From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f182.google.com (mail-pd0-f182.google.com [209.85.192.182]) by kanga.kvack.org (Postfix) with ESMTP id 7E28F6B0068 for ; Wed, 7 May 2014 17:29:28 -0400 (EDT) Received: by mail-pd0-f182.google.com with SMTP id v10so1515022pde.13 for ; Wed, 07 May 2014 14:29:28 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id hs1si2502332pbc.478.2014.05.07.14.29.27 for ; Wed, 07 May 2014 14:29:27 -0700 (PDT) Date: Wed, 7 May 2014 14:29:25 -0700 From: Andrew Morton Subject: Re: [patch] mm, slab: suppress out of memory warning unless debug is enabled Message-Id: <20140507142925.b0e31514d4cd8d5857b10850@linux-foundation.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Pekka Enberg , Christoph Lameter , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Wed, 7 May 2014 14:19:19 -0700 (PDT) David Rientjes wrote: > When the slab or slub allocators cannot allocate additional slab pages, they > emit diagnostic information to the kernel log such as current number of slabs, > number of objects, active objects, etc. This is always coupled with a page > allocation failure warning since it is controlled by !__GFP_NOWARN. > > Suppress this out of memory warning if the allocator is configured without debug > supported. The page allocation failure warning will indicate it is a failed > slab allocation, so this is only useful to diagnose allocator bugs. > > Since CONFIG_SLUB_DEBUG is already enabled by default for the slub allocator, > there is no functional change with this patch. If debug is disabled, however, > the warnings are now suppressed. > I'm not seeing any reason for making this change. > @@ -1621,11 +1621,17 @@ __initcall(cpucache_init); > static noinline void > slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid) > { > +#if DEBUG > struct kmem_cache_node *n; > struct page *page; > unsigned long flags; > int node; > > + if (gfpflags & __GFP_NOWARN) > + return; > + if (!printk_ratelimit()) > + return; printk_ratelimit() is lame - it uses a single global state. So if random net driver is using printk_ratelimit(), that driver and slab will interfere with each other. We don't appear to presently have a handy macro to do this properly - you might care to add one and switch printk_ratelimited() and pr_debug_ratelimited() over to using it. And various sites in include/linux/device.h, I guess. -- 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