From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f197.google.com (mail-wj0-f197.google.com [209.85.210.197]) by kanga.kvack.org (Postfix) with ESMTP id 2840E6B0069 for ; Thu, 19 Jan 2017 02:29:49 -0500 (EST) Received: by mail-wj0-f197.google.com with SMTP id ez4so6756607wjd.2 for ; Wed, 18 Jan 2017 23:29:49 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id v6si14310633wmv.50.2017.01.18.23.29.47 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 18 Jan 2017 23:29:47 -0800 (PST) Subject: Re: [patch -mm] mm, page_alloc: warn_alloc nodemask is NULL when cpusets are disabled References: From: Vlastimil Babka Message-ID: <279f10c2-3eaa-c641-094f-3070db67d84f@suse.cz> Date: Thu, 19 Jan 2017 08:29:45 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes , Andrew Morton , Michal Hocko Cc: Johannes Weiner , Mel Gorman , linux-mm@kvack.org, LKML On 01/18/2017 10:51 PM, David Rientjes wrote: > The patch "mm, page_alloc: warn_alloc print nodemask" implicitly sets the > allocation nodemask to cpuset_current_mems_allowed when there is no > effective mempolicy. cpuset_current_mems_allowed is only effective when > cpusets are enabled, which is also printed by warn_alloc(), so setting > the nodemask to cpuset_current_mems_allowed is redundant and prevents > debugging issues where ac->nodemask is not set properly in the page > allocator. > > This provides better debugging output since > cpuset_print_current_mems_allowed() is already provided. > > Signed-off-by: David Rientjes Yes, with my current cpuset vs mempolicy debugging experience, this is more useful (except how both nodemask and mems_allowed can change under us, so what we print here is not necessarily the same that what get_page_from_freelist() has seen, but that's another thing...). But I would suggest you change the oom killer's dump_header() the same way than warn_alloc(). Thanks, Vlastimil > --- > mm/page_alloc.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3037,7 +3037,6 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...) > va_list args; > static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL, > DEFAULT_RATELIMIT_BURST); > - nodemask_t *nm = (nodemask) ? nodemask : &cpuset_current_mems_allowed; > > if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) || > debug_guardpage_minorder() > 0) > @@ -3051,11 +3050,16 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...) > pr_cont("%pV", &vaf); > va_end(args); > > - pr_cont(", mode:%#x(%pGg), nodemask=%*pbl\n", gfp_mask, &gfp_mask, nodemask_pr_args(nm)); > + pr_cont(", mode:%#x(%pGg), nodemask=", gfp_mask, &gfp_mask); > + if (nodemask) > + pr_cont("%*pbl\n", nodemask_pr_args(nodemask)); > + else > + pr_cont("(null)\n"); > + > cpuset_print_current_mems_allowed(); > > dump_stack(); > - warn_alloc_show_mem(gfp_mask, nm); > + warn_alloc_show_mem(gfp_mask, nodemask); > } > > static inline struct page * > -- 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