From: Michel Lespinasse <walken@google.com>
Date: Thu, 14 Mar 2013 23:50:02 +0000 (-0700)
Subject: mm/fremap.c: fix possible oops on error path
X-Git-Tag: v3.9-rc3~12
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a2362d24764a4e9a3187fc46b14e1d2cd0657700;p=pandora-kernel.git

mm/fremap.c: fix possible oops on error path

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>
---

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