On 01.03.22 17:30, Felix Kuehling wrote:
Am 2022-03-01 um 11:22 schrieb David Hildenbrand:
if (PageReserved(page))diff --git a/mm/migrate.c b/mm/migrate.c index c31d04b46a5e..17d049311b78 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1614,7 +1614,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, goto out;
/* FOLL_DUMP to ignore special (like zero) pages */
- follflags = FOLL_GET | FOLL_DUMP;
- follflags = FOLL_GET | FOLL_DUMP | FOLL_LRU; page = follow_page(vma, addr, follflags);
Why wouldn't we want to dump DEVICE_COHERENT pages? This looks wrong.
This function later calls isolate_lru_page, which is something you can't do with a device page.
Then, that code might require care instead. We most certainly don't want to have random memory holes in a dump just because some anonymous memory was migrated to DEVICE_COHERENT.
I don't think this code is for core dumps. The call chain I see is
SYSCALL_DEFINE6(move_pages, ...) -> kernel_move_pages -> do_pages_move -> add_page_for_migration
Ah, sorry, I got mislead by FOLL_DUMP and thought we'd be in get_dump_page() . As you said, nothing to do.