FAILED: patch "[PATCH] userfaultfd: change src_folio after ensuring it's unpinned in" failed to apply to 6.8-stable tree

FAILED: patch "[PATCH] userfaultfd: change src_folio after ensuring it's unpinned in" failed to apply to 6.8-stable tree

[gregkh]

The patch below does not apply to the 6.8-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.8.y
git checkout FETCH_HEAD
git cherry-pick -x c0205eaf3af9f5db14d4b5ee4abacf4a583c3c50
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024042334-agenda-nutlike-cb77@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..

Possible dependencies:

c0205eaf3af9 ("userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE")
eb1521dad8f3 ("userfaultfd: handle zeropage moves by UFFDIO_MOVE")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

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: [PATCH] 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 <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>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9859aa4f7553..89f58c7603b2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2259,9 +2259,6 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm
 			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)) {
@@ -2270,6 +2267,9 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm
 			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);

[PATCH 6.8.y] userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE

[Lokesh Gidra]

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>
(cherry picked from commit c0205eaf3af9f5db14d4b5ee4abacf4a583c3c50)
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
---
 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 94c958f7ebb5..6790f93fda45 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2244,9 +2244,6 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm
 		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 *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm
 		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);
-- 
2.44.0.769.g3c40516874-goog

Re: [PATCH 6.8.y] userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE

[Greg KH]

On Tue, Apr 23, 2024 at 10:52:38AM -0700, Lokesh Gidra wrote:
> 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>
> (cherry picked from commit c0205eaf3af9f5db14d4b5ee4abacf4a583c3c50)
> Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>

Now queued up, thanks.

greg k-h