Messages in this thread | | | Date | Thu, 03 Jan 2013 01:20:06 -0500 | From | Rik van Riel <> | Subject | Re: [PATCH 9/9] mm: introduce VM_POPULATE flag to better deal with racy userspace programs |
| |
On 12/20/2012 07:49 PM, Michel Lespinasse wrote: > The vm_populate() code populates user mappings without constantly > holding the mmap_sem. This makes it susceptible to racy userspace > programs: the user mappings may change while vm_populate() is running, > and in this case vm_populate() may end up populating the new mapping > instead of the old one. > > In order to reduce the possibility of userspace getting surprised by > this behavior, this change introduces the VM_POPULATE vma flag which > gets set on vmas we want vm_populate() to work on. This way > vm_populate() may still end up populating the new mapping after such a > race, but only if the new mapping is also one that the user has > requested (using MAP_SHARED, MAP_LOCKED or mlock) to be populated. > > Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <ri
-- All rights reversed
| |