Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

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

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 <hannes@cmpxchg.org>
Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Acked-by: default avatarKOSAKI 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: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6bdb913f

mm/mempolicy.c

+7 −4
Original line number Diff line number Diff line
@@ -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,