From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f173.google.com (mail-ig0-f173.google.com [209.85.213.173]) by kanga.kvack.org (Postfix) with ESMTP id D8FC06B0259 for ; Fri, 4 Dec 2015 11:16:40 -0500 (EST) Received: by igcmv3 with SMTP id mv3so39011920igc.0 for ; Fri, 04 Dec 2015 08:16:39 -0800 (PST) Received: from resqmta-ch2-02v.sys.comcast.net (resqmta-ch2-02v.sys.comcast.net. [2001:558:fe21:29:69:252:207:34]) by mx.google.com with ESMTPS id sa1si6914358igb.58.2015.12.04.08.16.39 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Fri, 04 Dec 2015 08:16:39 -0800 (PST) Date: Fri, 4 Dec 2015 10:16:38 -0600 (CST) From: Christoph Lameter Subject: Re: [PATCH v2] mm/slab.c: use list_{empty_careful,last_entry} in drain_freelist In-Reply-To: <20151204134302.GA6388@bogon> Message-ID: References: <3ea815dc52bf1a2bb5e324d7398315597900be84.1449151365.git.geliangtang@163.com> <20151204134302.GA6388@bogon> Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Geliang Tang Cc: Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Fri, 4 Dec 2015, Geliang Tang wrote: > On Thu, Dec 03, 2015 at 08:53:21AM -0600, Christoph Lameter wrote: > > On Thu, 3 Dec 2015, Geliang Tang wrote: > > > > > while (nr_freed < tofree && !list_empty(&n->slabs_free)) { > > > > > > spin_lock_irq(&n->list_lock); > > > - p = n->slabs_free.prev; > > > - if (p == &n->slabs_free) { > > > + if (list_empty_careful(&n->slabs_free)) { > > > > We have taken the lock. Why do we need to be "careful"? list_empty() > > shoudl work right? > > Yes. list_empty() is OK. > > > > > > spin_unlock_irq(&n->list_lock); > > > goto out; > > > } > > > > > > - page = list_entry(p, struct page, lru); > > > + page = list_last_entry(&n->slabs_free, struct page, lru); > > > > last??? > > The original code delete the page from the tail of slabs_free list. Maybe make the code clearer by using another method to get the page pointer? > > > > Would the the other new function that returns NULL on the empty list or > > the pointer not be useful here too and save some code? > > Sorry, I don't really understand what do you mean. Can you please specify > it a little bit? I take that back. list_empty is the best choice here. -- 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