aboutsummaryrefslogtreecommitdiffstats
path: root/mm/mempolicy.c
diff options
context:
space:
mode:
authorLi Xinhai <lixinhai.lxh@gmail.com>2019-11-30 17:56:15 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-01 12:59:07 -0800
commita18b3ac25bb7be4781cb9e6d31f3e57b3ba01b06 (patch)
tree013df8e29c47e0f19d2679f0c9c64999cecac663 /mm/mempolicy.c
parentmm/z3fold.c: add inter-page compaction (diff)
downloadlinux-dev-a18b3ac25bb7be4781cb9e6d31f3e57b3ba01b06.tar.xz
linux-dev-a18b3ac25bb7be4781cb9e6d31f3e57b3ba01b06.zip
mm/mempolicy.c: check range first in queue_pages_test_walk
Patch series "mm: Fix checking unmapped holes for mbind", v4. This patchset fix checking unmapped holes for mbind(). First patch makes sure the vma been correctly tracked in .test_walk(), so each time when .test_walk() is called, the neighborhood of two vma is correct. Current problem is that the !vma_migratable() check could cause return immediately without update tracking to vma. Second patch fix the inconsistent report of EFAULT when mbind() is called for MPOL_DEFAULT and non MPOL_DEFAULT cases, so application do not need to have workaround code to handle this special behavior. Currently there are two problems, one is that the .test_walk() can not know there is hole at tail side of range, because .test_walk() only call for vma not for hole. The other one is that mbind_range() checks for hole at head side of range but do not consider the MPOL_MF_DISCONTIG_OK flag as done in .test_walk(). This patch (of 2): 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 updating previous vma - commit 48684a65b4e3 ("mm: pagewalk: fix misbehavior of walk_page_range for vma(VM_PFNMAP)") This commit added VM_PFNMAP check before updating 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 updating vma. Link: http://lkml.kernel.org/r/1573218104-11021-2-git-send-email-lixinhai.lxh@gmail.com Fixes: acda0c334028 (mm/mempolicy.c: get rid of duplicated check for vma(VM_PFNMAP) in queue_pages_range()) Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: linux-man <linux-man@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
-rw-r--r--mm/mempolicy.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e08c94170ae4..2192b16bbcff 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) &&