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h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B8Zxi1oowJQksrIiPBubX8jrt3yniQITzN3UZ8rLvHMLHv/Ien8ryoISTvpCoiy6I qWpA8/CW72pBeVLfZYBV9iNeewvz+tzYciTIn+MDm3gV85bUmGJExuFSPQIKV6ow5V 7Q80cSOMa3itWQ//epcQbaltosKJVSg8wXCNYYK4= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, hughd@google.com, chrisl@kernel.org Cc: ljs@kernel.org, Liam.Howlett@oracle.com, 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, riel@surriel.com, harry@kernel.org, jannh@google.com, pfalcato@suse.de, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, Dev Jain Subject: [PATCH v2 8/9] mm/rmap: Add batched version of folio_try_share_anon_rmap_pte Date: Fri, 10 Apr 2026 16:02:03 +0530 Message-Id: <20260410103204.120409-9-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260410103204.120409-1-dev.jain@arm.com> References: <20260410103204.120409-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 832DD40013 X-Stat-Signature: 1dtiao7dhui8k5gm96u1hhyx67qpemw9 X-Rspamd-Server: rspam06 X-HE-Tag: 1775817211-224553 X-HE-Meta: U2FsdGVkX1+DArfekCLzvcdHDmnJ0+TbrX5DqRaLzPppCXSQQUJV+anksYyfSRI8mP71kfvuGuNrh/Zk8sdDdQKkrg2qJs7Hfu880aY7OWkXp6gF2jPvMW1Go0UZ0XODUezGKhH2j6Hmh0n7erxq1i/DaDnZGQGjxHt4gWibsW2Cb1yWq91zgcQwWW0MxHKmFBClIBUqCtm8kPmEp/CJSJ5HKvxcdJT5uwiIe0JeES6BsKa7xFAoW4BNWtLerD8otZW4GIV0NXVd5Hd47DZ0248ut8VBGRQH+a2SabpXzeqMshSb9f33Q9LIOG8JGtPFo1aZASzjaNO7P/oOFaSlgsDk76KwIgKTaV5j2LmDmDH5sV+mt2+yuPUSRXJBRrpZP/8XM5Y6nsq719CW1n9AowAJtIvHD2ZRurDJA7mx8n+8XM3OPrqgGze/4UBekJY11MwgrnBvH+cLUG9tUApk+tVJYuFNiDDYM24ydBcVNdMO6W44cqcdEKOxk6RwZtj7CKC2idVDXDeqOH0LhtJE4L64o6Vwk8aLCGdqEmRBupTK8Z1UT3NE4tBGDKsFOigU3mNw49Lo6aeeHEpSbqt/w1gnbmlNetWgspLZxaY2ZQFYci5B+T0ZfL/cgse1Q92CgZSSAbPQhaLFRJdMFn7X7HgNvZ0BpaUc74lx06c7bTN+zpM852ES+uiq4rDLdkKklT7f/J8+p6gU5lDV07J922Q7QdBQ5J6iCxjAyq1IuieKsD4vAuzzRE2UnlciI9deGu6+JMaCHEHgikrGxcYfZ7uJIyiMyUbZuLP+gueCIR4WSM/VZ0uV7UgUydvJYoVPeWVSMwoGR7PVmsGWs/XXoXDLSkk7WmnXwiGmyHG2Bb3BduA5jgHDOrxg5RzkYxGYFPDLykUMN7FDDVpAlLp18IWkRe9Rw2WjyTfZ320u+KdEin5L/tD0poHFuUzmU34U+W1vNSLZOZ21ZGChFpx Yx8w4NVm XjqWryHAuVVv/qdgsFetDT7lhFBa0C6P3rs3rEn5Q1H3XoPvPODeEte3dFEHOrdwCPi8P5I+y5dMxaeWmlrpnPBFNH66ipcIozJWUb/1QRmEvdL41ePaiktnx1qQhYUGuMv3ppf1bf/2EEDQJuOoFxHCOnG1j828Gcdmk1i259g+/O0qgYeQKNZY8SqvDDeanz2dA4A44eMfsWe+McXNlaSzogV4onacXbhA/PiPFjfYK8Bh2y6Vok8/L+iDt9bFD+nft9K6/oKClHqAkJqXo3qtAN8XQxdVa7ozy Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: To enabe batched unmapping of anonymous folios, we need to handle the sharing of exclusive pages. Hence, a batched version of folio_try_share_anon_rmap_pte is required. Currently, the sole purpose of nr_pages in __folio_try_share_anon_rmap is to do some rmap sanity checks. Add helpers to set and clear the PageAnonExclusive bit on a batch of nr_pages. Note that __folio_try_share_anon_rmap can receive nr_pages == HPAGE_PMD_NR from the PMD path, but currently we only clear the bit on the head page. Retain this behaviour by setting nr_pages = 1 in case the caller is folio_try_share_anon_rmap_pmd. While at it, convert nr_pages to unsigned long to future-proof from overflow in case P4D-huge mappings etc get supported down the road. Signed-off-by: Dev Jain --- include/linux/mm.h | 11 +++++++++++ include/linux/rmap.h | 27 ++++++++++++++++++++------- 