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Patch 1, 2: dereferencing NULL folio->mapping in try_folio_split_to_order() for future users, 2. Patch 3: improper handling of negative return value of min_order_for_split() in mm/memory-failure.c No bug is present for the existing code. For 1, try_folio_split_to_order() is used in truncate_inode_partial_folio() and it is fine since folio->mapping is always not NULL there. For 2, mm/memory-failure.c code does not check for -EBUSY return value of min_order_for_split() and directly passes it to a folio split function. The code works by accident but needs to be fixed. folio_split_supported() does not check if folio->mapping is NULL, but can dereference it in some cases. My current fix is adding a kernel-doc to clarify this requirement. An alternative is to add folio->mapping check and return -EBUSY and return -EINVAL for the other checks. But folio_split_supported() will no longer checks for "supported", folio_split_can_split() might be a better name. Then, the existing can_split_folio() might better be renamed to folio_split_refcount_check(). In addition, try_folio_split_to_order(), which calls folio_split_supported(), might want to handle -EBUSY separately to avoid calling split_huge_page_to_order() when the folio is truncated for a known -EBUSY error. Let me know your thoughts. Thanks. Link: https://lore.kernel.org/all/20251120004735.52z7r4xmogw7mbsj@master/ [1] Zi Yan (3): mm/huge_memory: prevent NULL pointer dereference in try_folio_split_to_order() mm/huge_memory: add kernel-doc for folio_split_supported() mm/memory-failure: handle min_order_for_split() error code properly include/linux/huge_mm.h | 7 +++++++ mm/huge_memory.c | 17 +++++++++++++++++ mm/memory-failure.c | 8 ++++++-- 3 files changed, 30 insertions(+), 2 deletions(-) -- 2.51.0