From ae4d8c16aa22775f5731677abb8a82f03cec877e Mon Sep 17 00:00:00 2001 From: Lee Schermerhorn Date: Mon, 28 Apr 2008 02:13:11 -0700 Subject: [PATCH] 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 Cc: Christoph Lameter Cc: David Rientjes Cc: Mel Gorman Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/shm.c | 3 +-- mm/mempolicy.c | 7 +++++-- 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) -- 2.20.1