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 0A15729AB11 for ; Tue, 29 Apr 2025 09:03:13 +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=1745917396; cv=none; b=RiRrQ7RJ4e//64rk+uAaCFw695ikOODypMe3md7AzibuG/NCpqDiDAdGuhnsli/c8v5m2wZlgJIHEPCC1lrWoovGqeqw20WEhJlal7VEKuXF1SY2XbPyBU7vJ3HupQln4n9y0sAlVXH+lKJlCpo3XNUT4tG8m/g8j+mX9Y0hF34= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745917396; c=relaxed/simple; bh=vjNiNlnQNEtIWHSdkehvZhSzUQFapdziJnyclIvRV80=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RugFnyt497PAVe8itoThdqor7fDWwwYb26oJxUn5vhIHhmJrUAddWEhkVtB//9VCgEJYw1bq3RAaGbdZLHd+HY6QZnEUGzG3a/0pVZ4vF0lzzsHxDgKuZsn/GGWZZ01/PZPrlZfvu5vEFjE+Z+t4AmDpPmD8vnQr5dRlrFvz5ro= 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 8995622F8; Tue, 29 Apr 2025 02:03:06 -0700 (PDT) Received: from [10.163.78.253] (unknown [10.163.78.253]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5B9003F673; Tue, 29 Apr 2025 02:03:02 -0700 (PDT) Message-ID: <05c3cd68-0d75-4682-a51c-59307e2b2e78@arm.com> Date: Tue, 29 Apr 2025 14:32:59 +0530 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 0/7] Optimize mprotect for large folios To: Lance Yang , 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 From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 29/04/25 12:36 pm, Lance Yang wrote: > 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 ;) Ah thanks! My bad :( > > 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(-) >> >