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mempolicy: remove the "task" arg of vma_policy_mof() and simplify it

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1. vma_policy_mof(task) is simply not safe unless task == current,
   it can race with do_exit()->mpol_put(). Remove this arg and update
   its single caller.

2. vma can not be NULL, remove this check and simplify the code.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2014-10-09 15:27:48 -07:00 • committed by Linus Torvalds
commit 6b6482bbf6
3 changed files with 13 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

2
include/linux/mempolicy.h
View file

@ -136,7 +136,7 @@ struct mempolicy *mpol_shared_policy_lookup(struct shared_policy *sp,
struct mempolicy *get_vma_policy(struct task_struct *tsk,
struct vm_area_struct *vma, unsigned long addr);
bool vma_policy_mof(struct task_struct *task, struct vm_area_struct *vma);
bool vma_policy_mof(struct vm_area_struct *vma);
extern void numa_default_policy(void);
extern void numa_policy_init(void);

2
kernel/sched/fair.c
View file

@ -1946,7 +1946,7 @@ void task_numa_work(struct callback_head *work)
vma = mm->mmap;
}
for (; vma; vma = vma->vm_next) {
if (!vma_migratable(vma) || !vma_policy_mof(p, vma))
if (!vma_migratable(vma) || !vma_policy_mof(vma))
continue;
/*

9
mm/mempolicy.c
View file

@ -1646,11 +1646,10 @@ struct mempolicy *get_vma_policy(struct task_struct *task,
return pol;
}
bool vma_policy_mof(struct task_struct *task, struct vm_area_struct *vma)
bool vma_policy_mof(struct vm_area_struct *vma)
{
struct mempolicy *pol = NULL;
struct mempolicy *pol;
if (vma) {
if (vma->vm_ops && vma->vm_ops->get_policy) {
bool ret = false;
@ -1663,10 +1662,8 @@ bool vma_policy_mof(struct task_struct *task, struct vm_area_struct *vma)
}
pol = vma->vm_policy;
}
if (!pol)
pol = get_task_policy(task);
pol = get_task_policy(current);
return pol->flags & MPOL_F_MOF;
}