From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id ED24635581F for ; Wed, 17 Dec 2025 15:43:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765986229; cv=none; b=pzxoYWY4K0vMDya2yhCB/p1Wa9ebhE/19mbcjuh/+tvhfhkZLxwqR8cfC3u9TIzcD+X2rJkTpTwOGTQu4IkbliS7kOz77v5yfiicYOg7tnYVO0i5Hsb3IXIkCwTydxOi8pE7WVdT3+BRvbV961uAZBkR0eHg3qSGy35HV+63Da8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765986229; c=relaxed/simple; bh=ghd5jqH+8R9nJNICuiYA0TsQE+isYX/EErE2ZAFaKzc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SS16LQkFW3b0iGB8oqGnsao/nZlFsR9s1t0HPdZZZO87GRKghVQbhEiOtlw9s+oNm5vr/fAYcpY+DWDHjmQVvKnd54BXmWVOaVv0wzgTVeAF1v6+r3lxrClDxyanR5GcJr+PsHYiSjG9GrHOHuezhikj8K+MpXrz1PxqwQpT7lQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2DAC5FEC; Wed, 17 Dec 2025 07:43:39 -0800 (PST) Received: from [10.57.91.77] (unknown [10.57.91.77]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 03E363F73F; Wed, 17 Dec 2025 07:43:42 -0800 (PST) Message-ID: <1beaa7de-4b31-4f19-abee-83872f868e28@arm.com> Date: Wed, 17 Dec 2025 15:43:41 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 Content-Language: en-GB To: Baolin Wang , 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: From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sorry I'm a bit late to the party... 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? > 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. > + 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); > + 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? Thanks, Ryan > /* > * See comment in __ptep_clear_flush_young(); same rationale for > * eliding the trailing DSB applies here. > */ > - addr = ALIGN_DOWN(addr, CONT_PTE_SIZE); > - __flush_tlb_range_nosync(vma->vm_mm, addr, addr + CONT_PTE_SIZE, > + __flush_tlb_range_nosync(vma->vm_mm, start, end, > PAGE_SIZE, true, 3); > } > > return young; > } > -EXPORT_SYMBOL_GPL(contpte_ptep_clear_flush_young); > +EXPORT_SYMBOL_GPL(contpte_clear_flush_young_ptes); > > void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr, > pte_t *ptep, unsigned int nr)