From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f169.google.com (mail-pf0-f169.google.com [209.85.192.169]) by kanga.kvack.org (Postfix) with ESMTP id 90C826B0258 for ; Fri, 4 Dec 2015 08:43:21 -0500 (EST) Received: by pfu207 with SMTP id 207so26587947pfu.2 for ; Fri, 04 Dec 2015 05:43:21 -0800 (PST) Received: from m50-132.163.com (m50-132.163.com. [123.125.50.132]) by mx.google.com with ESMTP id w16si19526953pfa.221.2015.12.04.05.43.19 for ; Fri, 04 Dec 2015 05:43:20 -0800 (PST) Date: Fri, 4 Dec 2015 21:43:02 +0800 From: Geliang Tang Subject: Re: [PATCH v2] mm/slab.c: use list_{empty_careful,last_entry} in drain_freelist Message-ID: <20151204134302.GA6388@bogon> References: <3ea815dc52bf1a2bb5e324d7398315597900be84.1449151365.git.geliangtang@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Geliang Tang 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. > > 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? Thanks. - Geliang > > This patch seems to make it difficult to understand the code. -- 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