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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8FCA7D68BE3 for ; Thu, 18 Dec 2025 07:15:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=uauTuHRqpfPJlC4EeGuuyBYgKP0qHs1Wgk0vfO6QTvs=; b=bcv6EElnImgrnJsZMF9VBf9kiA 3PS4qqmD+pplb0CfuICF+u7fBznmgo3SufbgbZ8nAVeehpjaRM5IE4jiMmMYNiIMaOFQjvH9bGDms qKvpfd9Ik/ph/AFmZfiGJdMAXNshW5bE39v31Q0m1LOoCa8DKb+o8BrXkl63RbMrhtF5ZC0nepio+ aAkGwAJ94NsrDA9n6uwv2jAJvhABDVUHrRxkQp7zlXilWAg9vdUUXyQvWeuL/6x7oCASoBKONgfjU K3J9v0erXo0HqpaBO8ByW9fTFephmCssVGgf/wEqWwk92MkjgyTzRWPZ91Q/MuCOHT4qQ9TZQ8O2a BpUTvvxw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vW8EU-00000007wjO-2gjH; Thu, 18 Dec 2025 07:15:30 +0000 Received: from out30-110.freemail.mail.aliyun.com ([115.124.30.110]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vW8EP-00000007whn-44Vc for linux-arm-kernel@lists.infradead.org; Thu, 18 Dec 2025 07:15:28 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1766042119; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=uauTuHRqpfPJlC4EeGuuyBYgKP0qHs1Wgk0vfO6QTvs=; b=Z5joIWriMfA9Ui9fXMNOJMahLeYJOE7gP7th9lIMnS+9lkzH9Ln1WX31a9pfg3/7oPlpwK/Of94jK1PNaCAGkMUxEFxAyL7DJtFyIMN5aE2R56F3kbtGaIM4jo4xruxdBcQqfAA10XrOwKX7qXoiNSxjFrI4zhqA+CIV/ClOA4w= Received: from 30.74.144.118(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Wv7ehcK_1766042116 cluster:ay36) by smtp.aliyun-inc.com; Thu, 18 Dec 2025 15:15:17 +0800 Message-ID: <96c0adcc-abfd-4a44-be93-1c6bd7942d6d@linux.alibaba.com> Date: Thu, 18 Dec 2025 15:15:16 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/3] arm64: mm: support batch clearing of the young flag for large folios To: Ryan Roberts , akpm@linux-foundation.org, david@kernel.org, catalin.marinas@arm.com, will@kernel.org Cc: lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, willy@infradead.org, baohua@kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <1beaa7de-4b31-4f19-abee-83872f868e28@arm.com> From: Baolin Wang In-Reply-To: <1beaa7de-4b31-4f19-abee-83872f868e28@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251217_231526_786936_8BAA255E X-CRM114-Status: GOOD ( 23.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2025/12/17 23:43, Ryan Roberts wrote: > Sorry I'm a bit late to the party... Never mind. It's not late and comments are always welcome :) > On 11/12/2025 08:16, Baolin Wang wrote: >> Currently, contpte_ptep_test_and_clear_young() and contpte_ptep_clear_flush_young() >> only clear the young flag and flush TLBs for PTEs within the contiguous range. >> To support batch PTE operations for other sized large folios in the following >> patches, adding a new parameter to specify the number of PTEs. >> >> While we are at it, rename the functions to maintain consistency with other >> contpte_*() functions. >> >> Signed-off-by: Baolin Wang >> --- >> arch/arm64/include/asm/pgtable.h | 12 ++++----- >> arch/arm64/mm/contpte.c | 44 ++++++++++++++++++++++---------- >> 2 files changed, 37 insertions(+), 19 deletions(-) >> >> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h >> index 0944e296dd4a..e03034683156 100644 >> --- a/arch/arm64/include/asm/pgtable.h >> +++ b/arch/arm64/include/asm/pgtable.h >> @@ -1679,10 +1679,10 @@ extern void contpte_clear_full_ptes(struct mm_struct *mm, unsigned long addr, >> extern pte_t contpte_get_and_clear_full_ptes(struct mm_struct *mm, >> unsigned long addr, pte_t *ptep, >> unsigned int nr, int full); >> -extern int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma, >> - unsigned long addr, pte_t *ptep); >> -extern int contpte_ptep_clear_flush_young(struct vm_area_struct *vma, >> - unsigned long addr, pte_t *ptep); >> +extern int contpte_test_and_clear_young_ptes(struct vm_area_struct *vma, >> + unsigned long addr, pte_t *ptep, unsigned int nr); >> +extern int contpte_clear_flush_young_ptes(struct vm_area_struct *vma, >> + unsigned long addr, pte_t *ptep, unsigned int nr); > > The "contpte_" functions are intended to be private to the arm64 arch and should > be exposed via the generic APIs. But I don't see any generic batched API for > this, so you're only actually able to pass CONT_PTES as nr. Perhaps you're > planning to define "test_and_clear_young_ptes()" and "clear_flush_young_ptes()" > in later patches? Right. This is a preparation patch, and will be used in patch 2. >> extern void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr, >> pte_t *ptep, unsigned int nr); >> extern int contpte_ptep_set_access_flags(struct vm_area_struct *vma, >> @@ -1854,7 +1854,7 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, >> if (likely(!pte_valid_cont(orig_pte))) >> return __ptep_test_and_clear_young(vma, addr, ptep); >> >> - return contpte_ptep_test_and_clear_young(vma, addr, ptep); >> + return contpte_test_and_clear_young_ptes(vma, addr, ptep, CONT_PTES); >> } >> >> #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH >> @@ -1866,7 +1866,7 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma, >> if (likely(!pte_valid_cont(orig_pte))) >> return __ptep_clear_flush_young(vma, addr, ptep); >> >> - return contpte_ptep_clear_flush_young(vma, addr, ptep); >> + return contpte_clear_flush_young_ptes(vma, addr, ptep, CONT_PTES); >> } >> >> #define wrprotect_ptes wrprotect_ptes >> diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c >> index c0557945939c..19b122441be3 100644 >> --- a/arch/arm64/mm/contpte.c >> +++ b/arch/arm64/mm/contpte.c >> @@ -488,8 +488,9 @@ pte_t contpte_get_and_clear_full_ptes(struct mm_struct *mm, >> } >> EXPORT_SYMBOL_GPL(contpte_get_and_clear_full_ptes); >> >> -int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma, >> - unsigned long addr, pte_t *ptep) >> +int contpte_test_and_clear_young_ptes(struct vm_area_struct *vma, >> + unsigned long addr, pte_t *ptep, >> + unsigned int nr) >> { >> /* >> * ptep_clear_flush_young() technically requires us to clear the access >> @@ -500,39 +501,56 @@ int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma, >> * having to unfold. >> */ >> >> + unsigned long start = addr; > > Personally I wouldn't bother defining start - just reuse addr. You're > incrementing start in the below loop, so it's more appropriate to call it addr > anyway. OK. >> + unsigned long end = start + nr * PAGE_SIZE; >> int young = 0; >> int i; >> >> - ptep = contpte_align_down(ptep); >> - addr = ALIGN_DOWN(addr, CONT_PTE_SIZE); >> + if (pte_cont(__ptep_get(ptep + nr - 1))) >> + end = ALIGN(end, CONT_PTE_SIZE); >> >> - for (i = 0; i < CONT_PTES; i++, ptep++, addr += PAGE_SIZE) >> - young |= __ptep_test_and_clear_young(vma, addr, ptep); >> + if (pte_cont(__ptep_get(ptep))) { >> + start = ALIGN_DOWN(start, CONT_PTE_SIZE); >> + ptep = contpte_align_down(ptep); >> + } >> + >> + nr = (end - start) / PAGE_SIZE; >> + for (i = 0; i < nr; i++, ptep++, start += PAGE_SIZE) > > Given you're now defining end, perhaps we don't need nr? > > for (; addr != end; ptep++, addr += PAGE_SIZE) > young |= __ptep_test_and_clear_young(vma, addr, ptep); Yes, good point. >> + young |= __ptep_test_and_clear_young(vma, start, ptep); >> >> return young; >> } >> -EXPORT_SYMBOL_GPL(contpte_ptep_test_and_clear_young); >> +EXPORT_SYMBOL_GPL(contpte_test_and_clear_young_ptes); >> >> -int contpte_ptep_clear_flush_young(struct vm_area_struct *vma, >> - unsigned long addr, pte_t *ptep) >> +int contpte_clear_flush_young_ptes(struct vm_area_struct *vma, >> + unsigned long addr, pte_t *ptep, >> + unsigned int nr) >> { >> int young; >> >> - young = contpte_ptep_test_and_clear_young(vma, addr, ptep); >> + young = contpte_test_and_clear_young_ptes(vma, addr, ptep, nr); >> >> if (young) { >> + unsigned long start = addr; >> + unsigned long end = start + nr * PAGE_SIZE; >> + >> + if (pte_cont(__ptep_get(ptep + nr - 1))) >> + end = ALIGN(end, CONT_PTE_SIZE); >> + >> + if (pte_cont(__ptep_get(ptep))) >> + start = ALIGN_DOWN(start, CONT_PTE_SIZE); >> + > > We now have this pattern of expanding contpte blocks up and down in 3 places. > Perhaps create a helper? Sounds reasonable. How about the following helper? static pte_t *contpte_align_addr_ptep(unsigned long *start, unsigned long *end, pte_t *ptep, unsigned int nr) { unsigned long end_addr = *start + nr * PAGE_SIZE; if (pte_cont(__ptep_get(ptep + nr - 1))) *end = ALIGN(end_addr, CONT_PTE_SIZE); if (pte_cont(__ptep_get(ptep))) { *start = ALIGN_DOWN(*start, CONT_PTE_SIZE); ptep = contpte_align_down(ptep); } return ptep; }