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a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784114352; bh=+o9DpSGseXucY8pTcFbS+W9IBHMvf3AT4jdAayQBJ8o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cMFHUiaeqiLmMlN8BYlKnh6OjgLR9tKyb3ltisY+8hUHTgVbih7101lm/gflcV05s aK+QLl9e+84ArIvxO/iHsUkLoj8mfp9CmE7xTuFSSUpzMRuCkkprSSvhYSYcCuxIMl yoBAn5gFAkv7F+upQWY0lmCysJeHP6wuXfi+kueM= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: Dev Jain , liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, riel@surriel.com, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: [PATCH 3/3] mm/rmap: batch unmap file folios belonging to uffd-wp VMAs Date: Wed, 15 Jul 2026 11:18:36 +0000 Message-ID: <20260715111839.1667914-4-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260715111839.1667914-1-dev.jain@arm.com> References: <20260715111839.1667914-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D0EC6C0006 X-Stat-Signature: 4u4zwnmexx59k5mgs3pfcd9mu5ts4df7 X-HE-Tag: 1784114352-745454 X-HE-Meta: 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 os7HFCya wrAu+PKSS/ckn/PlLuOzPk6J1cFmxCjyXOV3sC5MQ5mQ5LuhjsGdebFiq2Xl2IvnZPuAICcGRV+io0YiPMflE5wbplynChf/D0j316dHDKYwbOKkfT9WAZ6+wZaKlb293GS1gW+I3z6xRoUoAT1P/ddKLDx7XBfiIV1GCZPi9MwdXuAkn1GjaV3EuqfL5u09cz1j3B+o/hPAF5RKHUcqUpFeltu8/PqyPtCYlWY7YuENe66uNmX0v2J9h/fy+mySm8dd14beXg5ZXAha0EhTfgc23u7ra4ALb5KTvMDr2AcH72ZE= 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, for a 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 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. Note that for the uffd-rwp case, we already do not make a uffd marker in cond_install_uffd_wp_ptes. Signed-off-by: Dev Jain --- Dropped David's ACK due to the uffd-rwp changes. mm/rmap.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 2f938d0ac6953..ac88673600fa0 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_protected(vma)) - return 1; - /* * If unmap fails, we need to restore the ptes. To avoid accidentally * upgrading write permissions for ptes that were not originally @@ -2345,7 +2342,8 @@ 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); -- 2.43.0