From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f175.google.com (mail-pf0-f175.google.com [209.85.192.175]) by kanga.kvack.org (Postfix) with ESMTP id 5F6B2828DF for ; Wed, 3 Feb 2016 05:41:04 -0500 (EST) Received: by mail-pf0-f175.google.com with SMTP id w123so12004153pfb.0 for ; Wed, 03 Feb 2016 02:41:04 -0800 (PST) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id 137si8577626pfb.80.2016.02.03.02.41.03 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 03 Feb 2016 02:41:03 -0800 (PST) Subject: Re: [RFC][PATCH] mm, page_alloc: Warn on !__GFP_NOWARN allocation from IRQ context. From: Tetsuo Handa References: <201602022233.FFF65148.QVOLOtOMFJHSFF@I-love.SAKURA.ne.jp> <20160202161421.GA30012@cmpxchg.org> In-Reply-To: <20160202161421.GA30012@cmpxchg.org> Message-Id: <201602031940.IFH52643.JLOOFtMQOFFHVS@I-love.SAKURA.ne.jp> Date: Wed, 3 Feb 2016 19:40:52 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: hannes@cmpxchg.org Cc: mhocko@kernel.org, rientjes@google.com, jstancek@redhat.com, linux-mm@kvack.org Johannes Weiner wrote: > On Tue, Feb 02, 2016 at 10:33:22PM +0900, Tetsuo Handa wrote: > > >From 20b3c1c9ef35547395c3774c6208a867cf0046d4 Mon Sep 17 00:00:00 2001 > > From: Tetsuo Handa > > Date: Tue, 2 Feb 2016 16:50:45 +0900 > > Subject: [RFC][PATCH] mm, page_alloc: Warn on !__GFP_NOWARN allocation from IRQ context. > > > > Jan Stancek hit a hard lockup problem due to flood of memory allocation > > failure messages which lasted for 10 seconds with IRQ disabled. Printing > > traces using warn_alloc_failed() is very slow (which can take up to about > > 1 second for each warn_alloc_failed() call). The caller used GFP_NOWARN s/GFP_NOWARN/GFP_NOWAIT/ > > inside a loop. If the caller used __GFP_NOWARN, it would not have lasted > > for 10 seconds. > > Who is doing page allocations in a loop with irqs disabled?! lib/dma-debug.c functions which are called with irqs disabled. http://lkml.kernel.org/r/201601292135.DHG60988.SOQFJFOHFVMLOt@I-love.SAKURA.ne.jp > > And then, why does it take that long? Is that a serial console? Most > of the output is KERN_INFO, it might be better to raise the loglevel > and still have all the debugging output in the logs. Yes, I think it is a serial console. -- 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