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h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Du4jWa36TFo6ZfukxGs1dMa72ax9sM52+Jj1iJt0U8pryuzeauPPR5wF5v4tCxP7I X+a0P5222OropDvxeqxuV/0vxOrRAh7U67qf3ZLyvpHp2Mvav20APZrCIvnpumDsuZ /CjS03/SIewtNgerFImmjDNzn7gq7MOsH+WiBSO8= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, chrisl@kernel.org, kasong@tencent.com, hughd@google.com, liam@infradead.org Cc: Dev Jain , riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, baolin.wang@linux.alibaba.com, pfalcato@suse.de, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: [PATCH v4 05/12] mm/rmap: batch unmap folios belonging to uffd-wp VMAs Date: Tue, 26 May 2026 12:06:28 +0530 Message-Id: <20260526063635.61721-6-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260526063635.61721-1-dev.jain@arm.com> References: <20260526063635.61721-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: u7kmrgi5qi5n31ig3bfa51dg68xjyrp8 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1E82D40012 X-Rspam-User: X-HE-Tag: 1779777465-102454 X-HE-Meta: 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 sDS3YM7e iaaxBz4KqheXCyaMFTQ4eJL84tKPGeiT7dNjtE57wCmAmnPpRz/saK0cytHCnbrH7GOWlUKKj2UMe2Frkp4CM96Z0hBByCNehF3Qu/MBoEVspvySUNZgUniuBk1K3/01yhJtg8FPtkCUwU7+e06S2VKbqhvm33DtbGAf4aGi/B7KV92vWk+R+O/oEVRdG9iCX/oRpGciI8OOQIOLhjQD7JzqTYtpv8gMwGhn8Jl5px2gosOx4kY/JEK4nmGjrCIva6G6VOvJTM7pbusE= 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_pte_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 cond_install_uffd_wp_ptes, 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. Acked-by: David Hildenbrand (Arm) 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 6a0b43856d6c0..ead031361bc61 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 @@ -2288,7 +2285,7 @@ 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. */ - cond_install_uffd_wp_ptes(vma, address, pvmw.pte, pteval, 1); + cond_install_uffd_wp_ptes(vma, address, pvmw.pte, pteval, nr_pages); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); -- 2.34.1