File-backed memory can be backed by THPs either through collapse, when CONFIG_READ_ONLY_THP_FOR_FS is enabled, or through fault, when the filesystem supports large folio mappings. Currently, smaps only knows about the former, so teach it about the latter. Signed-off-by: Zach O'Keefe <zokeefe@xxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> --- mm/huge_memory.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index cd379b2c077b..d8d6e83820f3 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -136,7 +136,16 @@ bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags, */ !!vma->vm_ops->huge_fault : /* Only regular file is valid in collapse path */ - file_thp_enabled(vma); + file_thp_enabled(vma) || + /* + * THPeligible bit of smaps should surface the + * possibility of THP through fault if the filesystem + * supports it. We don't check this in fault path, + * because we want to fallback to the actual ->fault() + * handler to make the decision. + */ + (smaps && vma->vm_file && + mapping_large_folio_support(vma->vm_file->f_mapping)); if (vma_is_temporary_stack(vma)) return false; -- 2.42.0.rc1.204.g551eb34607-goog
