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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47CC7C4345F for ; Tue, 16 Apr 2024 16:29:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CB9FD6B0098; Tue, 16 Apr 2024 12:29:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C69D96B0099; Tue, 16 Apr 2024 12:29:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B30FA6B009A; Tue, 16 Apr 2024 12:29:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 94C816B0098 for ; Tue, 16 Apr 2024 12:29:33 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 12E0D1A0BB1 for ; 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imf29.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf29.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1713284971; a=rsa-sha256; cv=none; b=qmbPL5pa2krVfae82DMaR7/G0FdgURqynYI093nPNSdsfYciK4nVk1IxC4sULAwF/Cf9Nv 94QTJn7B6aL/tujIz4gv8o/joQ9eDM/du6ljyBSb/XnBuPfmboiMgM41YgRHNDvX5Xa9Yi jc6RaxmOwr8MSBffqXVu74ZzPSLCIpo= 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 A5629339; Tue, 16 Apr 2024 09:29:58 -0700 (PDT) Received: from [10.1.39.189] (XHFQ2J9959.cambridge.arm.com [10.1.39.189]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 823B43F792; Tue, 16 Apr 2024 09:29:28 -0700 (PDT) Message-ID: <456de31b-221f-4aeb-a2d3-9bb318526417@arm.com> Date: Tue, 16 Apr 2024 17:29:27 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 2/3] mm/arm64: override clear_young_dirty_ptes() batch helper Content-Language: en-GB To: Lance Yang , akpm@linux-foundation.org Cc: david@redhat.com, 21cnbao@gmail.com, mhocko@suse.com, fengwei.yin@intel.com, zokeefe@google.com, shy828301@gmail.com, xiehuan09@gmail.com, wangkefeng.wang@huawei.com, songmuchun@bytedance.com, peterx@redhat.com, minchan@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20240416033457.32154-1-ioworker0@gmail.com> <20240416033457.32154-3-ioworker0@gmail.com> From: Ryan Roberts In-Reply-To: <20240416033457.32154-3-ioworker0@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: zarq9363y93gphhx599ieh4trkqiz7i7 X-Rspamd-Queue-Id: 5F7FD120010 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1713284971-481291 X-HE-Meta: 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 g2BtLdi6 zzRk+whwd7zQLkSRnhYbFXMAvTP+yjTKAroO1Pp6OUACyLGsMK9AJAa6msszl0f8yCT+H7Py/G9dOTPvJn/bfZlu+vW09VAsli4rKp/8+10YmdraSlfBvOsyae5Rx5/J2R/YVebt9K/Z9GqevD6svY6xPav5EMxRmlLE+afflVR3ooppyjT2Qk2oTCvesffR6kxSOYY1BNljf34m//Bddxm5kwkNy5ev61hP3Ky78Yh8qp0AgGMQsou+0tamK2cpglVPgBu9rOaqVX7lzKpjGpoeG4ilKWPA74bqPy607V2J4/PI= 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 16/04/2024 04:34, Lance Yang wrote: > The per-pte get_and_clear/modify/set approach would result in > unfolding/refolding for contpte mappings on arm64. So we need > to override clear_young_dirty_ptes() for arm64 to avoid it. > > Suggested-by: David Hildenbrand > Suggested-by: Barry Song <21cnbao@gmail.com> > Suggested-by: Ryan Roberts > Signed-off-by: Lance Yang Reviewed-by: Ryan Roberts > --- > arch/arm64/include/asm/pgtable.h | 55 ++++++++++++++++++++++++++++++++ > arch/arm64/mm/contpte.c | 29 +++++++++++++++++ > 2 files changed, 84 insertions(+) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index 9fd8613b2db2..1303d30287dc 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -1223,6 +1223,46 @@ static inline void __wrprotect_ptes(struct mm_struct *mm, unsigned long address, > __ptep_set_wrprotect(mm, address, ptep); > } > > +static inline void __clear_young_dirty_pte(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, > + pte_t pte, cydp_t flags) > +{ > + pte_t old_pte; > + > + do { > + old_pte = pte; > + > + if (flags & CYDP_CLEAR_YOUNG) > + pte = pte_mkold(pte); > + if (flags & CYDP_CLEAR_DIRTY) > + pte = pte_mkclean(pte); > + > + pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep), > + pte_val(old_pte), pte_val(pte)); > + } while (pte_val(pte) != pte_val(old_pte)); > +} > + > +static inline void __clear_young_dirty_ptes(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, > + unsigned int nr, cydp_t flags) > +{ > + pte_t pte; > + > + for (;;) { > + pte = __ptep_get(ptep); > + > + if (flags == (CYDP_CLEAR_YOUNG | CYDP_CLEAR_DIRTY)) > + __set_pte(ptep, pte_mkclean(pte_mkold(pte))); > + else > + __clear_young_dirty_pte(vma, addr, ptep, pte, flags); > + > + if (--nr == 0) > + break; > + ptep++; > + addr += PAGE_SIZE; > + } > +} > + > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > #define __HAVE_ARCH_PMDP_SET_WRPROTECT > static inline void pmdp_set_wrprotect(struct mm_struct *mm, > @@ -1379,6 +1419,9 @@ extern void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr, > extern int contpte_ptep_set_access_flags(struct vm_area_struct *vma, > unsigned long addr, pte_t *ptep, > pte_t entry, int dirty); > +extern void contpte_clear_young_dirty_ptes(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, > + unsigned int nr, cydp_t flags); > > static __always_inline void contpte_try_fold(struct mm_struct *mm, > unsigned long addr, pte_t *ptep, pte_t pte) > @@ -1603,6 +1646,17 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma, > return contpte_ptep_set_access_flags(vma, addr, ptep, entry, dirty); > } > > +#define clear_young_dirty_ptes clear_young_dirty_ptes > +static inline void clear_young_dirty_ptes(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, > + unsigned int nr, cydp_t flags) > +{ > + if (likely(nr == 1 && !pte_cont(__ptep_get(ptep)))) > + __clear_young_dirty_ptes(vma, addr, ptep, nr, flags); > + else > + contpte_clear_young_dirty_ptes(vma, addr, ptep, nr, flags); > +} > + > #else /* CONFIG_ARM64_CONTPTE */ > > #define ptep_get __ptep_get > @@ -1622,6 +1676,7 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma, > #define wrprotect_ptes __wrprotect_ptes > #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS > #define ptep_set_access_flags __ptep_set_access_flags > +#define clear_young_dirty_ptes __clear_young_dirty_ptes > > #endif /* CONFIG_ARM64_CONTPTE */ > > diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c > index 1b64b4c3f8bf..9f9486de0004 100644 > --- a/arch/arm64/mm/contpte.c > +++ b/arch/arm64/mm/contpte.c > @@ -361,6 +361,35 @@ void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr, > } > EXPORT_SYMBOL_GPL(contpte_wrprotect_ptes); > > +void contpte_clear_young_dirty_ptes(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, > + unsigned int nr, cydp_t flags) > +{ > + /* > + * We can safely clear access/dirty without needing to unfold from > + * the architectures perspective, even when contpte is set. If the > + * range starts or ends midway through a contpte block, we can just > + * expand to include the full contpte block. While this is not > + * exactly what the core-mm asked for, it tracks access/dirty per > + * folio, not per page. And since we only create a contpte block > + * when it is covered by a single folio, we can get away with > + * clearing access/dirty for the whole block. > + */ > + unsigned long start = addr; > + unsigned long end = start + nr; > + > + 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); > + ptep = contpte_align_down(ptep); > + } > + > + __clear_young_dirty_ptes(vma, start, ptep, end - start, flags); > +} > +EXPORT_SYMBOL_GPL(contpte_clear_young_dirty_ptes); > + > int contpte_ptep_set_access_flags(struct vm_area_struct *vma, > unsigned long addr, pte_t *ptep, > pte_t entry, int dirty)