f Cc: Christoph Lameter Signed-off-by: Josh Cartwright --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index c6eb29d..c873e61 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -224,7 +224,7 @@ static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { } static inline void stat(const struct kmem_cache *s, enum stat_item si) { #ifdef CONFIG_SLUB_STATS - __this_cpu_inc(s->cpu_slab->stat[si]); + this_cpu_inc(s->cpu_slab->stat[si]); #endif } -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- 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