From: Michal Hocko <mhocko@xxxxxxxx>
set_mempolicy_home_node tries to duplicate a memory policy before
checking it whether it is applicable for the operation. There is
no real reason for doing that and it might actually be a pointless
memory allocation and deallocation exercise for MPOL_INTERLEAVE.
Not a big problem but we can do better. Simply check the policy before
acting on it.
[ Mathieu: compile-tested only. Tested-by would be welcome. ]
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Feng Tang <feng.tang@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: linux-api@xxxxxxxxxxxxxxx
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
mm/mempolicy.c | 28 ++++++++++++----------------
1 file changed, 12 insertions(+), 16 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 02c8a712282f..becf41e10076 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1489,7 +1489,7 @@ SYSCALL_DEFINE4(set_mempolicy_home_node, unsigned long, start, unsigned long, le
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
- struct mempolicy *new;
+ struct mempolicy *new, *old;
unsigned long vmstart;
unsigned long vmend;
unsigned long end;
@@ -1521,31 +1521,27 @@ SYSCALL_DEFINE4(set_mempolicy_home_node, unsigned long, start, unsigned long, le
return 0;
mmap_write_lock(mm);
for_each_vma_range(vmi, vma, end) {
- vmstart = max(start, vma->vm_start);
- vmend = min(end, vma->vm_end);
- new = mpol_dup(vma_policy(vma));
- if (IS_ERR(new)) {
- err = PTR_ERR(new);
- break;
- }
- /*
- * Only update home node if there is an existing vma policy
- */
- if (!new)
- continue;
-
/*
* If any vma in the range got policy other than MPOL_BIND
* or MPOL_PREFERRED_MANY we return error. We don't reset
* the home node for vmas we already updated before.
*/
- if (new->mode != MPOL_BIND && new->mode != MPOL_PREFERRED_MANY) {
- mpol_put(new);
+ old = vma_policy(vma);
+ if (!old)
+ continue;
+ if (old->mode != MPOL_BIND && old->mode != MPOL_PREFERRED_MANY) {
err = -EOPNOTSUPP;
break;
}
+ new = mpol_dup(old);
+ if (IS_ERR(new)) {
+ err = PTR_ERR(new);
+ break;
+ }
new->home_node = home_node;
+ vmstart = max(start, vma->vm_start);
+ vmend = min(end, vma->vm_end);
err = mbind_range(mm, vmstart, vmend, new);
mpol_put(new);
if (err)
--
2.25.1
