2db5798382
Patch series "mm: Improve mlock tracking for large folios", v3. The patchset includes several fixes and improvements related to mlock tracking of large folios. The main objective is to reduce the undercount of Mlocked memory in /proc/meminfo and improve the accuracy of the statistics. Patches 1-2: These patches address a minor race condition in folio_referenced_one() related to mlock_vma_folio(). Currently, mlock_vma_folio() is called on large folio without the page table lock, which can result in a race condition with unmap (i.e. MADV_DONTNEED). This can lead to partially mapped folios on the unevictable LRU list. While not a significant issue, I do not believe backporting is necessary. Patch 3: This patch adds mlocking logic similar to folio_referenced_one() to try_to_unmap_one(), allowing for mlocking of large folios where possible. Patch 4-5: These patches modifies finish_fault() and faultaround to map in the entire folio when possible, enabling efficient mlocking upon addition to the rmap. Patch 6: This patch makes rmap mlock large folios if they are fully mapped, addressing the primary source of mlock undercount for large folios. This patch (of 6): Add a PVMW_PGTABLE_CROSSSED flag that page_vma_mapped_walk() will set if the page is mapped across page table boundary. Unlike other PVMW_* flags, this one is result of page_vma_mapped_walk() and not set by the caller. folio_referenced_one() will use it to detect if it safe to mlock the folio. [akpm@linux-foundation.org: s/CROSSSED/CROSSED/] Link: https://lkml.kernel.org/r/20250923110711.690639-1-kirill@shutemov.name Link: https://lkml.kernel.org/r/20250923110711.690639-2-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau <kas@kernel.org> Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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