From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-124.freemail.mail.aliyun.com (out30-124.freemail.mail.aliyun.com [115.124.30.124]) (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 6540CC147 for ; Thu, 13 Jun 2024 00:51:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718239916; cv=none; b=k+vIN5lgtDQSf766DLiWTnqQa9v8ekCRaSISOTatep6deu7F+Ln7Nym+w74dc7itVD0cm46Uo7558CMSD0KoeCjBZEpQjrdw9nqR24fcDEaqETWE4KA+TO2gkP8sPTt6yJcogWhfFHWUh+ETGPD3pXZSAZzK78n+R2tFw/cANtk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718239916; c=relaxed/simple; bh=SHoMcIdISwy0muoLftFNdJNW1Crs9VgbH4hEZTuX9Es=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RK8I33VWZPG6QGKs1EFekit7rzGU+3rX1erLfH2/eBXqgjcLdzUgtq5oq/X/z2MdUWGVQvZnNbdtq2vWFHw+dKOVgh1k9LRvonY269oQ99+NwE9d5QUL8kuLHNOdVysdiIMT03ejCgNtB59m0OtFiYdC+kjVUxJL0z+lmf1TzFc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=px9BvqIl; arc=none smtp.client-ip=115.124.30.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="px9BvqIl" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1718239906; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=HPjLzQBCigEVLIfXbDL0xmW8b3HFx8AMly+LLTrutZo=; b=px9BvqIldH4WACJnXdhtq9C0YDemf8u4KOJEuCOeEmhwEOGh5GiqY9U9jipAlqC9Sm5xrGeCX3YGXcWmAuBueVtEeQk+oIlMhlHEO0k+B0zvjk+ws9yNF60jQq/mKY4u6CY/7LU6swkMEv4LHppC7al9EIs8zEeYpJ2yOe5WkQM= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R581e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033022160150;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=15;SR=0;TI=SMTPD_---0W8M6ggj_1718239904; Received: from 30.97.56.57(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0W8M6ggj_1718239904) by smtp.aliyun-inc.com; Thu, 13 Jun 2024 08:51:45 +0800 Message-ID: <86e8c75b-1717-4335-9a1f-c663192dbf84@linux.alibaba.com> Date: Thu, 13 Jun 2024 08:51:43 +0800 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 v5 1/6] mm: memory: extend finish_fault() to support large folio To: Kefeng Wang , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, david@redhat.com, ying.huang@intel.com, 21cnbao@gmail.com, ryan.roberts@arm.com, shy828301@gmail.com, ziy@nvidia.com, ioworker0@gmail.com, da.gomez@samsung.com, p.raghav@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <3a190892355989d42f59cf9f2f98b94694b0d24d.1718090413.git.baolin.wang@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/6/12 21:40, Kefeng Wang wrote: > > > On 2024/6/11 18:11, Baolin Wang wrote: >> Add large folio mapping establishment support for finish_fault() as a >> preparation, to support multi-size THP allocation of anonymous shmem >> pages >> in the following patches. >> >> Keep the same behavior (per-page fault) for non-anon shmem to avoid >> inflating >> the RSS unintentionally, and we can discuss what size of mapping to build >> when extending mTHP to control non-anon shmem in the future. >> >> Signed-off-by: Baolin Wang >> --- >>   mm/memory.c | 57 +++++++++++++++++++++++++++++++++++++++++++---------- >>   1 file changed, 47 insertions(+), 10 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index eef4e482c0c2..72775ee99ff3 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -4831,9 +4831,12 @@ vm_fault_t finish_fault(struct vm_fault *vmf) >>   { >>       struct vm_area_struct *vma = vmf->vma; >>       struct page *page; >> +    struct folio *folio; >>       vm_fault_t ret; >>       bool is_cow = (vmf->flags & FAULT_FLAG_WRITE) && >>                 !(vma->vm_flags & VM_SHARED); >> +    int type, nr_pages; >> +    unsigned long addr = vmf->address; >>       /* Did we COW the page? */ >>       if (is_cow) >> @@ -4864,24 +4867,58 @@ vm_fault_t finish_fault(struct vm_fault *vmf) >>               return VM_FAULT_OOM; >>       } >> +    folio = page_folio(page); >> +    nr_pages = folio_nr_pages(folio); >> + >> +    /* >> +     * Using per-page fault to maintain the uffd semantics, and same >> +     * approach also applies to non-anonymous-shmem faults to avoid >> +     * inflating the RSS of the process. >> +     */ >> +    if (!vma_is_anon_shmem(vma) || unlikely(userfaultfd_armed(vma))) { >> +        nr_pages = 1; >> +    } else if (nr_pages > 1) { >> +        pgoff_t idx = folio_page_idx(folio, page); >> +        /* The page offset of vmf->address within the VMA. */ >> +        pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff; >> + >                         vma->vm_pgoff > >> +        /* >> +         * Fallback to per-page fault in case the folio size in page >> +         * cache beyond the VMA limits. >> +         */ >> +        if (unlikely(vma_off < idx || >> +                 vma_off + (nr_pages - idx) > vma_pages(vma))) { >> +            nr_pages = 1; >> +        } else { >> +            /* Now we can set mappings for the whole large folio. */ >> +            addr = vmf->address - idx * PAGE_SIZE; > >             addr -= idx * PAGE_SIZE; > >> +            page = &folio->page; >> +        } >> +    } >> + >>       vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, >> -                      vmf->address, &vmf->ptl); >> +                       addr, &vmf->ptl); > > no newline now, > >>       if (!vmf->pte) >>           return VM_FAULT_NOPAGE; >>       /* Re-check under ptl */ >> -    if (likely(!vmf_pte_changed(vmf))) { >> -        struct folio *folio = page_folio(page); >> -        int type = is_cow ? MM_ANONPAGES : mm_counter_file(folio); >> - >> -        set_pte_range(vmf, folio, page, 1, vmf->address); >> -        add_mm_counter(vma->vm_mm, type, 1); >> -        ret = 0; >> -    } else { >> -        update_mmu_tlb(vma, vmf->address, vmf->pte); >> +    if (nr_pages == 1 && unlikely(vmf_pte_changed(vmf))) { >> +        update_mmu_tlb(vma, addr, vmf->pte); >> +        ret = VM_FAULT_NOPAGE; >> +        goto unlock; >> +    } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) { >> +        update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); >>           ret = VM_FAULT_NOPAGE; >> +        goto unlock; >>       } > > We may add a vmf_pte_range_changed(), but separate it. > > Some very small nits, up to you, > > Reviewed-by: Kefeng Wang Thanks for reviewing. If a new version is needed, then I will clean up these coding style issues.