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
As far as I can tell this is for NUMA migrations.
Regards,
Felix
