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Subject[34-longterm 003/196] shmem: let shared anonymous be nonlinear again
From: Hugh Dickins <>

This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.

commit bee4c36a5cf5c9f63ce1d7372aa62045fbd16d47 upstream.

Up to 2.6.22, you could use remap_file_pages(2) on a tmpfs file or a
shared mapping of /dev/zero or a shared anonymous mapping. In 2.6.23 we
disabled it by default, but set VM_CAN_NONLINEAR to enable it on safe
mappings. We made sure to set it in shmem_mmap() for tmpfs files, but
missed it in shmem_zero_setup() for the others. Fix that at last.

Reported-by: Kenny Simpson <>
Signed-off-by: Hugh Dickins <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>
Signed-off-by: Paul Gortmaker <>
mm/shmem.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/shmem.c b/mm/shmem.c
index eef4ebe..0203cda 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2701,5 +2701,6 @@ int shmem_zero_setup(struct vm_area_struct *vma)
vma->vm_file = file;
vma->vm_ops = &shmem_vm_ops;
+ vma->vm_flags |= VM_CAN_NONLINEAR;
return 0;

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