PATCH 04/15 Mempolicy: Fixup Fallback for Default Shmem/Shm Policy Against: 2.6.25-rc8-mm1 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@xxxxxx> ipc/shm.c | 3 +-- mm/mempolicy.c | 7 +++++-- 2 files changed, 6 insertions(+), 4 deletions(-) Index: linux-2.6.25-rc8-mm1/mm/mempolicy.c =================================================================== --- linux-2.6.25-rc8-mm1.orig/mm/mempolicy.c 2008-04-02 17:32:35.000000000 -0400 +++ linux-2.6.25-rc8-mm1/mm/mempolicy.c 2008-04-03 15:44:48.000000000 -0400 @@ -1262,7 +1262,7 @@ asmlinkage long compat_sys_mbind(compat_ * @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 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) Index: linux-2.6.25-rc8-mm1/ipc/shm.c =================================================================== --- linux-2.6.25-rc8-mm1.orig/ipc/shm.c 2008-04-02 17:09:54.000000000 -0400 +++ linux-2.6.25-rc8-mm1/ipc/shm.c 2008-04-03 15:27:46.000000000 -0400 @@ -255,8 +255,7 @@ static struct mempolicy *shm_get_policy( else if (vma->vm_policy) { pol = vma->vm_policy; mpol_get(pol); /* get_vma_policy() expects this */ - } else - pol = current->mempolicy; + } return pol; } #endif -- To unsubscribe from this list: send the line "unsubscribe linux-numa" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html