2021-10-12 10:42:50

by Christophe Leroy

Subject: [PATCH] powerpc: Set max_mapnr correctly

max_mapnr is used by virt_addr_valid() to check if a linear
address is valid.

It must only include lowmem PFNs, like other architectures.

Problem detected on a system with 1G mem (Only 768M are mapped), with
CONFIG_DEBUG_VIRTUAL and CONFIG_TEST_DEBUG_VIRTUAL, it didn't report
virt_to_phys(VMALLOC_START), VMALLOC_START being 0xf1000000.

Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/mm/mem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index c3c4e31462ec..889f36b55df9 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -256,7 +256,7 @@ void __init mem_init(void)
#endif

high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
- set_max_mapnr(max_pfn);
+ set_max_mapnr(max_low_pfn);

kasan_late_init();

--
2.31.1

2021-10-18 03:44:53

by Michael Ellerman

Subject: Re: [PATCH] powerpc: Set max_mapnr correctly

On Tue, 12 Oct 2021 12:40:37 +0200, Christophe Leroy wrote:
> max_mapnr is used by virt_addr_valid() to check if a linear
> address is valid.
>
> It must only include lowmem PFNs, like other architectures.
>
> Problem detected on a system with 1G mem (Only 768M are mapped), with
> CONFIG_DEBUG_VIRTUAL and CONFIG_TEST_DEBUG_VIRTUAL, it didn't report
> virt_to_phys(VMALLOC_START), VMALLOC_START being 0xf1000000.
>
> [...]

Applied to powerpc/next.

[1/1] powerpc: Set max_mapnr correctly
https://git.kernel.org/powerpc/c/602946ec2f90d5bd965857753880db29d2d9a1e9

cheers