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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 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 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: EE3F01C0009 X-Stat-Signature: u3ik9dcockr5cz4z8we6bfm5enytd6io X-HE-Tag: 1717401884-237303 X-HE-Meta: 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 QYLkrHF3 HrawFqXCIf+to3mLdvY9f+1tcoiN0lAE13KBojkW3CQU/UM9OKN2vnuwF3vbEsWfZPcOzRqgu+JZs6dx1BjiP8YGaHv1chqcTsalsuw926rP/3WkiWR1iGMjOw7aRb+F4eCNW2vCF3ZaLWmJ5gLIREZrennNDV109e00Ts9nEljMJe669OeQpiBRmpfjQ+D+VEMtY20+6AwAAX7AG0pJvPjv9Hm8P2R5ffMpzx5f2joQv9ZlBdEmW87hbUjjb2+mjViRbTfpKjoB5CjMaJTy6hjoXAaYfua6zav9shny4RZpoPeQCwQIXdGcjk9LKToxabDCTZrOMiOssK08S72Cb66Tj9zjvZ934ly2lkUsvW6QrRCr4Fjxt2LB2p/EA6eknw6Hl1Mh5OI3pSMJQ3ZaSLdrpjMG7yLbrnU38a8fV0KMf2Zg2E2jsmv9HvTA4LmBPuQatb+OlvC1Xkb8BJOjx0sWHzPjcCVH0OAp3+X39hJNtpoRpp6AVfZDRBZ/ZPh+G2r4d 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 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.