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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 2A4D2C43331 for ; Wed, 1 Apr 2020 08:55:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0681520784 for ; Wed, 1 Apr 2020 08:55:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731807AbgDAIzG (ORCPT ); Wed, 1 Apr 2020 04:55:06 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:41710 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726536AbgDAIzF (ORCPT ); Wed, 1 Apr 2020 04:55:05 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 3CB9F4174694B46C4C6F; Wed, 1 Apr 2020 16:51:25 +0800 (CST) Received: from [127.0.0.1] (10.173.220.25) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.487.0; Wed, 1 Apr 2020 16:51:17 +0800 Subject: Re: [RFC PATCH v5 4/8] mm: tlb: Pass struct mmu_gather to flush_pmd_tlb_range To: Peter Zijlstra CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20200331142927.1237-1-yezhenyu2@huawei.com> <20200331142927.1237-5-yezhenyu2@huawei.com> <20200331151331.GS20730@hirez.programming.kicks-ass.net> From: Zhenyu Ye Message-ID: Date: Wed, 1 Apr 2020 16:51:15 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20200331151331.GS20730@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.220.25] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, On 2020/3/31 23:13, Peter Zijlstra wrote: > On Tue, Mar 31, 2020 at 10:29:23PM +0800, Zhenyu Ye wrote: >> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h >> index e2e2bef07dd2..32d4661e5a56 100644 >> --- a/include/asm-generic/pgtable.h >> +++ b/include/asm-generic/pgtable.h >> @@ -1160,10 +1160,10 @@ static inline int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) >> * invalidate the entire TLB which is not desitable. >> * e.g. see arch/arc: flush_pmd_tlb_range >> */ >> -#define flush_pmd_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) >> +#define flush_pmd_tlb_range(tlb, vma, addr, end) flush_tlb_range(vma, addr, end) >> #define flush_pud_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) >> #else >> -#define flush_pmd_tlb_range(vma, addr, end) BUILD_BUG() >> +#define flush_pmd_tlb_range(tlb, vma, addr, end) BUILD_BUG() >> #define flush_pud_tlb_range(vma, addr, end) BUILD_BUG() >> #endif >> #endif >> diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c >> index 3d7c01e76efc..96c9cf77bfb5 100644 >> --- a/mm/pgtable-generic.c >> +++ b/mm/pgtable-generic.c >> @@ -109,8 +109,14 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, >> int changed = !pmd_same(*pmdp, entry); >> VM_BUG_ON(address & ~HPAGE_PMD_MASK); >> if (changed) { >> + struct mmu_gather tlb; >> + unsigned long tlb_start = address; >> + unsigned long tlb_end = address + HPAGE_PMD_SIZE; >> set_pmd_at(vma->vm_mm, address, pmdp, entry); >> - flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); >> + tlb_gather_mmu(&tlb, vma->vm_mm, tlb_start, tlb_end); >> + tlb.cleared_pmds = 1; >> + flush_pmd_tlb_range(&tlb, vma, tlb_start, tlb_end); >> + tlb_finish_mmu(&tlb, tlb_start, tlb_end); >> } >> return changed; >> } > > This is madness. Please, carefully consider what you just wrote and what > it will do in the generic case. > > Instead of trying to retro-fit flush_*tlb_range() to take an mmu_gather > parameter, please replace them out-right. > I'm sorry that I'm not sure what "replace them out-right" means. Do you mean that I should define flush_*_tlb_range like this? #define flush_pmd_tlb_range(vma, addr, end) \ do { \ struct mmu_gather tlb; \ tlb_gather_mmu(&tlb, (vma)->vm_mm, addr, end); \ tlba.cleared_pmds = 1; \ flush_tlb_range(&tlb, vma, addr, end); \ tlb_finish_mmu(&tlb, addr, end); \ } while (0) Thanks, Zhenyu