2023-11-15 20:36:16

by Ilya Leoshkevich

Subject: [PATCH 03/32] kmsan: Disable KMSAN when DEFERRED_STRUCT_PAGE_INIT is enabled

KMSAN relies on memblock returning all available pages to it
(see kmsan_memblock_free_pages()). It partitions these pages into 3
categories: pages available to the buddy allocator, shadow pages and
origin pages. This partitioning is static.

If new pages appear after kmsan_init_runtime(), it is considered
an error. DEFERRED_STRUCT_PAGE_INIT causes this, so mark it as
incompatible with KMSAN.

Signed-off-by: Ilya Leoshkevich <[email protected]>
---
mm/Kconfig | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index 89971a894b60..4f2f99339fc7 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -985,6 +985,7 @@ config DEFERRED_STRUCT_PAGE_INIT
depends on SPARSEMEM
depends on !NEED_PER_CPU_KM
depends on 64BIT
+ depends on !KMSAN
select PADATA
help
Ordinarily all struct pages are initialised during early boot in a
--
2.41.0

2023-11-16 09:42:21

by Alexander Potapenko

Subject: Re: [PATCH 03/32] kmsan: Disable KMSAN when DEFERRED_STRUCT_PAGE_INIT is enabled

On Wed, Nov 15, 2023 at 9:34 PM Ilya Leoshkevich <[email protected]> wrote:
>
> KMSAN relies on memblock returning all available pages to it
> (see kmsan_memblock_free_pages()). It partitions these pages into 3
> categories: pages available to the buddy allocator, shadow pages and
> origin pages. This partitioning is static.
>
> If new pages appear after kmsan_init_runtime(), it is considered
> an error. DEFERRED_STRUCT_PAGE_INIT causes this, so mark it as
> incompatible with KMSAN.

In the future we could probably collect the deferred pages as well,
but it's okay to disable KMSAN for now.

> Signed-off-by: Ilya Leoshkevich <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>