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b=j8wliFt/RDLD/6uZ0ks42IvRzsIBbj7t0wGRM7ogC3qpzrZ74zNFj1YqP9y0lwYBzuOfSCun2nbCNWQlQQqwUBEid7PucY5LmdMfMyrVG0kWRh6chfKW9lde4uStbbLxxRMfBTOjgm2y593alrWudh0TTwaMi1XWmVw1XvsH3gA= 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-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 2D0E81C000E X-Stat-Signature: 717rfg7drrcxsabrca8n9nh7z9c9oxfh X-HE-Tag: 1766042120-987956 X-HE-Meta: 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 r0TgcbW7 14UlXFn+PE06WGG7dRGjzXxfbRuveu8+/pcVASWoPCvkeAuq7R+Y8hu+hmDFWnKtgJI3RNbzV3zv7OQX6zvJba+pGlGkLt3XDwt1/0ByovA4N4oebfe36Md6Kf/sEbab07jrfaNbhZwc1JpY0Dx1JJEtmc5PspZ5vjp6G1rPutV6QRZNQeSD+eQdczhfd8GVSEmEx2A2ycfl3fem5mWUw2M4uwJAGDoISZDPbAyzyArJ3A1EsDUMMAm2R0vhY5OVdZcyITnvSszdC3DzVcd2XU8yUt1/w3MHvE+Uawwkj5rMELZk= 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: List-Subscribe: List-Unsubscribe: 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; }