From 4f658d77230e4d34734632f41af8267f93547dbb Mon Sep 17 00:00:00 2001 From: Lokesh Gidra Date: Thu, 4 Apr 2024 10:17:26 -0700 Subject: [PATCH] BACKPORT: userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE Commit d7a08838ab74 ("mm: userfaultfd: fix unexpected change to src_folio when UFFDIO_MOVE fails") moved the src_folio->{mapping, index} changing to after clearing the page-table and ensuring that it's not pinned. This avoids failure of swapout+migration and possibly memory corruption. However, the commit missed fixing it in the huge-page case. Link: https://lkml.kernel.org/r/20240404171726.2302435-1-lokeshgidra@google.com Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") Signed-off-by: Lokesh Gidra Acked-by: David Hildenbrand Cc: Andrea Arcangeli Cc: Kalesh Singh Cc: Lokesh Gidra Cc: Nicolas Geoffray Cc: Peter Xu Cc: Qi Zheng Cc: Matthew Wilcox Cc: Signed-off-by: Andrew Morton (cherry picked from commit c0205eaf3af9f5db14d4b5ee4abacf4a583c3c50) Conflicts: mm/huge_memory.c 1. Replace folio_move_anon_rmap() with page_move_anon_rmap(). Bug: 274911254 Change-Id: I15a07ea22de7ae38ed20320a73c995c7c48ef42b Signed-off-by: Lokesh Gidra --- mm/huge_memory.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 243b1390e9bd..1bc744166e9b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2013,9 +2013,6 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm goto unlock_ptls; } - page_move_anon_rmap(&src_folio->page, dst_vma); - WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr)); - src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); /* Folio got pinned from under us. Put it back and fail the move. */ if (folio_maybe_dma_pinned(src_folio)) { @@ -2024,6 +2021,9 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm goto unlock_ptls; } + page_move_anon_rmap(&src_folio->page, dst_vma); + WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr)); + _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot); /* Follow mremap() behavior and treat the entry dirty after the move */ _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd));