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From c0205eaf3af9f5db14d4b5ee4abacf4a583c3c50 Mon Sep 17 00:00:00 2001
From: Lokesh Gidra <lokeshgidra@google.com>
Date: Thu, 4 Apr 2024 10:17:26 -0700
Subject: userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE
From: Lokesh Gidra <lokeshgidra@google.com>
commit c0205eaf3af9f5db14d4b5ee4abacf4a583c3c50 upstream.
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 <lokeshgidra@google.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Nicolas Geoffray <ngeoffray@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/huge_memory.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2244,9 +2244,6 @@ int move_pages_huge_pmd(struct mm_struct
goto unlock_ptls;
}
- folio_move_anon_rmap(src_folio, 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)) {
@@ -2255,6 +2252,9 @@ int move_pages_huge_pmd(struct mm_struct
goto unlock_ptls;
}
+ folio_move_anon_rmap(src_folio, 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), dst_vma);
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