From cc00550b2ae7ab1c7c56669fc004a13d880aaf0a Mon Sep 17 00:00:00 2001
From: Vasily Gorbik <gor@linux.ibm.com>
Date: Fri, 29 Nov 2024 01:07:01 +0100
Subject: [PATCH] Revert "s390/mm: Allow large pages for KASAN shadow mapping"
This reverts commit ff123eb7741638d55abf82fac090bb3a543c1e74.
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 d8073dc6bc04 ("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: ff123eb77416 ("s390/mm: Allow large pages for KASAN shadow mapping")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
arch/s390/boot/vmem.c | 12 +-----------
1 file changed, 1 insertion(+), 11 deletions(-)
diff --git a/arch/s390/boot/vmem.c b/arch/s390/boot/vmem.c
index 8476b6f965a92..145035f84a0e3 100644
--- a/arch/s390/boot/vmem.c
+++ b/arch/s390/boot/vmem.c
@@ -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,
--
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