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This means instead of making the entire original folio unusable memory failure code would only make its after-split folio, which has order of min_order_for_split() and contains HWPoison page, unusable. For soft offline case, since the original folio is still accessible, no split is performed if the folio cannot be split to order-0 to prevent potential performance loss. In addition, add split_huge_page_to_order() to improve code readability and fix kernel-doc comment format for folio_split() and other related functions. It is based on mm-new without V4 of this patchset. Background === This patchset is a follow-up of "[PATCH v3] mm/huge_memory: do not change split_huge_page*() target order silently."[1] and [PATCH v4] mm/huge_memory: preserve PG_has_hwpoisoned if a folio is split to >0 order[2], since both are separated out as hotfixes. It improves how memory failure code handles large block size(LBS) folios with min_order_for_split() > 0. By splitting a large folio containing HW poisoned pages to min_order_for_split(), the after-split folios without HW poisoned pages could be freed for reuse. To achieve this, folio split code needs to set has_hwpoisoned on after-split folios containing HW poisoned pages and it is done in the hotfix in [2]. This patchset includes: 1. A patch adds split_huge_page_to_order(), 2. Patch 2 and Patch 3 of "[PATCH v2 0/3] Do not change split folio target order"[3], Changelog === >From V4[5]: 1. updated cover letter. 2. updated __split_unmapped_folio() comment and removed stale text. >From V3[4]: 1. Patch, mm/huge_memory: preserve PG_has_hwpoisoned if a folio is split to >0 order, is sent separately as a hotfix[2]. 2. made newly added new_order const in memory_failure() and soft_offline_in_use_page(). 3. explained in a comment why in memory_failure() after-split >0 order folios are still treated as if the split failed. >From V2[3]: 1. Patch 1 is sent separately as a hotfix[1]. 2. set has_hwpoisoned on after-split folios if any contains HW poisoned pages. 3. added split_huge_page_to_order(). 4. added a missing newline after variable decalaration. 5. added /* release= */ to try_to_split_thp_page(). 6. restructured try_to_split_thp_page() in memory_failure(). 7. fixed a typo. 8. reworded the comment in soft_offline_in_use_page() for better understanding. Link: https://lore.kernel.org/all/20251017013630.139907-1-ziy@nvidia.com/ [1] Link: https://lore.kernel.org/all/20251023030521.473097-1-ziy@nvidia.com/ [2] Link: https://lore.kernel.org/all/20251016033452.125479-1-ziy@nvidia.com/ [3] Link: https://lore.kernel.org/all/20251022033531.389351-1-ziy@nvidia.com/ [4] Link: https://lore.kernel.org/all/20251030014020.475659-1-ziy@nvidia.com/ [5] Zi Yan (3): mm/huge_memory: add split_huge_page_to_order() mm/memory-failure: improve large block size folio handling. mm/huge_memory: fix kernel-doc comments for folio_split() and related. include/linux/huge_mm.h | 22 ++++++++++++++------ mm/huge_memory.c | 45 ++++++++++++++++++++++------------------- mm/memory-failure.c | 31 ++++++++++++++++++++++++---- 3 files changed, 67 insertions(+), 31 deletions(-) -- 2.51.0