From 6b6482bbf64ef6f6dbc8b52f7a7cf88a0498bd51 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Thu, 9 Oct 2014 15:27:48 -0700
Subject: [PATCH] mempolicy: remove the "task" arg of vma_policy_mof() and
simplify it
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>
---
include/linux/mempolicy.h | 2 +-
kernel/sched/fair.c | 2 +-
mm/mempolicy.c | 25 +++++++++++--------------
3 files changed, 13 insertions(+), 16 deletions(-)
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index f230a978e6baf..5e4bfcedd2cee 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -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);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bfa3c86d0d686..82088b29704ef 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -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;
/*
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index b86b08e77b8d0..ad27bbc757bf0 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1646,27 +1646,24 @@ 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;
-
- if (vma) {
- if (vma->vm_ops && vma->vm_ops->get_policy) {
- bool ret = false;
+ struct mempolicy *pol;
- pol = vma->vm_ops->get_policy(vma, vma->vm_start);
- if (pol && (pol->flags & MPOL_F_MOF))
- ret = true;
- mpol_cond_put(pol);
+ if (vma->vm_ops && vma->vm_ops->get_policy) {
+ bool ret = false;
- return ret;
- }
+ pol = vma->vm_ops->get_policy(vma, vma->vm_start);
+ if (pol && (pol->flags & MPOL_F_MOF))
+ ret = true;
+ mpol_cond_put(pol);
- pol = vma->vm_policy;
+ return ret;
}
+ pol = vma->vm_policy;
if (!pol)
- pol = get_task_policy(task);
+ pol = get_task_policy(current);
return pol->flags & MPOL_F_MOF;
}
--
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