kernel/linux.git/mm/page_isolation.c, branch v7.1

mm: page_isolation: introduce page_is_unmovable()

2026-01-31T22:22:42+00:00

Patch series "mm: accelerate gigantic folio allocation". Optimize pfn_range_valid_contig() and replace_free_hugepage_folios() in alloc_contig_frozen_pages() to speed up gigantic folio allocation. The allocation time for 120*1G folios drops from 3.605s to 0.431s. This patch (of 5): Factor out the check if a page is unmovable into a new helper, and will be reused in the following patch. No functional change intended, the minor changes are as follows, 1) Avoid unnecessary calls by checking CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION 2) Directly call PageCompound since PageTransCompound may be dropped 3) Using folio_test_hugetlb() Link: https://lkml.kernel.org/r/20260112150954.1802953-1-wangkefeng.wang@huawei.com Link: https://lkml.kernel.org/r/20260112150954.1802953-2-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Reviewed-by: Zi Yan Reviewed-by: Oscar Salvador Cc: Brendan Jackman Cc: David Hildenbrand Cc: Jane Chu Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Cc: Muchun Song Cc: Sidhartha Kumar Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: fix minor spelling mistakes in comments

2026-01-21T03:24:48+00:00

Correct several typos in comments across files in mm/ [akpm@linux-foundation.org: also fix comment grammar, per SeongJae] Link: https://lkml.kernel.org/r/20251218150906.25042-1-klourencodev@gmail.com Signed-off-by: Kevin Lourenco Reviewed-by: SeongJae Park Acked-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Signed-off-by: Andrew Morton

mm/page_isolation: drop __folio_test_movable() check for large folios

2025-07-13T23:38:29+00:00

Currently, we only support migration of individual movable_ops pages, so we can not run into that. Link: https://lkml.kernel.org/r/20250704102524.326966-18-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Zi Yan Reviewed-by: Lorenzo Stoakes Reviewed-by: Harry Yoo Cc: Alistair Popple Cc: Al Viro Cc: Arnd Bergmann Cc: Brendan Jackman Cc: Byungchul Park Cc: Chengming Zhou Cc: Christian Brauner Cc: Christophe Leroy Cc: Eugenio Pé rez Cc: Greg Kroah-Hartman Cc: Gregory Price Cc: "Huang, Ying" Cc: Jan Kara Cc: Jason Gunthorpe Cc: Jason Wang Cc: Jerrin Shaji George Cc: Johannes Weiner Cc: John Hubbard Cc: Jonathan Corbet Cc: Joshua Hahn Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Mathew Brost Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Michael Ellerman Cc: "Michael S. Tsirkin" Cc: Michal Hocko Cc: Mike Rapoport Cc: Minchan Kim Cc: Naoya Horiguchi Cc: Nicholas Piggin Cc: Oscar Salvador Cc: Peter Xu Cc: Qi Zheng Cc: Rakie Kim Cc: Rik van Riel Cc: Sergey Senozhatsky Cc: Shakeel Butt Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: xu xin Signed-off-by: Andrew Morton

mm: rename __PageMovable() to page_has_movable_ops()

2025-07-13T23:38:29+00:00

Let's make it clearer that we are talking about movable_ops pages. While at it, convert a VM_BUG_ON to a VM_WARN_ON_ONCE_PAGE. Link: https://lkml.kernel.org/r/20250704102524.326966-17-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Zi Yan Reviewed-by: Lorenzo Stoakes Reviewed-by: Harry Yoo Cc: Alistair Popple Cc: Al Viro Cc: Arnd Bergmann Cc: Brendan Jackman Cc: Byungchul Park Cc: Chengming Zhou Cc: Christian Brauner Cc: Christophe Leroy Cc: Eugenio Pé rez Cc: Greg Kroah-Hartman Cc: Gregory Price Cc: "Huang, Ying" Cc: Jan Kara Cc: Jason Gunthorpe Cc: Jason Wang Cc: Jerrin Shaji George Cc: Johannes Weiner Cc: John Hubbard Cc: Jonathan Corbet Cc: Joshua Hahn Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Mathew Brost Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Michael Ellerman Cc: "Michael S. Tsirkin" Cc: Michal Hocko Cc: Mike Rapoport Cc: Minchan Kim Cc: Naoya Horiguchi Cc: Nicholas Piggin Cc: Oscar Salvador Cc: Peter Xu Cc: Qi Zheng Cc: Rakie Kim Cc: Rik van Riel Cc: Sergey Senozhatsky Cc: Shakeel Butt Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: xu xin Signed-off-by: Andrew Morton

