Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934641Ab3DKQm1 (ORCPT ); Thu, 11 Apr 2013 12:42:27 -0400 Received: from g1t0026.austin.hp.com ([15.216.28.33]:6753 "EHLO g1t0026.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756562Ab3DKQm0 (ORCPT ); Thu, 11 Apr 2013 12:42:26 -0400 Message-ID: <1365697802.32127.117.camel@misato.fc.hp.com> Subject: Re: [PATCH v3 2/3] resource: Add release_mem_region_adjustable() From: Toshi Kani To: Andrew Morton Cc: David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxram@us.ibm.com, guz.fnst@cn.fujitsu.com, tmac@hp.com, isimatu.yasuaki@jp.fujitsu.com, wency@cn.fujitsu.com, tangchen@cn.fujitsu.com, jiang.liu@huawei.com Date: Thu, 11 Apr 2013 10:30:02 -0600 In-Reply-To: <20130410152404.e0836af597ba3545b9846672@linux-foundation.org> References: <1365614221-685-1-git-send-email-toshi.kani@hp.com> <1365614221-685-3-git-send-email-toshi.kani@hp.com> <20130410144412.395bf9f2fb8192920175e30a@linux-foundation.org> <1365630585.32127.110.camel@misato.fc.hp.com> <20130410152404.e0836af597ba3545b9846672@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4 (3.6.4-3.fc18) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3215 Lines: 111 On Wed, 2013-04-10 at 15:24 -0700, Andrew Morton wrote: > On Wed, 10 Apr 2013 15:08:29 -0700 (PDT) David Rientjes wrote: > > > On Wed, 10 Apr 2013, Toshi Kani wrote: > > > > > > I'll switch it to GFP_ATOMIC. Which is horridly lame but the > > > > allocation is small and alternatives are unobvious. > > > > > > Great! Again, thanks for the update! > > > > release_mem_region_adjustable() allocates at most one struct resource, so > > why not do kmalloc(sizeof(struct resource), GFP_KERNEL) before taking > > resource_lock and then testing whether it's NULL or not when splitting? > > It unnecessarily allocates memory when there's no split, but > > __remove_pages() shouldn't be a hotpath. > > yup. > > --- a/kernel/resource.c~resource-add-release_mem_region_adjustable-fix-fix > +++ a/kernel/resource.c > @@ -1046,7 +1046,8 @@ int release_mem_region_adjustable(struct > resource_size_t start, resource_size_t size) > { > struct resource **p; > - struct resource *res, *new; > + struct resource *res; > + struct resource *new_res; > resource_size_t end; > int ret = -EINVAL; > > @@ -1054,6 +1055,9 @@ int release_mem_region_adjustable(struct > if ((start < parent->start) || (end > parent->end)) > return ret; > > + /* The kzalloc() result gets checked later */ > + new_res = kzalloc(sizeof(struct resource), GFP_KERNEL); > + > p = &parent->child; > write_lock(&resource_lock); > > @@ -1091,32 +1095,33 @@ int release_mem_region_adjustable(struct > start - res->start); > } else { > /* split into two entries */ > - new = kzalloc(sizeof(struct resource), GFP_ATOMIC); > - if (!new) { > + if (!new_res) { > ret = -ENOMEM; > break; > } > - new->name = res->name; > - new->start = end + 1; > - new->end = res->end; > - new->flags = res->flags; > - new->parent = res->parent; > - new->sibling = res->sibling; > - new->child = NULL; > + new_res->name = res->name; > + new_res->start = end + 1; > + new_res->end = res->end; > + new_res->flags = res->flags; > + new_res->parent = res->parent; > + new_res->sibling = res->sibling; > + new_res->child = NULL; > > ret = __adjust_resource(res, res->start, > start - res->start); > if (ret) { > - kfree(new); > + kfree(new_res); > break; > } The kfree() in the if-statement above is not necessary since kfree() is called before the return at the end. That is, the if-statement needs to be: if (ret) break; With this change, I confirmed that all my test cases passed (with all the config debug options this time :). With the change: Reviewed-by: Toshi Kani Tested-by: Toshi Kani Thanks! -Toshi > - res->sibling = new; > + res->sibling = new_res; > + new_res = NULL; > } > > break; > } > > write_unlock(&resource_lock); > + kfree(new_res); > return ret; > } > #endif /* CONFIG_MEMORY_HOTPLUG */ > _ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/