From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Subject: mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified
When MPOL_MF_STRICT was specified and an existing page was already on a
node that does not follow the policy, mbind() should return -EIO. But
6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()")
broke the rule.
And c8633798497c ("mm: mempolicy: mbind and migrate_pages support thp
migration") didn't return the correct value for THP mbind() too.
If MPOL_MF_STRICT is set, ignore vma_migratable() to make sure it reaches
queue_pages_to_pte_range() or queue_pages_pmd() to check if an existing
page was already on a node that does not follow the policy. And,
non-migratable vma may be used, return -EIO too if MPOL_MF_MOVE or
MPOL_MF_MOVE_ALL was specified.
Tested with https://github.com/metan-ucw/ltp/blob/master/testcases/kernel/syscalls/mbind/mbind02.c
[akpm@xxxxxxxxxxxxxxxxxxxx: tweak code comment]
Link: http://lkml.kernel.org/r/1553020556-38583-1-git-send-email-yang.shi@xxxxxxxxxxxxxxxxx
Fixes: 6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()")
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Reported-by: Cyril Hrubis <chrubis@xxxxxxx>
Suggested-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Acked-by: Rafael Aquini <aquini@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 40 +++++++++++++++++++++++++++++++++-------
1 file changed, 33 insertions(+), 7 deletions(-)
--- a/mm/mempolicy.c~mm-mempolicy-make-mbind-return-eio-when-mpol_mf_strict-is-specified
+++ a/mm/mempolicy.c
@@ -428,6 +428,13 @@ static inline bool queue_pages_required(
return node_isset(nid, *qp->nmask) == !(flags & MPOL_MF_INVERT);
}
+/*
+ * queue_pages_pmd() has three possible return values:
+ * 1 - pages are placed on the right node or queued successfully.
+ * 0 - THP was split.
+ * -EIO - is migration entry or MPOL_MF_STRICT was specified and an existing
+ * page was already on a node that does not follow the policy.
+ */
static int queue_pages_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
@@ -437,7 +444,7 @@ static int queue_pages_pmd(pmd_t *pmd, s
unsigned long flags;
if (unlikely(is_pmd_migration_entry(*pmd))) {
- ret = 1;
+ ret = -EIO;
goto unlock;
}
page = pmd_page(*pmd);
@@ -454,8 +461,15 @@ static int queue_pages_pmd(pmd_t *pmd, s
ret = 1;
flags = qp->flags;
/* go to thp migration */
- if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+ if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+ if (!vma_migratable(walk->vma)) {
+ ret = -EIO;
+ goto unlock;
+ }
+
migrate_page_add(page, qp->pagelist, flags);
+ } else
+ ret = -EIO;
unlock:
spin_unlock(ptl);
out:
@@ -480,8 +494,10 @@ static int queue_pages_pte_range(pmd_t *
ptl = pmd_trans_huge_lock(pmd, vma);
if (ptl) {
ret = queue_pages_pmd(pmd, ptl, addr, end, walk);
- if (ret)
+ if (ret > 0)
return 0;
+ else if (ret < 0)
+ return ret;
}
if (pmd_trans_unstable(pmd))
@@ -502,11 +518,16 @@ static int queue_pages_pte_range(pmd_t *
continue;
if (!queue_pages_required(page, qp))
continue;
- migrate_page_add(page, qp->pagelist, flags);
+ if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+ if (!vma_migratable(vma))
+ break;
+ migrate_page_add(page, qp->pagelist, flags);
+ } else
+ break;
}
pte_unmap_unlock(pte - 1, ptl);
cond_resched();
- return 0;
+ return addr != end ? -EIO : 0;
}
static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
@@ -576,7 +597,12 @@ static int queue_pages_test_walk(unsigne
unsigned long endvma = vma->vm_end;
unsigned long flags = qp->flags;
- if (!vma_migratable(vma))
+ /*
+ * Need check MPOL_MF_STRICT to return -EIO if possible
+ * regardless of vma_migratable
+ */
+ if (!vma_migratable(vma) &&
+ !(flags & MPOL_MF_STRICT))
return 1;
if (endvma > end)
@@ -603,7 +629,7 @@ static int queue_pages_test_walk(unsigne
}
/* queue pages from current vma */
- if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+ if (flags & MPOL_MF_VALID)
return 0;
return 1;
}
_
