From a7a69d8ba88d8dcee7ef00e91d413a4bd003a814 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 24 Jun 2021 18:39:30 -0700 Subject: mm/thp: another PVMW_SYNC fix in page_vma_mapped_walk() Aha! Shouldn't that quick scan over pte_none()s make sure that it holds ptlock in the PVMW_SYNC case? That too might have been responsible for BUGs or WARNs in split_huge_page_to_list() or its unmap_page(), though I've never seen any. Link: https://lkml.kernel.org/r/1bdf384c-8137-a149-2a1e-475a4791c3c@google.com Link: https://lore.kernel.org/linux-mm/20210412180659.B9E3.409509F4@e16-tech.com/ Fixes: ace71a19cec5 ("mm: introduce page_vma_mapped_walk()") Signed-off-by: Hugh Dickins Acked-by: Kirill A. Shutemov Tested-by: Wang Yugui Cc: Alistair Popple Cc: Matthew Wilcox Cc: Peter Xu Cc: Ralph Campbell Cc: Will Deacon Cc: Yang Shi Cc: Zi Yan Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_vma_mapped.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'mm/page_vma_mapped.c') diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index a4e962b510c7..a4435311754b 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -276,6 +276,10 @@ next_pte: goto restart; } pvmw->pte++; + if ((pvmw->flags & PVMW_SYNC) && !pvmw->ptl) { + pvmw->ptl = pte_lockptr(mm, pvmw->pmd); + spin_lock(pvmw->ptl); + } } while (pte_none(*pvmw->pte)); if (!pvmw->ptl) { -- cgit