From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (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 50DE3487BF for ; Mon, 3 Jun 2024 08:04:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717401887; cv=none; b=unh1tYO9aoN1JFJNhamS9AQRjkX208lRJ11uGR8SpHT1LKJO4Eak40YGowEcIMErOLDdId+FlZRZ9ipsew/2AXO9cpF5MRqUwScEi59yTVRjSmO0lEJpKipNzGfEytlx+FoDFyNy983b3r1dRmVfccVXNyfiD5l9JbIkng5z0ck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717401887; c=relaxed/simple; bh=JhG7fTxqtLhhNG58bB7gakwsBxU8x6j5V9O91Y38mmY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SPY+XinfljFJxtsQC9EpDUKFRVgsKzB5vHBiYzktzQGpif5Ocew+go3ep8hnEe1ioCvRvl/SZxuz70lzynRZSlguS2ezTcRss6ELp3cwgEPYrMNM28wLpn6RHX/+Jxf5iHlNhBG2EtrF9eWbxv/bUQBq9LIeuQE4F11b2hkX6TI= 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=Jrc3Naue; arc=none smtp.client-ip=115.124.30.130 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="Jrc3Naue" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1717401881; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=o+t7UAkpsXwsI9xsAwJFZS/iROqWU8NNbxxJU91Kwsk=; b=Jrc3Naue58w0R/XScmaiX+gVr0vPDDqX0eVN3PROprLZ6NF4NhyGtf0lsaRCkFZDET8FV79q8BVGvd6ugXEY36ZJl4MCI/qULLaThXmxalfKGo5Sg5g2wCzaYGMT6BJWiWa7/fYnJDrcl2klhgR9wEY3LHCTKimrQnWi64s5Z7Q= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037067113;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=16;SR=0;TI=SMTPD_---0W7kFySD_1717401878; Received: from 30.97.56.74(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0W7kFySD_1717401878) by smtp.aliyun-inc.com; Mon, 03 Jun 2024 16:04:39 +0800 Message-ID: <2ce6d815-541d-497c-8eba-3d5099e8dcd5@linux.alibaba.com> Date: Mon, 3 Jun 2024 16:04:38 +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 v3 1/6] mm: memory: extend finish_fault() to support large folio To: Lance Yang Cc: akpm@linux-foundation.org, hughd@google.com, willy@infradead.org, david@redhat.com, wangkefeng.wang@huawei.com, ying.huang@intel.com, 21cnbao@gmail.com, ryan.roberts@arm.com, shy828301@gmail.com, ziy@nvidia.com, da.gomez@samsung.com, p.raghav@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Bang Li References: From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/6/3 12:44, Lance Yang wrote: > On Thu, May 30, 2024 at 10:04 AM 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. >> >> Signed-off-by: Baolin Wang >> --- >> mm/memory.c | 58 ++++++++++++++++++++++++++++++++++++++++++++--------- >> 1 file changed, 48 insertions(+), 10 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index eef4e482c0c2..435187ff7ea4 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, i; >> + unsigned long addr = vmf->address; >> >> /* Did we COW the page? */ >> if (is_cow) >> @@ -4864,24 +4867,59 @@ 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; >> + >> + /* >> + * 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; >> + page = &folio->page; >> + } >> + } >> + >> vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, >> - vmf->address, &vmf->ptl); >> + addr, &vmf->ptl); >> 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)) { >> + for (i = 0; i < nr_pages; i++) >> + update_mmu_tlb(vma, addr + PAGE_SIZE * i, vmf->pte + i); > > Just a friendly reminder: Bang has added the update_mmu_tlb_range()[1] batch > function to update TLB in batches, so we can use it instead of the > update_mmu_tlb() > loop. > > [1] https://lore.kernel.org/linux-mm/20240522061204.117421-1-libang.li@antgroup.com/ Good point, I will use the new helper instead.