From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 85C24274FF0 for ; Tue, 29 Apr 2025 07:06:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745910413; cv=none; b=AmUfKqfaHMCMGhQO5JbFrFgsg9KgIh7m7XXrMVDmzWvfRV4SH2qX4V3NqoRwmiaDH5zFCRokeKGaxDZAxUlwUkHC/LLTxDeAkRsug7oqakChxPUH4l9yrM+GDS/VRJVxZvUfIbmbS3XOEtLq584rNu6HWLj73U+k2SmL4eHeWww= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745910413; c=relaxed/simple; bh=Bwl8OfcRsdcuUAeT2LbTi04Y6tWPstf6LJFl6PdTExc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=dWlfjwp+m8b2OthLiriCRC7H3gc33ik51DjzERMYMbdTVSnkja/XN30p3w2hE7P5/KeOPY5Qx002GGx2BkaDbKZumD99FLp0BEYqSA6k7OVNFnNLsNa4LkE0qmNsqvEPWD7nMhmOYioPZutEET+8RVi62HVI7covR5DMp8ZYE1A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=fVDMhRWN; arc=none smtp.client-ip=91.218.175.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="fVDMhRWN" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1745910407; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=M1HJrQJGWIT9AFf/jcCjNDbRZ0ry2drXdhiftJCR3bw=; b=fVDMhRWNp7xitc5a/aioHm5KvwDVTcs6s0xsh7qTE0whrr/+wD0frft+l6OumMnKYiexUe rTXh6TDb3pL9NMCXnx05kZQq0liV5JyWH8SSE2u22wjLZbbODECgHiSQx3AjUYs0hE48jo aizdjveLyaM61eZSFJEEeDl0jtKZkgk= Date: Tue, 29 Apr 2025 15:06:33 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v2 0/7] Optimize mprotect for large folios To: Dev Jain , akpm@linux-foundation.org Cc: ryan.roberts@arm.com, david@redhat.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, jannh@google.com, anshuman.khandual@arm.com, peterx@redhat.com, joey.gouly@arm.com, ioworker0@gmail.com, baohua@kernel.org, kevin.brodsky@arm.com, quic_zhenhuah@quicinc.com, christophe.leroy@csgroup.eu, yangyicong@hisilicon.com, linux-arm-kernel@lists.infradead.org, namit@vmware.com, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com References: <20250429052336.18912-1-dev.jain@arm.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: <20250429052336.18912-1-dev.jain@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Hey Dev, Hmm... I also hit the same compilation errors: In file included from ./include/linux/kasan.h:37, from ./include/linux/slab.h:260, from ./include/linux/crypto.h:19, from arch/x86/kernel/asm-offsets.c:9: ./include/linux/pgtable.h: In function ‘modify_prot_start_ptes’: ./include/linux/pgtable.h:905:15: error: implicit declaration of function ‘ptep_modify_prot_start’ [-Werror=implicit-function-declaration] 905 | pte = ptep_modify_prot_start(vma, addr, ptep); | ^~~~~~~~~~~~~~~~~~~~~~ ./include/linux/pgtable.h:905:15: error: incompatible types when assigning to type ‘pte_t’ from type ‘int’ ./include/linux/pgtable.h:909:27: error: incompatible types when assigning to type ‘pte_t’ from type ‘int’ 909 | tmp_pte = ptep_modify_prot_start(vma, addr, ptep); | ^~~~~~~~~~~~~~~~~~~~~~ ./include/linux/pgtable.h: In function ‘modify_prot_commit_ptes’: ./include/linux/pgtable.h:925:17: error: implicit declaration of function ‘ptep_modify_prot_commit’ [-Werror=implicit-function-declaration] 925 | ptep_modify_prot_commit(vma, addr, ptep, old_pte, pte); | ^~~~~~~~~~~~~~~~~~~~~~~ ./include/linux/pgtable.h: At top level: ./include/linux/pgtable.h:1360:21: error: conflicting types for ‘ptep_modify_prot_start’; have ‘pte_t(struct vm_area_struct *, long unsigned int, pte_t *)’ 1360 | static inline pte_t ptep_modify_prot_start(struct vm_area_struct *vma, | ^~~~~~~~~~~~~~~~~~~~~~ ./include/linux/pgtable.h:905:15: note: previous implicit declaration of ‘ptep_modify_prot_start’ with type ‘int()’ 905 | pte = ptep_modify_prot_start(vma, addr, ptep); | ^~~~~~~~~~~~~~~~~~~~~~ ./include/linux/pgtable.h:1371:20: warning: conflicting types for ‘ptep_modify_prot_commit’; have ‘void(struct vm_area_struct *, long unsigned int, pte_t *, pte_t, pte_t)’ 1371 | static inline void ptep_modify_prot_commit(struct vm_area_struct *vma, | ^~~~~~~~~~~~~~~~~~~~~~~ ./include/linux/pgtable.h:1371:20: error: static declaration of ‘ptep_modify_prot_commit’ follows non-static declaration ./include/linux/pgtable.h:925:17: note: previous implicit declaration of ‘ptep_modify_prot_commit’ with type ‘void(struct vm_area_struct *, long unsigned int, pte_t *, pte_t, pte_t)’ 925 | ptep_modify_prot_commit(vma, addr, ptep, old_pte, pte); | ^~~~~~~~~~~~~~~~~~~~~~~ CC /home/runner/work/mm-test-robot/mm-test-robot/linux/tools/objtool/libstring.o CC /home/runner/work/mm-test-robot/mm-test-robot/linux/tools/objtool/libctype.o CC /home/runner/work/mm-test-robot/mm-test-robot/linux/tools/objtool/str_error_r.o CC /home/runner/work/mm-test-robot/mm-test-robot/linux/tools/objtool/librbtree.o cc1: some warnings being treated as errors make[2]: *** [scripts/Makefile.build:98: arch/x86/kernel/asm-offsets.s] Error 1 make[1]: *** [/home/runner/work/mm-test-robot/mm-test-robot/linux/Makefile:1280: prepare0] Error 2 make[1]: *** Waiting for unfinished jobs.... LD /home/runner/work/mm-test-robot/mm-test-robot/linux/tools/objtool/objtool-in.o LINK /home/runner/work/mm-test-robot/mm-test-robot/linux/tools/objtool/objtool make: *** [Makefile:248: __sub-make] Error 2 Well, modify_prot_start_ptes() calls ptep_modify_prot_start(), but x86 does not define __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION. To avoid implicit declaration errors, the architecture-independent ptep_modify_prot_start() must be defined before modify_prot_start_ptes(). With the changes below, things work correctly now ;) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 10cdb87ccecf..d9d6c49bb914 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -895,44 +895,6 @@ static inline void wrprotect_ptes(struct mm_struct *mm, unsigned long addr, } #endif -/* See the comment for ptep_modify_prot_start */ -#ifndef modify_prot_start_ptes -static inline pte_t modify_prot_start_ptes(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep, unsigned int nr) -{ - pte_t pte, tmp_pte; - - pte = ptep_modify_prot_start(vma, addr, ptep); - while (--nr) { - ptep++; - addr += PAGE_SIZE; - tmp_pte = ptep_modify_prot_start(vma, addr, ptep); - if (pte_dirty(tmp_pte)) - pte = pte_mkdirty(pte); - if (pte_young(tmp_pte)) - pte = pte_mkyoung(pte); - } - return pte; -} -#endif - -/* See the comment for ptep_modify_prot_commit */ -#ifndef modify_prot_commit_ptes -static inline void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr, - pte_t *ptep, pte_t old_pte, pte_t pte, unsigned int nr) -{ - for (;;) { - ptep_modify_prot_commit(vma, addr, ptep, old_pte, pte); - if (--nr == 0) - break; - ptep++; - addr += PAGE_SIZE; - old_pte = pte_next_pfn(old_pte); - pte = pte_next_pfn(pte); - } -} -#endif - /* * On some architectures hardware does not set page access bit when accessing * memory page, it is responsibility of software setting this bit. It brings @@ -1375,6 +1337,45 @@ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma, __ptep_modify_prot_commit(vma, addr, ptep, pte); } #endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */ + +/* See the comment for ptep_modify_prot_start */ +#ifndef modify_prot_start_ptes +static inline pte_t modify_prot_start_ptes(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, unsigned int nr) +{ + pte_t pte, tmp_pte; + + pte = ptep_modify_prot_start(vma, addr, ptep); + while (--nr) { + ptep++; + addr += PAGE_SIZE; + tmp_pte = ptep_modify_prot_start(vma, addr, ptep); + if (pte_dirty(tmp_pte)) + pte = pte_mkdirty(pte); + if (pte_young(tmp_pte)) + pte = pte_mkyoung(pte); + } + return pte; +} +#endif + +/* See the comment for ptep_modify_prot_commit */ +#ifndef modify_prot_commit_ptes +static inline void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr, + pte_t *ptep, pte_t old_pte, pte_t pte, unsigned int nr) +{ + for (;;) { + ptep_modify_prot_commit(vma, addr, ptep, old_pte, pte); + if (--nr == 0) + break; + ptep++; + addr += PAGE_SIZE; + old_pte = pte_next_pfn(old_pte); + pte = pte_next_pfn(pte); + } +} +#endif + #endif /* CONFIG_MMU */ /* -- Thanks, Lance On 2025/4/29 13:23, Dev Jain wrote: > This patchset optimizes the mprotect() system call for large folios > by PTE-batching. > > We use the following test cases to measure performance, mprotect()'ing > the mapped memory to read-only then read-write 40 times: > > Test case 1: Mapping 1G of memory, touching it to get PMD-THPs, then > pte-mapping those THPs > Test case 2: Mapping 1G of memory with 64K mTHPs > Test case 3: Mapping 1G of memory with 4K pages > > Average execution time on arm64, Apple M3: > Before the patchset: > T1: 7.9 seconds T2: 7.9 seconds T3: 4.2 seconds > > After the patchset: > T1: 2.1 seconds T2: 2.2 seconds T3: 4.2 seconds > > Observing T1/T2 and T3 before the patchset, we also remove the regression > introduced by ptep_get() on a contpte block. And, for large folios we get > an almost 74% performance improvement. > > v1->v2: > - Rebase onto mm-unstable (6ebffe676fcf: util_macros.h: make the header more resilient) > - Abridge the anon-exclusive condition (Lance Yang) > > Dev Jain (7): > mm: Refactor code in mprotect > mm: Optimize mprotect() by batch-skipping PTEs > mm: Add batched versions of ptep_modify_prot_start/commit > arm64: Add batched version of ptep_modify_prot_start > arm64: Add batched version of ptep_modify_prot_commit > mm: Batch around can_change_pte_writable() > mm: Optimize mprotect() through PTE-batching > > arch/arm64/include/asm/pgtable.h | 10 ++ > arch/arm64/mm/mmu.c | 21 +++- > include/linux/mm.h | 4 +- > include/linux/pgtable.h | 42 ++++++++ > mm/gup.c | 2 +- > mm/huge_memory.c | 4 +- > mm/memory.c | 6 +- > mm/mprotect.c | 165 ++++++++++++++++++++----------- > mm/pgtable-generic.c | 16 ++- > 9 files changed, 198 insertions(+), 72 deletions(-) >