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raw | patch | inline | side by side (parent: f4846e5)
author | Michel Lespinasse <walken@google.com> | |
Thu, 14 Mar 2013 23:50:02 +0000 (16:50 -0700) | ||
committer | Linus Torvalds <torvalds@linux-foundation.org> | |
Fri, 15 Mar 2013 00:00:39 +0000 (17:00 -0700) |
The vm_flags introduced in 6d7825b10dbe ("mm/fremap.c: fix oops on error
path") is supposed to avoid a compiler warning about unitialized
vm_flags without changing the generated code.
However I am concerned that this is going to be very brittle, and fail
with some compiler versions. The failure could be either of:
- compiler could actually load vma->vm_flags before checking for the
!vma condition, thus reintroducing the oops
- compiler could optimize out the !vma check, since the pointer just got
dereferenced shortly before (so the compiler knows it can't be NULL!)
I propose reversing this part of the change and initializing vm_flags to 0
just to avoid the bogus uninitialized use warning.
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
path") is supposed to avoid a compiler warning about unitialized
vm_flags without changing the generated code.
However I am concerned that this is going to be very brittle, and fail
with some compiler versions. The failure could be either of:
- compiler could actually load vma->vm_flags before checking for the
!vma condition, thus reintroducing the oops
- compiler could optimize out the !vma check, since the pointer just got
dereferenced shortly before (so the compiler knows it can't be NULL!)
I propose reversing this part of the change and initializing vm_flags to 0
just to avoid the bogus uninitialized use warning.
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/fremap.c | patch | blob | history |
diff --git a/mm/fremap.c b/mm/fremap.c
index 6a8da7ee85fd58e7d0857a185239ef6af57a61d8..4723ac8d2fc200d5990f830b6f4c8c0fd2a9bbcf 100644 (file)
--- a/mm/fremap.c
+++ b/mm/fremap.c
struct vm_area_struct *vma;
int err = -EINVAL;
int has_write_lock = 0;
- vm_flags_t vm_flags;
+ vm_flags_t vm_flags = 0;
if (prot)
return err;
* and that the remapped range is valid and fully within
* the single existing vma.
*/
- vm_flags = vma->vm_flags;
- if (!vma || !(vm_flags & VM_SHARED))
+ if (!vma || !(vma->vm_flags & VM_SHARED))
goto out;
if (!vma->vm_ops || !vma->vm_ops->remap_pages)