From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757242AbcHDIz4 (ORCPT ); Thu, 4 Aug 2016 04:55:56 -0400 Received: from sender153-mail.zoho.com ([74.201.84.153]:21718 "EHLO sender153-mail.zoho.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754097AbcHDIzy (ORCPT ); Thu, 4 Aug 2016 04:55:54 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=zapps768; d=zoho.com; h=from:subject:to:references:cc:message-id:date:user-agent:mime-version:in-reply-to:content-type; b=MiJxpVqWXzM56iHoPSE4THPytUOM9CNmetSjYNSJIXH7SIN4IDcdKLc3EoOMV6JRz0lAlvUJz5ry eZ1jUsKweBaPJVakAyhbb4ah579xXaFrh4PofE2WIX7MjPNtBWgz From: zijun_hu Subject: Re: [PATCH] mm/vmalloc: fix align value calculation error To: Andrew Morton , tj@kernel.org, hannes@cmpxchg.org References: <57A2F6A3.9080908@zoho.com> Cc: mhocko@kernel.org, minchan@kernel.org, zijun_hu@htc.com, rientjes@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Message-ID: <57A2FE7B.5070505@zoho.com> Date: Thu, 4 Aug 2016 16:36:11 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <57A2F6A3.9080908@zoho.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/04/2016 04:02 PM, zijun_hu wrote: >>>From e40d1066f61394992e0167f259001ae9d2581dc1 Mon Sep 17 00:00:00 2001 > From: zijun_hu > Date: Thu, 4 Aug 2016 14:22:52 +0800 > Subject: [PATCH] mm/vmalloc: fix align value calculation error > > it causes double align requirement for __get_vm_area_node() if parameter > size is power of 2 and VM_IOREMAP is set in parameter flags > > it is fixed by using order_base_2 instead of fls_long() due to lack of > get_count_order() for long parameter > > Signed-off-by: zijun_hu > --- > mm/vmalloc.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 91f44e7..8b17c51 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1357,11 +1357,19 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, > { > struct vmap_area *va; > struct vm_struct *area; > + int ioremap_size_order; > > BUG_ON(in_interrupt()); > - if (flags & VM_IOREMAP) > - align = 1ul << clamp_t(int, fls_long(size), > - PAGE_SHIFT, IOREMAP_MAX_ORDER); > + if (flags & VM_IOREMAP) { > + if (unlikely(size < 2)) > + ioremap_size_order = size; > + else if (unlikely((signed long)size < 0)) > + ioremap_size_order = sizeof(size) * 8; > + else > + ioremap_size_order = order_base_2(size); > + align = 1ul << clamp_t(int, ioremap_size_order, PAGE_SHIFT, > + IOREMAP_MAX_ORDER); > + } > > size = PAGE_ALIGN(size); > if (unlikely(!size)) > another fix approach is shown as follows From: zijun_hu Date: Thu, 4 Aug 2016 14:22:52 +0800 Subject: [PATCH] mm/vmalloc: fix align value calculation error it causes double align requirement for __get_vm_area_node() if parameter size is power of 2 and VM_IOREMAP is set in parameter flags it is fixed by handling the specail case manually due to lack of get_count_order() for long parameter Signed-off-by: zijun_hu --- mm/vmalloc.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 91f44e7..dbbca8a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1357,11 +1357,16 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, { struct vmap_area *va; struct vm_struct *area; + int ioremap_size_order; BUG_ON(in_interrupt()); - if (flags & VM_IOREMAP) - align = 1ul << clamp_t(int, fls_long(size), - PAGE_SHIFT, IOREMAP_MAX_ORDER); + if (flags & VM_IOREMAP) { + ioremap_size_order = fls_long(size); + if (is_power_of_2(size) && size != 1) + ioremap_size_order--; + align = 1ul << clamp_t(int, ioremap_size_order, PAGE_SHIFT, + IOREMAP_MAX_ORDER); + } size = PAGE_ALIGN(size); if (unlikely(!size)) -- 1.9.1