mm/page_isolation: guard against possible putback unisolated page

Isolating a free page in an isolated pageblock is expected to always
work as watermarks don't apply here.

But if __isolate_free_page() failed, due to condition changes, the page
will be left on the free list.  And the page will be put back to free
list again via __putback_isolated_page().  This may trigger
VM_BUG_ON_PAGE() on page->flags checking in __free_one_page() if
PageReported is set.  Or we will corrupt the free list because
list_add() will be called for pages already on another list.

Add a VM_WARN_ON() to complain about this change.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions