Commit 08270807 authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds

mm: revert 0def08e3 ("mm/mempolicy.c: check return code of check_range")

Revert commit 0def08e3 because check_range can't fail in
migrate_to_node with considering current usecases.

Quote from Johannes

: I think it makes sense to revert.  Not because of the semantics, but I
: just don't see how check_range() could even fail for this callsite:
: 1. we pass mm->mmap->vm_start in there, so we should not fail due to
:    find_vma()
: 2. we pass MPOL_MF_DISCONTIG_OK, so the discontig checks do not apply
:    and so can not fail
: 3. we pass MPOL_MF_MOVE | MPOL_MF_MOVE_ALL, the page table loops will
:    continue until addr == end, so we never fail with -EIO

And I added a new VM_BUG_ON for checking migrate_to_node's future usecase
which might pass to MPOL_MF_STRICT.
Suggested-by: default avatarJohannes Weiner <>
Signed-off-by: default avatarMinchan Kim <>
Acked-by: default avatarKOSAKI Motohiro <>
Cc: Mel Gorman <>
Cc: Christoph Lameter <>
Cc: David Rientjes <>
Cc: Vasiliy Kulikov <>
Acked-by: default avatarJohannes Weiner <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 6bdb913f
......@@ -946,15 +946,18 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
nodemask_t nmask;
int err = 0;
struct vm_area_struct *vma;
node_set(source, nmask);
vma = check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
* This does not "check" the range but isolates all pages that
* need migration. Between passing in the full user address
* space range and MPOL_MF_DISCONTIG_OK, this call can not fail.
check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
flags | MPOL_MF_DISCONTIG_OK, &pagelist);
if (IS_ERR(vma))
return PTR_ERR(vma);
if (!list_empty(&pagelist)) {
err = migrate_pages(&pagelist, new_node_page, dest,
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