Originally, walk_hugetlb_range() didn't require a caller take any lock. But commit d33b9f45bd (mm: hugetlb: fix hugepage memory leak in walk_page_range) changed its rule. Because it added find_vma() call in walk_hugetlb_range(). Any locking-rule change commit should write a doc too. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> --- include/linux/mm.h | 1 + mm/pagewalk.c | 3 +++ 2 files changed, 4 insertions(+), 0 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index dd87a78..7337b66 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -921,6 +921,7 @@ unsigned long unmap_vmas(struct mmu_gather **tlb, * @pte_entry: if set, called for each non-empty PTE (4th-level) entry * @pte_hole: if set, called for each hole at all levels * @hugetlb_entry: if set, called for each hugetlb entry + * *Caution*: The caller must hold mmap_sem() if it's used. * * (see walk_page_range for more details) */ diff --git a/mm/pagewalk.c b/mm/pagewalk.c index ee4ff87..f792940 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -181,6 +181,9 @@ static int walk_hugetlb_range(struct vm_area_struct *vma, * * If any callback returns a non-zero value, the walk is aborted and * the return value is propagated back to the caller. Otherwise 0 is returned. + * + * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry + * is !NULL. */ int walk_page_range(unsigned long addr, unsigned long end, struct mm_walk *walk) -- 1.7.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>