From 023e1a8dd502405ba378a7fbb1ce62beb0616708 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Wed, 7 Jul 2021 13:11:24 -0700 Subject: [PATCH] mm/rmap: fix new bug: premature return from page_mlock_one() In the unlikely race case that page_mlock_one() finds VM_LOCKED has been cleared by the time it got page table lock, page_vma_mapped_walk_done() must be called before returning, either explicitly, or by a final call to page_vma_mapped_walk() - otherwise the page table remains locked. Fixes: cd62734ca60d ("mm/rmap: split try_to_munlock from try_to_unmap") Signed-off-by: Hugh Dickins Reviewed-by: Alistair Popple Reviewed-by: Shakeel Butt Reported-by: kernel test robot Link: https://lore.kernel.org/lkml/20210711151446.GB4070@xsang-OptiPlex-9020/ Link: https://lore.kernel.org/lkml/f71f8523-cba7-3342-40a7-114abc5d1f51@google.com/ Cc: Andrew Morton Cc: Jason Gunthorpe Cc: Ralph Campbell Cc: Christoph Hellwig Cc: Yang Shi Cc: Kirill A. Shutemov Signed-off-by: Linus Torvalds --- mm/rmap.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 0e83c3be8568..1235368f0628 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1990,14 +1990,13 @@ static bool page_mlock_one(struct page *page, struct vm_area_struct *vma, * this function is never called when PageDoubleMap(). */ mlock_vma_page(page); + /* + * No need to scan further once the page is marked + * as mlocked. + */ page_vma_mapped_walk_done(&pvmw); + return false; } - - /* - * no need to continue scanning other vma's if the page has - * been locked. - */ - return false; } return true; -- GitLab