From 8d90274b3b118c9babeefb1302947f33a1364fb5 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Thu, 9 Oct 2014 15:27:45 -0700
Subject: [PATCH] mempolicy: sanitize the usage of get_task_policy()
Cleanup + preparation. Every user of get_task_policy() calls it
unconditionally, even if it is not going to use the result.
get_task_policy() is cheap but still this does not look clean, plus
the code looks simpler if get_task_policy() is called only when this
is really needed.
Note: I hope this is correct, but it is not clear why vma_policy_mof()
doesn't fall back to get_task_policy() if ->get_policy() returns NULL.
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>
---
mm/mempolicy.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 656db97584f05..b86b08e77b8d0 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1621,14 +1621,11 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
struct mempolicy *get_vma_policy(struct task_struct *task,
struct vm_area_struct *vma, unsigned long addr)
{
- struct mempolicy *pol = get_task_policy(task);
+ struct mempolicy *pol = NULL;
if (vma) {
if (vma->vm_ops && vma->vm_ops->get_policy) {
- struct mempolicy *vpol = vma->vm_ops->get_policy(vma,
- addr);
- if (vpol)
- pol = vpol;
+ pol = vma->vm_ops->get_policy(vma, addr);
} else if (vma->vm_policy) {
pol = vma->vm_policy;
@@ -1643,12 +1640,15 @@ struct mempolicy *get_vma_policy(struct task_struct *task,
}
}
+ if (!pol)
+ pol = get_task_policy(task);
+
return pol;
}
bool vma_policy_mof(struct task_struct *task, struct vm_area_struct *vma)
{
- struct mempolicy *pol = get_task_policy(task);
+ struct mempolicy *pol = NULL;
if (vma) {
if (vma->vm_ops && vma->vm_ops->get_policy) {
@@ -1660,11 +1660,14 @@ bool vma_policy_mof(struct task_struct *task, struct vm_area_struct *vma)
mpol_cond_put(pol);
return ret;
- } else if (vma->vm_policy) {
- pol = vma->vm_policy;
}
+
+ pol = vma->vm_policy;
}
+ if (!pol)
+ pol = get_task_policy(task);
+
return pol->flags & MPOL_F_MOF;
}
@@ -2068,12 +2071,12 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
*/
struct page *alloc_pages_current(gfp_t gfp, unsigned order)
{
- struct mempolicy *pol = get_task_policy(current);
+ struct mempolicy *pol = &default_policy;
struct page *page;
unsigned int cpuset_mems_cookie;
- if (in_interrupt() || (gfp & __GFP_THISNODE))
- pol = &default_policy;
+ if (!in_interrupt() && !(gfp & __GFP_THISNODE))
+ pol = get_task_policy(current);
retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();
--
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