collapse_file() requires FSes supporting large folio with at least PMD_ORDER, so replace the READ_ONLY_THP_FOR_FS check with that. MADV_COLLAPSE ignores shmem huge config, so exclude the check for shmem.
While at it, replace VM_BUG_ON with VM_WARN_ON_ONCE. Add a helper function mapping_pmd_folio_support() for FSes supporting large folio with at least PMD_ORDER. Signed-off-by: Zi Yan <[email protected]> Reviewed-by: Lance Yang <[email protected]> Reviewed-by: Baolin Wang <[email protected]> --- include/linux/pagemap.h | 26 ++++++++++++++++++++++++++ mm/khugepaged.c | 10 ++++++++-- 2 files changed, 34 insertions(+), 2 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 1f50991b43e3b..1fed3414fe9b8 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -513,6 +513,32 @@ static inline bool mapping_large_folio_support(const struct address_space *mappi return mapping_max_folio_order(mapping) > 0; } +/** + * mapping_pmd_folio_support() - Check if a mapping support PMD-sized folio + * @mapping: The address_space + * + * Some file supports large folio but does not support as large as PMD order. + * If a PMD-sized pagecache folio is attempted to be created on a filesystem, + * this check needs to be performed first. + * + * Return: true - PMD-sized folio is supported, false - PMD-sized folio is not + * supported. + */ +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline bool mapping_pmd_folio_support(const struct address_space *mapping) +{ + /* AS_FOLIO_ORDER is only reasonable for pagecache folios */ + VM_WARN_ON_ONCE((unsigned long)mapping & FOLIO_MAPPING_ANON); + + return mapping_max_folio_order(mapping) >= PMD_ORDER; +} +#else +static inline bool mapping_pmd_folio_support(const struct address_space *mapping) +{ + return false; +} +#endif + /* Return the maximum folio size for this pagecache mapping, in bytes. */ static inline size_t mapping_max_folio_size(const struct address_space *mapping) { diff --git a/mm/khugepaged.c b/mm/khugepaged.c index e112525c4aa9c..6808f2b48d864 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2235,8 +2235,14 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, int nr_none = 0; bool is_shmem = shmem_file(file); - VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); - VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); + /* + * MADV_COLLAPSE ignores shmem huge config, so do not check shmem + * + * TODO: once shmem always calls mapping_set_large_folios() on its + * mapping, the shmem check can be removed. + */ + VM_WARN_ON_ONCE(!is_shmem && !mapping_pmd_folio_support(mapping)); + VM_WARN_ON_ONCE(start & (HPAGE_PMD_NR - 1)); result = alloc_charge_folio(&new_folio, mm, cc, HPAGE_PMD_ORDER); if (result != SCAN_SUCCEED) -- 2.53.0