mm/page_isolation: remove migratetype parameter from more functions

2025-07-13T23:38:18+00:00

migratetype is no longer overwritten during pageblock isolation, start_isolate_page_range(), has_unmovable_pages(), and set_migratetype_isolate() no longer need which migratetype to restore during isolation failure. For has_unmoable_pages(), it needs to know if the isolation is for CMA allocation, so adding PB_ISOLATE_MODE_CMA_ALLOC provide the information. At the same time change isolation flags to enum pb_isolate_mode (PB_ISOLATE_MODE_MEM_OFFLINE, PB_ISOLATE_MODE_CMA_ALLOC, PB_ISOLATE_MODE_OTHER). Remove REPORT_FAILURE and check PB_ISOLATE_MODE_MEM_OFFLINE, since only PB_ISOLATE_MODE_MEM_OFFLINE reports isolation failures. alloc_contig_range() no longer needs migratetype. Replace it with a newly defined acr_flags_t to tell if an allocation is for CMA. So does __alloc_contig_migrate_range(). Add ACR_FLAGS_NONE (set to 0) to indicate ordinary allocations. Link: https://lkml.kernel.org/r/20250617021115.2331563-7-ziy@nvidia.com Signed-off-by: Zi Yan Reviewed-by: Vlastimil Babka Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Brendan Jackman Cc: Johannes Weiner Cc: Kirill A. Shuemov Cc: Mel Gorman Cc: Michal Hocko Cc: Oscar Salvador Cc: Richard Chang Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton

mm/page_isolation: remove migratetype from undo_isolate_page_range()

2025-07-13T23:38:18+00:00

Since migratetype is no longer overwritten during pageblock isolation, undoing pageblock isolation no longer needs which migratetype to restore. Link: https://lkml.kernel.org/r/20250617021115.2331563-6-ziy@nvidia.com Signed-off-by: Zi Yan Acked-by: David Hildenbrand Reviewed-by: Vlastimil Babka Cc: Baolin Wang Cc: Brendan Jackman Cc: Johannes Weiner Cc: Kirill A. Shuemov Cc: Mel Gorman Cc: Michal Hocko Cc: Oscar Salvador Cc: Richard Chang Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton

mm/page_isolation: remove migratetype from move_freepages_block_isolate()

2025-07-13T23:38:18+00:00

Since migratetype is no longer overwritten during pageblock isolation, moving a pageblock out of MIGRATE_ISOLATE no longer needs a new migratetype. Add pageblock_isolate_and_move_free_pages() and pageblock_unisolate_and_move_free_pages() to be explicit about the page isolation operations. Both share the common code in __move_freepages_block_isolate(), which is renamed from move_freepages_block_isolate(). Add toggle_pageblock_isolate() to flip pageblock isolation bit in __move_freepages_block_isolate(). Make set_pageblock_migratetype() only accept non MIGRATE_ISOLATE types, so that one should use set_pageblock_isolate() to isolate pageblocks. As a result, move pageblock migratetype code out of __move_freepages_block(). Link: https://lkml.kernel.org/r/20250617021115.2331563-5-ziy@nvidia.com Signed-off-by: Zi Yan Reviewed-by: Vlastimil Babka Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Brendan Jackman Cc: Johannes Weiner Cc: Kirill A. Shuemov Cc: Mel Gorman Cc: Michal Hocko Cc: Oscar Salvador Cc: Richard Chang Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton

