From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964818AbdKGViR (ORCPT ); Tue, 7 Nov 2017 16:38:17 -0500 Received: from mail-pf0-f194.google.com ([209.85.192.194]:54770 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934101AbdKGViM (ORCPT ); Tue, 7 Nov 2017 16:38:12 -0500 X-Google-Smtp-Source: ABhQp+RIO1zQTglcDTl9ISHCYyD3y9/ILkEKtPvn5R+wwbXp/OWEG7m2RgZSWCK5yz4jPI8eGxJE2g== Date: Tue, 7 Nov 2017 13:38:09 -0800 From: Kees Cook To: Andrew Morton , Jesper Dangaard Brouer Cc: Dave Hansen , Ying Huang , Vlastimil Babka , Michal Hocko , linux-kernel@vger.kernel.org Subject: [PATCH] mm, vmstat: Make sure mutex is a global static Message-ID: <20171107213809.GA4314@beast> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The mutex in sysctl_vm_numa_stat_handler() needs to be a global static, not a stack variable, otherwise it doesn't serve any purpose. Also, reading the file with CONFIG_LOCKDEP=y will complain: [ 63.258593] INFO: trying to register non-static key. [ 63.259113] the code is fine but needs lockdep annotation. [ 63.259596] turning off the locking correctness validator. [ 63.260073] CPU: 1 PID: 4102 Comm: perl Not tainted 4.14.0-rc8-next-20171107+ #419 [ 63.260769] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 [ 63.261570] Call Trace: [ 63.261783] dump_stack+0x5f/0x86 [ 63.262062] register_lock_class+0xe4/0x550 [ 63.262408] ? __lock_acquire+0x308/0x1170 [ 63.262746] __lock_acquire+0x7e/0x1170 [ 63.263063] lock_acquire+0x9d/0x1d0 [ 63.263363] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0 [ 63.263777] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0 [ 63.264192] __mutex_lock+0xb8/0x9a0 [ 63.264488] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0 [ 63.264942] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0 [ 63.265398] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0 [ 63.265840] sysctl_vm_numa_stat_handler+0x8f/0x2d0 [ 63.266270] proc_sys_call_handler+0xe3/0x100 [ 63.266655] __vfs_read+0x33/0x1b0 [ 63.266957] vfs_read+0xa6/0x150 [ 63.267244] SyS_read+0x55/0xc0 [ 63.267525] do_syscall_64+0x56/0x140 [ 63.267850] entry_SYSCALL64_slow_path+0x25/0x25 Fixes: 920d5f77d1a25 ("mm, sysctl: make NUMA stats configurable") Cc: Jesper Dangaard Brouer Cc: Dave Hansen Cc: Ying Huang Cc: Vlastimil Babka Cc: Michal Hocko Signed-off-by: Kees Cook --- mm/vmstat.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/vmstat.c b/mm/vmstat.c index e0593434fd58..40b2db6db6b1 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -72,11 +72,12 @@ static void invalid_numa_statistics(void) zero_global_numa_counters(); } +static DEFINE_MUTEX(vm_numa_stat_lock); + int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write, void __user *buffer, size_t *length, loff_t *ppos) { int ret, oldval; - DEFINE_MUTEX(vm_numa_stat_lock); mutex_lock(&vm_numa_stat_lock); if (write) -- 2.7.4 -- Kees Cook Pixel Security