Checking unmapped hole and updating the previous vma must be handled first,
otherwise the unmapped hole could be calculated from a wrong previous vma.
Several commits were relevant to this error:
commit 6f4576e3687b
("mempolicy: apply page table walker on queue_pages_range()"),
This commit was correct, the VM_PFNMAP check was after updateing previous
vma
commit 48684a65b4e3
(mm: pagewalk: fix misbehavior of walk_page_range for vma(VM_PFNMAP)),
This commit added VM_PFNMAP check before updateing previous vma. Then,
there were two VM_PFNMAP check did same thing twice.
commit acda0c334028
(mm/mempolicy.c: get rid of duplicated check for vma(VM_PFNMAP) in queue_page
s_range()),
This commit tried to fix the duplicated VM_PFNMAP check, but it wrongly
removed the one which was after updateing vma.
Fixes: acda0c334028 (mm/mempolicy.c: get rid of duplicated check for vma(VM_PFNMAP) in queue_page
s_range())
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: linux-man <linux-man@xxxxxxxxxxxxxxx>
Signed-off-by: Li Xinhai <lixinhai.lxh@xxxxxxxxx>
---
mm/mempolicy.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4ae967b..807f06f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -618,6 +618,16 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
unsigned long endvma = vma->vm_end;
unsigned long flags = qp->flags;
+ /* range check first */
+ if (!(flags & MPOL_MF_DISCONTIG_OK)) {
+ if (!vma->vm_next && vma->vm_end < end)
+ return -EFAULT;
+ if (qp->prev && qp->prev->vm_end < vma->vm_start)
+ return -EFAULT;
+ }
+
+ qp->prev = vma;
+
/*
* Need check MPOL_MF_STRICT to return -EIO if possible
* regardless of vma_migratable
@@ -631,15 +641,6 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
if (vma->vm_start > start)
start = vma->vm_start;
- if (!(flags & MPOL_MF_DISCONTIG_OK)) {
- if (!vma->vm_next && vma->vm_end < end)
- return -EFAULT;
- if (qp->prev && qp->prev->vm_end < vma->vm_start)
- return -EFAULT;
- }
-
- qp->prev = vma;
-
if (flags & MPOL_MF_LAZY) {
/* Similar to task_numa_work, skip inaccessible VMAs */
if (!is_vm_hugetlb_page(vma) &&
--
1.8.3.1
