From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 28EF65F0001 for ; Wed, 15 Apr 2009 06:13:12 -0400 (EDT) Received: by fxm22 with SMTP id 22so3778246fxm.38 for ; Wed, 15 Apr 2009 03:13:21 -0700 (PDT) Date: Wed, 15 Apr 2009 12:13:17 +0200 From: Andrea Righi Subject: Re: [PATCH] memcg remove warning at DEBUG_VM=off Message-ID: <20090415101317.GA3240@linux> References: <20090408142042.3fb62eea.kamezawa.hiroyu@jp.fujitsu.com> <20090408052715.GX7082@balbir.in.ibm.com> <20090409222512.bd026a40.akpm@linux-foundation.org> <20090410153335.b52c5f74.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20090410153335.b52c5f74.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Andrew Morton , balbir@linux.vnet.ibm.com, "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "nishimura@mxp.nes.nec.co.jp" List-ID: On Fri, Apr 10, 2009 at 03:33:35PM +0900, KAMEZAWA Hiroyuki wrote: > On Thu, 9 Apr 2009 22:25:12 -0700 > Andrew Morton wrote: > > > On Wed, 8 Apr 2009 10:57:15 +0530 Balbir Singh wrote: > > > > > * KAMEZAWA Hiroyuki [2009-04-08 14:20:42]: > > > > > > > From: KAMEZAWA Hiroyuki > > > > This is against 2.6.30-rc1. (maybe no problem against mmotm.) > > > > > > > > == > > > > Fix warning as > > > > > > > > CC mm/memcontrol.o > > > > mm/memcontrol.c:318: warning: ?$B!Fmem_cgroup_is_obsolete?$B!G defined but not used > > > > > > > > This is called only from VM_BUG_ON(). > > > > > > > > Signed-off-by: KAMEZAWA Hiroyuki > > > > --- > > > > Index: linux-2.6.30-rc1/mm/memcontrol.c > > > > =================================================================== > > > > --- linux-2.6.30-rc1.orig/mm/memcontrol.c > > > > +++ linux-2.6.30-rc1/mm/memcontrol.c > > > > @@ -314,13 +314,14 @@ static struct mem_cgroup *try_get_mem_cg > > > > return mem; > > > > } > > > > > > > > +#ifdef CONFIG_DEBUG_VM > > > > static bool mem_cgroup_is_obsolete(struct mem_cgroup *mem) > > > > { > > > > if (!mem) > > > > return true; > > > > return css_is_removed(&mem->css); > > > > } > > > > - > > > > +#endif > > > > > > Can we change the code to use > > > > > > VM_BUG_ON(!mem || css_is_removed(&mem->css)); > > > > > > > yup. > > > > --- a/mm/memcontrol.c~memcg-remove-warning-when-config_debug_vm=n-fix > > +++ a/mm/memcontrol.c > > @@ -314,14 +314,13 @@ static struct mem_cgroup *try_get_mem_cg > > return mem; > > } > > > > -#ifdef CONFIG_DEBUG_VM > > static bool mem_cgroup_is_obsolete(struct mem_cgroup *mem) > > { > > if (!mem) > > return true; > > return css_is_removed(&mem->css); > > } > > -#endif > > + > > > > /* > > * Call callback function against all cgroup under hierarchy tree. > > @@ -933,7 +932,7 @@ static int __mem_cgroup_try_charge(struc > > if (unlikely(!mem)) > > return 0; > > > > - VM_BUG_ON(mem_cgroup_is_obsolete(mem)); > > + VM_BUG_ON(!mem || mem_cgroup_is_obsolete(mem)); > > > > while (1) { > > int ret; > > _ > > > > Although it really should be > > > > VM_BUG_ON(!mem); > > VM_BUG_ON(mem_cgroup_is_obsolete(mem)); > > > > because if that BUG triggers, you'll be wondering which case caused it. > > > Ah, sorry, I missed the reply. > maybe calling css_is_removed() directly is a choice. > I'll prepare v2. > > Regards, > -Kame The warning is still there actually. I've just written a fix and seen this discussion, maybe I can offload a little bit Kame. ;) -Andrea --- memcg: remove warning when CONFIG_DEBUG_VM is not set Fix the following warning removing mem_cgroup_is_obsolete(): mm/memcontrol.c:318: warning: a??mem_cgroup_is_obsoletea?? defined but not used Moreover, split the VM_BUG_ON() checks in two parts to be aware of which one triggered the bug. Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Andrea Righi --- mm/memcontrol.c | 11 ++--------- 1 files changed, 2 insertions(+), 9 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e44fb0f..8cd6358 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -314,14 +314,6 @@ static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) return mem; } -static bool mem_cgroup_is_obsolete(struct mem_cgroup *mem) -{ - if (!mem) - return true; - return css_is_removed(&mem->css); -} - - /* * Call callback function against all cgroup under hierarchy tree. */ @@ -932,7 +924,8 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, if (unlikely(!mem)) return 0; - VM_BUG_ON(!mem || mem_cgroup_is_obsolete(mem)); + VM_BUG_ON(!mem); + VM_BUG_ON(css_is_removed(&mem->css)); while (1) { int ret; -- 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