From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757297AbbFPJEm (ORCPT ); Tue, 16 Jun 2015 05:04:42 -0400 Received: from foss.arm.com ([217.140.101.70]:36264 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932762AbbFPIsX (ORCPT ); Tue, 16 Jun 2015 04:48:23 -0400 Date: Tue, 16 Jun 2015 09:48:18 +0100 From: Catalin Marinas To: Larry Finger Cc: Tejun Heo , Martin KaFai Lau , Christoph Lameter , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [RFC NEXT] mm: Fix suspicious RCU usage at kernel/sched/core.c:7318 Message-ID: <20150616084818.GF21229@e104818-lin.cambridge.arm.com> References: <1434403518-5308-1-git-send-email-Larry.Finger@lwfinger.net> <20150616084424.GE21229@e104818-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150616084424.GE21229@e104818-lin.cambridge.arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 16, 2015 at 09:44:24AM +0100, Catalin Marinas wrote: > On Mon, Jun 15, 2015 at 10:25:18PM +0100, Larry Finger wrote: > > Beginning at commit d52d399, the following INFO splat is logged: > > > > [ 2.816564] =============================== > > [ 2.816986] [ INFO: suspicious RCU usage. ] > > [ 2.817402] 4.1.0-rc7-next-20150612 #1 Not tainted > > [ 2.817881] ------------------------------- > > [ 2.818297] kernel/sched/core.c:7318 Illegal context switch in RCU-bh read-side critical section! > > [ 2.819180] > > other info that might help us debug this: > > > > [ 2.819947] > > rcu_scheduler_active = 1, debug_locks = 0 > > [ 2.820578] 3 locks held by systemd/1: > > [ 2.820954] #0: (rtnl_mutex){+.+.+.}, at: [] rtnetlink_rcv+0x1f/0x40 > > [ 2.821855] #1: (rcu_read_lock_bh){......}, at: [] ipv6_add_addr+0x62/0x540 > > [ 2.822808] #2: (addrconf_hash_lock){+...+.}, at: [] ipv6_add_addr+0x184/0x540 > > [ 2.823790] > > stack backtrace: > > [ 2.824212] CPU: 0 PID: 1 Comm: systemd Not tainted 4.1.0-rc7-next-20150612 #1 > > [ 2.824932] Hardware name: TOSHIBA TECRA A50-A/TECRA A50-A, BIOS Version 4.20 04/17/2014 > > [ 2.825751] 0000000000000001 ffff880224e07838 ffffffff817263a4 ffffffff810ccf2a > > [ 2.826560] ffff880224e08000 ffff880224e07868 ffffffff810b6827 0000000000000000 > > [ 2.827368] ffffffff81a445d3 00000000000004f4 ffff88022682e100 ffff880224e07898 > > [ 2.828177] Call Trace: > > [ 2.828422] [] dump_stack+0x4c/0x6e > > [ 2.828937] [] ? console_unlock+0x1ca/0x510 > > [ 2.829514] [] lockdep_rcu_suspicious+0xe7/0x120 > > [ 2.830139] [] ___might_sleep+0x1d5/0x1f0 > > [ 2.830699] [] __might_sleep+0x4d/0x90 > > [ 2.831239] [] ? create_object+0x39/0x2e0 > > [ 2.831800] [] kmem_cache_alloc+0x47/0x250 > > [ 2.832375] [] ? find_next_zero_bit+0x1e/0x20 > > [ 2.832973] [] create_object+0x39/0x2e0 > > [ 2.833515] [] ? mark_held_locks+0x66/0x90 > > [ 2.834089] [] ? _raw_spin_unlock_irqrestore+0x4b/0x60 > > [ 2.834761] [] kmemleak_alloc_percpu+0x61/0xe0 > > [ 2.835369] [] pcpu_alloc+0x370/0x630 > > > > Additional backtrace lines are truncated. In addition, the above splat is > > followed by several "BUG: sleeping function called from invalid context > > at mm/slub.c:1268" outputs. As suggested by Martin KaFai Lau, these are the > > clue to the fix. Routine kmemleak_alloc_percpu() always uses GFP_KERNEL > > for its allocations, whereas it should use the value input to pcpu_alloc(). > > > > Signed-off-by: Larry Finger > > Cc: Martin KaFai Lau > > Cc: Catalin Marinas > > To: Tejun Heo > > Cc: Christoph Lameter > > Cc: linux-kernel@vger.kernel.org > > Cc: linux-mm@kvack.org [...] > Apart from the minor comment above (and the kmemleak.c.rej file): > > Reviewed-by: Catalin Marinas BTW, it's worth adding: Cc: # v3.18+ (or Fixes: 5835d96e9ce4 percpu: implement [__]alloc_percpu_gfp()) -- Catalin