From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f42.google.com (mail-pa0-f42.google.com [209.85.220.42]) by kanga.kvack.org (Postfix) with ESMTP id 86F5A6B011C for ; Tue, 18 Mar 2014 17:22:19 -0400 (EDT) Received: by mail-pa0-f42.google.com with SMTP id fb1so7941101pad.29 for ; Tue, 18 Mar 2014 14:22:19 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id m9si13332225pab.44.2014.03.18.14.22.18 for ; Tue, 18 Mar 2014 14:22:18 -0700 (PDT) Date: Tue, 18 Mar 2014 14:22:16 -0700 From: Andrew Morton Subject: Re: kswapd using __this_cpu_add() in preemptible code Message-Id: <20140318142216.317bf986d10a564881791100@linux-foundation.org> In-Reply-To: <20140318185329.GB430@swordfish> References: <20140318185329.GB430@swordfish> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Sergey Senozhatsky Cc: Alexander Viro , Mel Gorman , Michal Hocko , Rik van Riel , Johannes Weiner , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter On Tue, 18 Mar 2014 21:53:30 +0300 Sergey Senozhatsky wrote: > Hello gentlemen, > > Commit 589a606f9539663f162e4a110d117527833b58a4 ("percpu: add preemption > checks to __this_cpu ops") added preempt check to used in __count_vm_events() > __this_cpu ops, causing the following kswapd warning: > > BUG: using __this_cpu_add() in preemptible [00000000] code: kswapd0/56 > caller is __this_cpu_preempt_check+0x2b/0x2d > Call Trace: > [] dump_stack+0x4e/0x7a > [] check_preemption_disabled+0xce/0xdd > [] __this_cpu_preempt_check+0x2b/0x2d > [] inode_lru_isolate+0xed/0x197 > [] list_lru_walk_node+0x7b/0x14c > [] ? iput+0x131/0x131 > [] prune_icache_sb+0x35/0x4c > [] super_cache_scan+0xe3/0x143 > [] shrink_slab_node+0x103/0x16f > [] shrink_slab+0x75/0xe4 > [] balance_pgdat+0x2fa/0x47f > [] kswapd+0x2d3/0x2fd > [] ? __wake_up_sync+0xd/0xd > [] ? balance_pgdat+0x47f/0x47f > [] kthread+0xd6/0xde > [] ? kthread_create_on_node+0x162/0x162 > [] ret_from_fork+0x7c/0xb0 > [] ? kthread_create_on_node+0x162/0x162 > > > list_lru_walk_node() seems to be the only place where __count_vm_events() > called with preemption enabled. remaining __count_vm_events() and > __count_vm_event() calls are done with preemption disabled (unless I > overlooked something). Christoph caught one. How does this look? From: Andrew Morton Subject: fs/inode.c:inode_lru_isolate(): use atomic count_vm_events() "percpu: add preemption checks to __this_cpu ops" added preempt check to used in __count_vm_events() __this_cpu ops, causing the following kswapd warning: BUG: using __this_cpu_add() in preemptible [00000000] code: kswapd0/56 caller is __this_cpu_preempt_check+0x2b/0x2d Call Trace: [] dump_stack+0x4e/0x7a [] check_preemption_disabled+0xce/0xdd [] __this_cpu_preempt_check+0x2b/0x2d [] inode_lru_isolate+0xed/0x197 [] list_lru_walk_node+0x7b/0x14c [] ? iput+0x131/0x131 [] prune_icache_sb+0x35/0x4c Switch from __count_vm_events() to the preempt-safe count_vm_events(). Reported-by: Sergey Senozhatsky Cc: Christoph Lameter Signed-off-by: Andrew Morton --- fs/inode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN fs/inode.c~fs-inodec-inode_lru_isolate-use-atomic-count_vm_events fs/inode.c --- a/fs/inode.c~fs-inodec-inode_lru_isolate-use-atomic-count_vm_events +++ a/fs/inode.c @@ -722,9 +722,9 @@ inode_lru_isolate(struct list_head *item unsigned long reap; reap = invalidate_mapping_pages(&inode->i_data, 0, -1); if (current_is_kswapd()) - __count_vm_events(KSWAPD_INODESTEAL, reap); + count_vm_events(KSWAPD_INODESTEAL, reap); else - __count_vm_events(PGINODESTEAL, reap); + count_vm_events(PGINODESTEAL, reap); if (current->reclaim_state) current->reclaim_state->reclaimed_slab += reap; } _ -- 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