From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0E9BC433DF for ; Sat, 16 May 2020 09:43:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7175520728 for ; Sat, 16 May 2020 09:43:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7175520728 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1873A8E0003; Sat, 16 May 2020 05:43:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 138688E0001; Sat, 16 May 2020 05:43:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 025CA8E0003; Sat, 16 May 2020 05:43:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0171.hostedemail.com [216.40.44.171]) by kanga.kvack.org (Postfix) with ESMTP id DB7368E0001 for ; Sat, 16 May 2020 05:43:22 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 951FE181AEF1A for ; Sat, 16 May 2020 09:43:22 +0000 (UTC) X-FDA: 76822094244.26.nest35_1d4c366d1742f X-HE-Tag: nest35_1d4c366d1742f X-Filterd-Recvd-Size: 4908 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Sat, 16 May 2020 09:43:20 +0000 (UTC) Received: from [10.20.42.25] (unknown [10.20.42.25]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9Dxf9+ftb9eyGs1AA--.4S3; Sat, 16 May 2020 17:42:56 +0800 (CST) Subject: Re: [PATCH 2/3] mm/memory.c: Update local TLB if PTE entry exists To: Andrew Morton References: <1589515809-32422-1-git-send-email-maobibo@loongson.cn> <1589515809-32422-2-git-send-email-maobibo@loongson.cn> <20200515134046.cf107c6a13b9604c46ad71b8@linux-foundation.org> Cc: Thomas Bogendoerfer , Jiaxun Yang , Huacai Chen , Paul Burton , Dmitry Korotin , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Stafford Horne , Steven Price , Anshuman Khandual , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, Mike Rapoport , Sergei Shtylyov , "Maciej W. Rozycki" , linux-mm@kvack.org From: maobibo Message-ID: <61ebeb0a-89cf-834f-1d20-765a2ab43161@loongson.cn> Date: Sat, 16 May 2020 17:42:55 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20200515134046.cf107c6a13b9604c46ad71b8@linux-foundation.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-CM-TRANSID:AQAAf9Dxf9+ftb9eyGs1AA--.4S3 X-Coremail-Antispam: 1UD129KBjvJXoWxJryxGry5Ww47Cr1xXr4DCFg_yoW8CFy7pr 9aka9FqFs7tw18Wr4xXr1qqr18Z342qFy5C34fta4Yk3sFqrs5tFWrGw4F9rW5Zr1fuF4q ya1jgr17Zan7ZFJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9mb7Iv0xC_Kw4lb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rw A2F7IY1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xII jxv20xvEc7CjxVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwV C2z280aVCY1x0267AKxVWxJr0_GcWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xv F2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r 4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvEwIxGrwACI402YVCY1x02628vn2kIc2xK xwCYjI0SjxkI62AI1cAE67vIY487MxkIecxEwVCm-wCF04k20xvY0x0EwIxGrwCFx2IqxV CFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r10 6r1rMI8E67AF67kF1VAFwI0_GFv_WrylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxV WUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG 6rWUJVWrZr1UMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr 0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07b0NVkUUUUU= X-CM-SenderInfo: xpdruxter6z05rqj20fqof0/ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 05/16/2020 04:40 AM, Andrew Morton wrote: > On Fri, 15 May 2020 12:10:08 +0800 Bibo Mao wrote: > >> If there are two threads hitting page fault at the same page, >> one thread updates PTE entry and local TLB, the other can >> update local tlb also, rather than give up and do page fault >> again. >> >> ... >> >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -1770,8 +1770,8 @@ static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, >> } >> entry = pte_mkyoung(*pte); >> entry = maybe_mkwrite(pte_mkdirty(entry), vma); >> - if (ptep_set_access_flags(vma, addr, pte, entry, 1)) >> - update_mmu_cache(vma, addr, pte); >> + ptep_set_access_flags(vma, addr, pte, entry, 1); >> + update_mmu_cache(vma, addr, pte); > > Presumably these changes mean that other architectures will run > update_mmu_cache() more frequently than they used to. How much more > frequently, and what will be the impact of this change? (Please fully > explain all this in the changelog). > It is only useful for those architects where software can update tlb, if the function update_mmu_cache is used for other reason, it will bring out somewhat impact, and I will explain it in the changelog. >> } >> goto out_unlock; >> } >> >> ... >> >> @@ -2463,7 +2462,8 @@ static inline bool cow_user_page(struct page *dst, struct page *src, >> vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); >> locked = true; >> if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) { >> - /* The PTE changed under us. Retry page fault. */ >> + /* The PTE changed under us, update local tlb */ >> + pdate_mmu_cache(vma, addr, vmf->pte); > > Missing a 'u' there. Which tells me this patch isn't the one which you > tested! > Sorry about it, I will refresh the patch and add modification about this obvious typo regards bibo, mao >> ret = false; >> goto pte_unlock; >> } >> >> ... >>