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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 2971D100015 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: ip8wfwx8chs9ron81hnb711bwr3m1t73 X-HE-Tag: 1701084532-158300 X-HE-Meta: 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 bX2aqZT+ Vt27V/fRNzPqLtO26VFjSNdjRxEbZ3eCVtZMd1gjpOVQRifPrOzCwEC6Quhp1a6TW9rEFWV74RsY8NU/5isvJcLVqsQ3zYdEwtQ/M88CSX48HhPuneJ5EQqsZCAQZmtvMfkUiqwRoU2A3zOgGjAY9Uaqxxe17BzoNxd6mjrRQ2hDhWCSRgDIeLZwJBRXnsXtF07jtyy0SH42m3LvPWNjegDXxxwVAtooQpbeTJGZF66dUyc83LbVH7x5mnb3jY2Y3socA5CP5jnRvrxYSM7YrpJFs/uJzh5SqeXLqd1hgqwANEh3nvPZhP38OVZFbkDFLNkMEUwzX6vjSyRgbhVP1nQlQAg== 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 27/11/2023 03:41, Barry Song wrote: >> + if ((nr_pages == 1 && vmf_pte_changed(vmf)) || >> + (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); >> goto release; >> } > > Hi Ryan, > what has stopped nr_pages == 1 from using !pte_range_none(vmf->pte, 1) > directly, then the code can become, > + if (!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); > goto release; > } > > for both 1 and > 1 cases? We can get to do_anonymous_page() from 2 routes: - page fault on unallocated memory (pte_none()) - page fault on uffd_wp pte marker In the latter case, we guarrantee that we are only operating on nr_pages == 1 because when uffd is in the picture we need to preserve any uffd state per-pte. It also means we can't just check the pte is none because in this case it is not none, it has a pte marker so we need to check it hasn't changed. I was previously abstracting this in vmf_pte_range_changed() but there were complaints [1] about the semantic being different based on the number of pages, so this was my attempt to make it more understandable. [1] https://lore.kernel.org/linux-mm/a6fa0847-a950-4044-972c-e5dc8cbc7922@arm.com/ Thanks, Ryan > > Thanks > Barry >