From 082708072a4250f5c4dbc62065e7af93f5e45646 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 8 Oct 2012 16:33:38 -0700 Subject: [PATCH] mm: revert 0def08e3 ("mm/mempolicy.c: check return code of check_range") 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 Signed-off-by: Minchan Kim Acked-by: KOSAKI Motohiro Cc: Mel Gorman Cc: Christoph Lameter Cc: David Rientjes Cc: Vasiliy Kulikov Acked-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mempolicy.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 3d64b369180d..0b78fb9ea65b 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -946,15 +946,18 @@ 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, -- 2.39.5