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authorMinchan Kim <minchan@kernel.org>2012-10-08 16:33:38 -0700
committerBen Hutchings <ben@decadent.org.uk>2014-07-11 13:33:54 +0100
commit386292b433495a8dfc5c2991145943d97e559fff (patch)
tree2bba96bcddc3174fd7507b88ef566f5f5f356c1e
parentde5f02d08d32aaf559f57def64176dae52a2e00a (diff)
mm: revert 0def08e3 ("mm/mempolicy.c: check return code of check_range")
commit 082708072a4250f5c4dbc62065e7af93f5e45646 upstream. Revert commit 0def08e3acc2 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: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vasiliy Kulikov <segooon@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r--mm/mempolicy.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4d1e63741bf4..388ac0724c6b 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -945,15 +945,18 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
nodemask_t nmask;
LIST_HEAD(pagelist);
int err = 0;
- struct vm_area_struct *vma;
nodes_clear(nmask);
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.
+ */
+ VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)));
+ 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,