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h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DiPGPZeLFr6KMG8ted+Z+UsyEGMycs7zcIFrDVALzOZMUF/rnqvzLNjKXU82OjXNB JnkmmgPephEDbCnUf2tA0uLRAtVr41Ft5dBIAh0gsYDeZ7YiYX+FbrGEj8MKpD29yc 14q33w3pSD8nwfEgSBzmsOWZ5Nvhbj/qkI3UjjyE= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, hughd@google.com, chrisl@kernel.org, kasong@tencent.com Cc: Dev Jain , riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, rppt@kernel.org, surenb@google.com, mhocko@suse.com, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, pfalcato@suse.de, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: [PATCH v3 5/9] mm/rmap: batch unmap folios belonging to uffd-wp VMAs Date: Wed, 6 May 2026 15:15:00 +0530 Message-Id: <20260506094504.2588857-6-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260506094504.2588857-1-dev.jain@arm.com> References: <20260506094504.2588857-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: d3fnu8e9orpuj3cx58wu45nm13qa7yoo X-Rspamd-Queue-Id: CE9FB1A0002 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1778060762-638108 X-HE-Meta: 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 E2/U3gMS TSagpxqKYktHrBhpMod2mhHK1TGcsxI57XZDpUUUu42isCzPV1NkpbFxm9D+E/pko3q16g6jtSSBm41FKl655Bbbs5q85x5jom6eBQNNaE0nCVVILbd0xp+trY2azEK8zZPeR9Bcm854aggGtmzVrO21SLGH0ijI6OEWxc/C6Oy86fa6+csxUC3pSwAPVbvPW41vmVIXs1HMMfgtCt7HQYbwjnILe4WsWxcGDRYF24p8yKzbASnB5EeAv9A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Commit a67fe41e214f ("mm: rmap: support batched unmapping for file large folios") extended batched unmapping for file folios. That also required making install_uffd_wp_ptes_if_needed() support batching, but that was left out for the time being, and correctness was maintained by stopping batching in case the VMA the folio belongs to is marked uffd-wp. Now that we have a batched version called install_uffd_wp_ptes_if_needed, simply call that. folio_unmap_pte_batch() ensures that the original state of the ptes is either all uffd or all non-uffd, so we maintain correctness. If uffd-wp bit is there, we have the following transitions of ptes after unmapping: 1) anon folio: present -> uffd-wp swap 2) file folio: present -> uffd-wp marker We must ensure that these ptes are not reprocessed by the while loop - if the batch length is less than the number of pages in the folio, then we must skip over this batch. The page_vma_mapped_walk API ensures this - check_pte() will return true only if any of [pvmw->pfn, pvmw->pfn + nr_pages) is mapped by the pte. There is no pfn underlying either a uffd-wp swap pte or a uffd-wp marker pte, so check_pte returns false and we keep skipping until we hit a present entry, which is where we want to batch from next. Signed-off-by: Dev Jain --- mm/rmap.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index b17dce752a1ea..25813e3605991 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1965,9 +1965,6 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio, if (pte_unused(pte)) return 1; - if (userfaultfd_wp(vma)) - return 1; - /* * If unmap fails, we need to restore the ptes. To avoid accidentally * upgrading write permissions for ptes that were not originally @@ -2266,7 +2263,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * we may want to replace a none pte with a marker pte if * it's file-backed, so we don't lose the tracking info. */ - install_uffd_wp_ptes_if_needed(vma, address, pvmw.pte, pteval, 1); + install_uffd_wp_ptes_if_needed(vma, address, pvmw.pte, pteval, nr_pages); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); -- 2.34.1