Christophe Leroy <christophe.leroy@xxxxxxxxxx> writes:
> Le 23/06/2022 à 14:29, Aneesh Kumar K.V a écrit :
>> Instead of high_memory use VMALLOC_START to validate that the address is
>> not in the vmalloc range.
>
> What's the reason for using VMALLOC_START instead ?
> The gap between high_memory and VMALLOC_START should not be seen as
> valid memory either, should it ?
Yes and that invalid range should be captured by the pfn_valid check.
Commit ffa0b64e3be5 intended to skip the vmalloc range.
Unfortunately, that resulted in kernel crash due to architecture not
updating high_memory after a memory hotplug. That should be fixed by
patch 1 in this series. patch 3 was added merely as a cleanup to
switch from high_memory to a more familiar VMALLOC_START variable.
>
> If the problem is book3s/64, commit ffa0b64e3be5 ("powerpc: Fix
> virt_addr_valid() for 64-bit Book3E & 32-bit") says that those
> additional tests are superfluous for boo3s/64. Maybe it's time to drop
> unnecessary tests for book3s/64 ?
They are not specific book3s/64. IIUC virt_addr_valid will return false
for an addr after memory hotplug on other platforms too. Patch 1
describe those details.
>
>>
>> Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
>> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
>> ---
>> arch/powerpc/include/asm/page.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
>> index e5f75c70eda8..256cad69e42e 100644
>> --- a/arch/powerpc/include/asm/page.h
>> +++ b/arch/powerpc/include/asm/page.h
>> @@ -134,7 +134,7 @@ static inline bool pfn_valid(unsigned long pfn)
>>
>> #define virt_addr_valid(vaddr) ({ \
>> unsigned long _addr = (unsigned long)vaddr; \
>> - _addr >= PAGE_OFFSET && _addr < (unsigned long)high_memory && \
>> + _addr >= PAGE_OFFSET && _addr < (unsigned long)VMALLOC_START && \
>> pfn_valid(virt_to_pfn(_addr)); \
>> })
>>
