From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 73C046B0038 for ; Tue, 20 Sep 2016 17:06:41 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id v67so59914224pfv.1 for ; Tue, 20 Sep 2016 14:06:41 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id bf3si9000944pad.100.2016.09.20.14.06.40 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Sep 2016 14:06:40 -0700 (PDT) Date: Tue, 20 Sep 2016 14:06:39 -0700 From: Andrew Morton Subject: Re: [PATCH] mm,ksm: add __GFP_HIGH to the allocation in alloc_stable_node() Message-Id: <20160920140639.2f1ea83784d994699e713c2e@linux-foundation.org> In-Reply-To: <1474354484-58233-1-git-send-email-zhongjiang@huawei.com> References: <1474354484-58233-1-git-send-email-zhongjiang@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: zhongjiang Cc: hughd@google.com, mhocko@suse.cz, vbabka@suse.cz, rientjes@google.com, linux-mm@kvack.org On Tue, 20 Sep 2016 14:54:44 +0800 zhongjiang wrote: > From: zhong jiang > > Accoding to HUgh's suggestion, alloc_stable_node() with GFP_KERNEL > will cause the hungtask, despite less possiblity. > > At present, if alloc_stable_node allocate fails, two break_cow may > want to allocate a couple of pages, and the issue will come up when > free memory is under pressure. > > we fix it by adding the __GFP_HIGH to GFP. because it grant access to > some of meory reserves. it will make progess to make it allocation > successful at the utmost. > > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -299,7 +299,7 @@ static inline void free_rmap_item(struct rmap_item *rmap_item) > > static inline struct stable_node *alloc_stable_node(void) > { > - return kmem_cache_alloc(stable_node_cache, GFP_KERNEL); > + return kmem_cache_alloc(stable_node_cache, GFP_KERNEL | __GFP_HIGH); > } > > static inline void free_stable_node(struct stable_node *stable_node) It is very hard for a reader to understand why this __GFP_HIGH is being used here, so we should have a code comment explaining the reasoning, please. -- 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