mm: page_isolation: avoid calling folio_hstate() without hugetlb_lock

2025-04-01T22:14:43+00:00

I found a NULL pointer dereference as followed: BUG: kernel NULL pointer dereference, address: 0000000000000028 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP PTI CPU: 5 UID: 0 PID: 5964 Comm: sh Kdump: loaded Not tainted 6.13.0-dirty #20 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1. RIP: 0010:has_unmovable_pages+0x184/0x360 ... Call Trace: set_migratetype_isolate+0xd1/0x180 start_isolate_page_range+0xd2/0x170 alloc_contig_range_noprof+0x101/0x660 alloc_contig_pages_noprof+0x238/0x290 alloc_gigantic_folio.isra.0+0xb6/0x1f0 only_alloc_fresh_hugetlb_folio.isra.0+0xf/0x60 alloc_pool_huge_folio+0x80/0xf0 set_max_huge_pages+0x211/0x490 __nr_hugepages_store_common+0x5f/0xe0 nr_hugepages_store+0x77/0x80 kernfs_fop_write_iter+0x118/0x200 vfs_write+0x23c/0x3f0 ksys_write+0x62/0xe0 do_syscall_64+0x5b/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e As has_unmovable_pages() call folio_hstate() without hugetlb_lock, there is a race to free the HugeTLB page between PageHuge() and folio_hstate(). There is no need to add hugetlb_lock here as the HugeTLB page can be freed in lot of places. So it's enough to unfold folio_hstate() and add a check to avoid NULL pointer dereference for hugepage_migration_supported(). Link: https://lkml.kernel.org/r/20250122061151.578768-1-liushixin2@huawei.com Fixes: 464c7ffbcb16 ("mm/hugetlb: filter out hugetlb pages if HUGEPAGE migration is not supported.") Signed-off-by: Liu Shixin Acked-by: David Hildenbrand Acked-by: Zi Yan Reviewed-by: Oscar Salvador Cc: Johannes Weiner Cc: Kefeng Wang Cc: Kirill A. Shuemov Cc: Muchun Song Cc: Nanyong Sun Signed-off-by: Andrew Morton

mm/hugetlb: wait for hugetlb folios to be freed

2025-03-06T05:36:14+00:00

Since the introduction of commit c77c0a8ac4c52 ("mm/hugetlb: defer freeing of huge pages if in non-task context"), which supports deferring the freeing of hugetlb pages, the allocation of contiguous memory through cma_alloc() may fail probabilistically. In the CMA allocation process, if it is found that the CMA area is occupied by in-use hugetlb folios, these in-use hugetlb folios need to be migrated to another location. When there are no available hugetlb folios in the free hugetlb pool during the migration of in-use hugetlb folios, new folios are allocated from the buddy system. A temporary state is set on the newly allocated folio. Upon completion of the hugetlb folio migration, the temporary state is transferred from the new folios to the old folios. Normally, when the old folios with the temporary state are freed, it is directly released back to the buddy system. However, due to the deferred freeing of hugetlb pages, the PageBuddy() check fails, ultimately leading to the failure of cma_alloc(). Here is a simplified call trace illustrating the process: cma_alloc() ->__alloc_contig_migrate_range() // Migrate in-use hugetlb folios ->unmap_and_move_huge_page() ->folio_putback_hugetlb() // Free old folios ->test_pages_isolated() ->__test_page_isolated_in_pageblock() ->PageBuddy(page) // Check if the page is in buddy To resolve this issue, we have implemented a function named wait_for_freed_hugetlb_folios(). This function ensures that the hugetlb folios are properly released back to the buddy system after their migration is completed. By invoking wait_for_freed_hugetlb_folios() before calling PageBuddy(), we ensure that PageBuddy() will succeed. Link: https://lkml.kernel.org/r/1739936804-18199-1-git-send-email-yangge1116@126.com Fixes: c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") Signed-off-by: Ge Yang Reviewed-by: Muchun Song Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Barry Song <21cnbao@gmail.com> Cc: Oscar Salvador Cc: Signed-off-by: Andrew Morton

mm/page_isolation: don't pass gfp flags to start_isolate_page_range()

2025-01-14T06:40:44+00:00

The parameter is unused, so let's stop passing it. Link: https://lkml.kernel.org/r/20241203094732.200195-3-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Zi Yan Reviewed-by: Vlastimil Babka Reviewed-by: Oscar Salvador Reviewed-by: Vishal Moola (Oracle) Cc: Christophe Leroy Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Naveen N Rao Cc: Nicholas Piggin Signed-off-by: Andrew Morton