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. -- Thanks, David / dhildenb
