From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 3F9E06B0044 for ; Tue, 27 Jan 2009 16:53:54 -0500 (EST) Message-ID: <497F8172.7000403@cs.helsinki.fi> Date: Tue, 27 Jan 2009 23:49:38 +0200 From: Pekka Enberg MIME-Version: 1.0 Subject: Re: [PATCH] kmalloc: Return NULL instead of link failure References: <4975F376.4010506@suse.com> <20090127133723.46eb7035.akpm@linux-foundation.org> In-Reply-To: <20090127133723.46eb7035.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Jeff Mahoney , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Andrew Morton wrote: > On Tue, 20 Jan 2009 10:53:26 -0500 > Jeff Mahoney wrote: > >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> The SLAB kmalloc with a constant value isn't consistent with the other >> implementations because it bails out with __you_cannot_kmalloc_that_much >> rather than returning NULL and properly allowing the caller to fall back >> to vmalloc or take other action. This doesn't happen with a non-constant >> value or with SLOB or SLUB. >> >> Starting with 2.6.28, I've been seeing build failures on s390x. This is >> due to init_section_page_cgroup trying to allocate 2.5MB when the max >> size for a kmalloc on s390x is 2MB. >> >> It's failing because the value is constant. The workarounds at the call >> size are ugly and the caller shouldn't have to change behavior depending >> on what the backend of the API is. >> >> So, this patch eliminates the link failure and returns NULL like the >> other implementations. >> > > OK by me, is that's what the other sl[abcd...xyz]b.c implementations > do. > > That __you_cannot_kmalloc_that_much() thing has frequently been a PITA > anyway - some gcc versions flub the constant_p() test and end up > referencing __you_cannot_kmalloc_that_much() when the callsite was > passing a variable `size' arg. [snip] > Strange patch format, but it applied. > > I'll punt this patch in the Pekka direction. Applied, thanks! Pekka -- 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