Messages in this thread | | | Date | Mon, 11 Jun 2007 21:30:20 -0700 | From | Andrew Morton <> | Subject | Re: [shm][hugetlb] Fix get_policy for stacked shared memory files |
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On Mon, 11 Jun 2007 16:34:54 -0500 Adam Litke <agl@us.ibm.com> wrote:
> Here's another breakage as a result of shared memory stacked files :( > > The NUMA policy for a VMA is determined by checking the following (in the order > given): > > 1) vma->vm_ops->get_policy() (if defined) > 2) vma->vm_policy (if defined) > 3) task->mempolicy (if defined) > 4) Fall back to default_policy > > By switching to stacked files for shared memory, get_policy() is now always set > to shm_get_policy which is a wrapper function. This causes us to stop at step > 1, which yields NULL for hugetlb instead of task->mempolicy which was the > previous (and correct) result. > > This patch modifies the shm_get_policy() wrapper to maintain steps 1-3 for the > wrapped vm_ops. Andi and Christoph, does this look right to you? >
Can we just double-check the refcounting please?
> index 4fefbad..8d2672d 100644 > --- a/ipc/shm.c > +++ b/ipc/shm.c > @@ -254,8 +254,10 @@ struct mempolicy *shm_get_policy(struct vm_area_struct *vma, unsigned long addr) > > if (sfd->vm_ops->get_policy) > pol = sfd->vm_ops->get_policy(vma, addr);
afacit this takes a ref on the underlying policy
> - else > + else if (vma->vm_policy) > pol = vma->vm_policy; > + else > + pol = current->mempolicy;
but these two do not.
> return pol; > } > #endif
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