From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f179.google.com (mail-wi0-f179.google.com [209.85.212.179]) by kanga.kvack.org (Postfix) with ESMTP id B1DFA6B0038 for ; Mon, 2 Mar 2015 15:33:08 -0500 (EST) Received: by widex7 with SMTP id ex7so17900470wid.4 for ; Mon, 02 Mar 2015 12:33:08 -0800 (PST) Received: from mail-wg0-x231.google.com (mail-wg0-x231.google.com. [2a00:1450:400c:c00::231]) by mx.google.com with ESMTPS id s9si24015281wjs.200.2015.03.02.12.33.06 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Mar 2015 12:33:07 -0800 (PST) Received: by wggy19 with SMTP id y19so35862494wgg.10 for ; Mon, 02 Mar 2015 12:33:06 -0800 (PST) Date: Mon, 2 Mar 2015 21:33:04 +0100 From: Michal Hocko Subject: Re: [RFC 3/4] sparc: remove __GFP_NOFAIL reuquirement Message-ID: <20150302203304.GA20513@dhcp22.suse.cz> References: <1425304483-7987-1-git-send-email-mhocko@suse.cz> <1425304483-7987-4-git-send-email-mhocko@suse.cz> <20150302.150405.2072800922470200977.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150302.150405.2072800922470200977.davem@davemloft.net> Sender: owner-linux-mm@kvack.org List-ID: To: David Miller Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hannes@cmpxchg.org, rientjes@google.com, david@fromorbit.com, tytso@mit.edu, mgorman@suse.de, penguin-kernel@I-love.SAKURA.ne.jp, sparclinux@vger.kernel.org, vipul@chelsio.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org On Mon 02-03-15 15:04:05, David S. Miller wrote: > From: Michal Hocko > Date: Mon, 2 Mar 2015 14:54:42 +0100 > > > mdesc_kmalloc is currently requiring __GFP_NOFAIL allocation although it > > seems that the allocation failure is handled by all callers (via > > mdesc_alloc). __GFP_NOFAIL is a strong liability for the memory > > allocator and so the users are discouraged to use the flag unless the > > allocation failure is really a nogo. Drop the flag here as this doesn't > > seem to be the case. > > > > Signed-off-by: Michal Hocko > > It is a serious failure. > > If we miss an MDESC update due to this allocation failure, the update > is not an event which gets retransmitted so we will lose the updated > machine description forever. > > We really need this allocation to succeed. OK, thanks for the clarification. This wasn't clear from the commit which has introduced this code. I will drop this patch. Would you accept something like the following instead? --- diff --git a/arch/sparc/kernel/mdesc.c b/arch/sparc/kernel/mdesc.c index 99632a87e697..26c80e18d7b1 100644 --- a/arch/sparc/kernel/mdesc.c +++ b/arch/sparc/kernel/mdesc.c @@ -130,26 +130,26 @@ static struct mdesc_mem_ops memblock_mdesc_ops = { static struct mdesc_handle *mdesc_kmalloc(unsigned int mdesc_size) { unsigned int handle_size; + struct mdesc_handle *hp; + unsigned long addr; void *base; handle_size = (sizeof(struct mdesc_handle) - sizeof(struct mdesc_hdr) + mdesc_size); + /* + * Allocation has to succeed because mdesc update would be missed + * and such events are not retransmitted. + */ base = kmalloc(handle_size + 15, GFP_KERNEL | __GFP_NOFAIL); - if (base) { - struct mdesc_handle *hp; - unsigned long addr; - - addr = (unsigned long)base; - addr = (addr + 15UL) & ~15UL; - hp = (struct mdesc_handle *) addr; + addr = (unsigned long)base; + addr = (addr + 15UL) & ~15UL; + hp = (struct mdesc_handle *) addr; - mdesc_handle_init(hp, handle_size, base); - return hp; - } + mdesc_handle_init(hp, handle_size, base); - return NULL; + return hp; } static void mdesc_kfree(struct mdesc_handle *hp) -- Michal Hocko SUSE Labs -- 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