mm, isolation: avoid checking unmovable pages across pageblock boundary
authorLi Xinhai <lixinhai.lxh@gmail.com>
Tue, 13 Oct 2020 23:55:39 +0000 (16:55 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 14 Oct 2020 01:38:33 +0000 (18:38 -0700)
commit6a654e36fa51a4ae1f109b0b30a23d3f097b3d8a
treeb4938765fbf634e41ebfb6fbe4dd2fe2878fcaf8
parent9181a980625a45425085ccec0fc38074a16470a5
mm, isolation: avoid checking unmovable pages across pageblock boundary

In has_unmovable_pages(), the page parameter would not always be the first
page within a pageblock (see how the page pointer is passed in from
start_isolate_page_range() after call __first_valid_page()), so that would
cause checking unmovable pages span two pageblocks.

After this patch, the checking is enforced within one pageblock no matter
the page is first one or not, and obey the semantics of this function.

This issue is found by code inspection.

Michal said "this might lead to false negatives when an unrelated block
would cause an isolation failure".

Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Link: https://lkml.kernel.org/r/20200824065811.383266-1-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/page_alloc.c