From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f170.google.com (mail-pf0-f170.google.com [209.85.192.170]) by kanga.kvack.org (Postfix) with ESMTP id A80D182963 for ; Wed, 3 Feb 2016 18:30:49 -0500 (EST) Received: by mail-pf0-f170.google.com with SMTP id n128so22301337pfn.3 for ; Wed, 03 Feb 2016 15:30:49 -0800 (PST) Received: from mail-pf0-x22c.google.com (mail-pf0-x22c.google.com. [2607:f8b0:400e:c00::22c]) by mx.google.com with ESMTPS id z10si12195626pfi.50.2016.02.03.15.30.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Feb 2016 15:30:49 -0800 (PST) Received: by mail-pf0-x22c.google.com with SMTP id 65so22491399pfd.2 for ; Wed, 03 Feb 2016 15:30:49 -0800 (PST) Date: Wed, 3 Feb 2016 15:30:47 -0800 (PST) From: David Rientjes Subject: Re: [RFC][PATCH] mm, page_alloc: Warn on !__GFP_NOWARN allocation from IRQ context. In-Reply-To: <201602022233.FFF65148.QVOLOtOMFJHSFF@I-love.SAKURA.ne.jp> Message-ID: References: <201602022233.FFF65148.QVOLOtOMFJHSFF@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: mhocko@kernel.org, hannes@cmpxchg.org, jstancek@redhat.com, linux-mm@kvack.org On Tue, 2 Feb 2016, 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 > inside a loop. If the caller used __GFP_NOWARN, it would not have lasted > for 10 seconds. > Sounds like a ratelimiting issue in warn_alloc_failed() with nopage_rs. Would it be possible under certain configs to tweak this to not be so slow? Unfortunately, I don't think we can get away with adding a conditional to the page allocator hotpath for this, especially if it is only going to suggest a kernel patch :) -- 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