Commit cc00550b authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Heiko Carstens
Browse files

Revert "s390/mm: Allow large pages for KASAN shadow mapping" 



This reverts commit ff123eb7.

Allowing large pages for KASAN shadow mappings isn't inherently wrong,
but adding POPULATE_KASAN_MAP_SHADOW to large_allowed() exposes an issue
in can_large_pud() and can_large_pmd().

Since commit d8073dc6 ("s390/mm: Allow large pages only for aligned
physical addresses"), both can_large_pud() and can_large_pmd() call _pa()
to check if large page physical addresses are aligned. However, _pa()
has a side effect: it allocates memory in POPULATE_KASAN_MAP_SHADOW
mode. This results in massive memory leaks.

The proper fix would be to address both large_allowed() and _pa()'s side
effects, but for now, revert this change to avoid the leaks.

Fixes: ff123eb7 ("s390/mm: Allow large pages for KASAN shadow mapping")
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 889221c4

arch/s390/boot/vmem.c

+1 −11
Original line number Diff line number Diff line
@@ -264,17 +264,7 @@ static unsigned long _pa(unsigned long addr, unsigned long size, enum populate_m 


static bool large_allowed(enum populate_mode mode)

{

	switch (mode) {

	case POPULATE_DIRECT:

	case POPULATE_IDENTITY:

	case POPULATE_KERNEL:

#ifdef CONFIG_KASAN

	case POPULATE_KASAN_MAP_SHADOW:

#endif

		return true;

	default:

		return false;

	}

	return (mode == POPULATE_DIRECT) || (mode == POPULATE_IDENTITY) || (mode == POPULATE_KERNEL);

}



static bool can_large_pud(pud_t *pu_dir, unsigned long addr, unsigned long end,