The patch titled
Subject: userfaultfd: fix remap event with MREMAP_DONTUNMAP.
has been added to the -mm tree. Its filename is
userfaultfd-fix-remap-event-with-mremap_dontunmap.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-fix-remap-event-with-mremap_dontunmap.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-fix-remap-event-with-mremap_dontunmap.patch
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------------------------------------------------------
From: Brian Geffon <bgeffon@xxxxxxxxxx>
Subject: userfaultfd: fix remap event with MREMAP_DONTUNMAP.
A user is not required to set a new address when using MREMAP_DONTUNMAP as
it can be used without MREMAP_FIXED. When doing so the remap event will
use new_addr which may not have been set and we didn't propagate it back
other then in the return value of remap_to.
Because ret is always the new address it's probably more correct to use it
rather than new_addr on the remap_event_complete call, and it resolves
this bug.
Link: http://lkml.kernel.org/r/20200506172158.218366-1-bgeffon@xxxxxxxxxx
Fixes: e346b3813067d4b ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Signed-off-by: Brian Geffon <bgeffon@xxxxxxxxxx>
Cc: Lokesh Gidra <lokeshgidra@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: "Michael S . Tsirkin" <mst@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Sonny Rao <sonnyrao@xxxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mremap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mremap.c~userfaultfd-fix-remap-event-with-mremap_dontunmap
+++ a/mm/mremap.c
@@ -794,7 +794,7 @@ out:
if (locked && new_len > old_len)
mm_populate(new_addr + old_len, new_len - old_len);
userfaultfd_unmap_complete(mm, &uf_unmap_early);
- mremap_userfaultfd_complete(&uf, addr, new_addr, old_len);
+ mremap_userfaultfd_complete(&uf, addr, ret, old_len);
userfaultfd_unmap_complete(mm, &uf_unmap);
return ret;
}
_
Patches currently in -mm which might be from bgeffon@xxxxxxxxxx are
userfaultfd-fix-remap-event-with-mremap_dontunmap.patch