2 files changed, 31 insertions(+), 7 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 633bbf9a184a6..2d20954da652a 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -243,6 +243,17 @@ static inline unsigned long folio_page_idx(const struct folio *folio, return page - &folio->page; } +static __always_inline void folio_clear_pages_anon_exclusive(struct page *page, + unsigned long nr_pages) +{ + for (;;) { + ClearPageAnonExclusive(page); + if (--nr_pages == 0) + break; + ++page; + } +} + static inline struct folio *lru_to_folio(struct list_head *head) { return list_entry((head)->prev, struct folio, lru); diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 8dc0871e5f001..f3b3ee3955afc 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -706,15 +706,19 @@ static inline int folio_try_dup_anon_rmap_pmd(struct folio *folio, } static __always_inline int __folio_try_share_anon_rmap(struct folio *folio, - struct page *page, int nr_pages, enum pgtable_level level) + struct page *page, unsigned long nr_pages, enum pgtable_level level) { VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); VM_WARN_ON_FOLIO(!PageAnonExclusive(page), folio); __folio_rmap_sanity_checks(folio, page, nr_pages, level); + /* We only clear anon-exclusive from head page of PMD folio */ + if (level == PGTABLE_LEVEL_PMD) + nr_pages = 1; + /* device private folios cannot get pinned via GUP. */ if (unlikely(folio_is_device_private(folio))) { - ClearPageAnonExclusive(page); + folio_clear_pages_anon_exclusive(page, nr_pages); return 0; } @@ -766,7 +770,7 @@ static __always_inline int __folio_try_share_anon_rmap(struct folio *folio, if (unlikely(folio_maybe_dma_pinned(folio))) return -EBUSY; - ClearPageAnonExclusive(page); + folio_clear_pages_anon_exclusive(page, nr_pages); /* * This is conceptually a smp_wmb() paired with the smp_rmb() in @@ -778,11 +782,12 @@ static __always_inline int __folio_try_share_anon_rmap(struct folio *folio, } /** - * folio_try_share_anon_rmap_pte - try marking an exclusive anonymous page - * mapped by a PTE possibly shared to prepare + * folio_try_share_anon_rmap_ptes - try marking exclusive anonymous pages + * mapped by PTEs possibly shared to prepare * for KSM or temporary unmapping * @folio: The folio to share a mapping of - * @page: The mapped exclusive page + * @page: The first mapped exclusive page of the batch in the folio + * @nr_pages: The number of pages to share in the folio (batch size) * * The caller needs to hold the page table lock and has to have the page table * entries cleared/invalidated. @@ -797,11 +802,19 @@ static __always_inline int __folio_try_share_anon_rmap(struct folio *folio, * * Returns 0 if marking the mapped page possibly shared succeeded. Returns * -EBUSY otherwise. + * + * The caller needs to hold the page table lock. */ +static inline int folio_try_share_anon_rmap_ptes(struct folio *folio, + struct page *page, unsigned long nr_pages) +{ + return __folio_try_share_anon_rmap(folio, page, nr_pages, PGTABLE_LEVEL_PTE); +} + static inline int folio_try_share_anon_rmap_pte(struct folio *folio, struct page *page) { - return __folio_try_share_anon_rmap(folio, page, 1, PGTABLE_LEVEL_PTE); + return folio_try_share_anon_rmap_ptes(folio, page, 1); } /** -- 2.34.1