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authorLee Schermerhorn <lee.schermerhorn@hp.com>2008-04-28 02:13:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 08:58:24 -0700
commitae4d8c16aa22775f5731677abb8a82f03cec877e (patch)
tree2d34c6fd334b51cc5f3265cd4ec26db758639b5c
parentf4e53d910b7dde2685b177f1e7c3e3e0b4a42f7b (diff)
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mempolicy: fixup Fallback for Default Shmem Policy
get_vma_policy() is not handling fallback to task policy correctly when the get_policy() vm_op returns NULL. The NULL overwrites the 'pol' variable that was holding the fallback task mempolicy. So, it was falling back directly to system default policy. Fix get_vma_policy() to use only non-NULL policy returned from the vma get_policy op. shm_get_policy() was falling back to current task's mempolicy if the "backing file system" [tmpfs vs hugetlbfs] does not support the get_policy vm_op and the vma policy is null. This is incorrect for show_numa_maps() which is likely querying the numa_maps of some task other than current. Remove this fallback. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--ipc/shm.c3
-rw-r--r--mm/mempolicy.c7
2 files changed, 6 insertions, 4 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index cc63fae02f0..8d1b2c468cc 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -274,8 +274,7 @@ static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
else if (vma->vm_policy) {
pol = vma->vm_policy;
mpol_get(pol); /* get_vma_policy() expects this */
- } else
- pol = current->mempolicy;
+ }
return pol;
}
#endif
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c6c61ea6bb8..8924aaf4665 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1262,7 +1262,7 @@ asmlinkage long compat_sys_mbind(compat_ulong_t start, compat_ulong_t len,
* @task != current]. It is the caller's responsibility to
* free the reference in these cases.
*/
-static struct mempolicy * get_vma_policy(struct task_struct *task,
+static struct mempolicy *get_vma_policy(struct task_struct *task,
struct vm_area_struct *vma, unsigned long addr)
{
struct mempolicy *pol = task->mempolicy;
@@ -1270,7 +1270,10 @@ static struct mempolicy * get_vma_policy(struct task_struct *task,
if (vma) {
if (vma->vm_ops && vma->vm_ops->get_policy) {
- pol = vma->vm_ops->get_policy(vma, addr);
+ struct mempolicy *vpol = vma->vm_ops->get_policy(vma,
+ addr);
+ if (vpol)
+ pol = vpol;
shared_pol = 1; /* if pol non-NULL, add ref below */
} else if (vma->vm_policy &&
vma->vm_policy->policy != MPOL_DEFAULT)