Michael Neuling <mi...@neuling.org> writes:
> Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> wrote:
>
>> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
>>
>> Book3E uses the hugepd at PMD level and don't encode pte directly
>> at the pmd level. So it will find the lower bits of pmd set
>> and the pmd_bad check throws error. Infact the current code
>> will never take the free_hugepd_range call at all because it will
>> clear the pmd if it find a hugepd pointer.
>>
>
> Please explain what changes you are making. Currently you are only
> describing what the issue is.
will do
>
> Also include which the SHA1 which caused the regression (ie
> e2b3d202d1dba8f3546ed28224ce485bc50010be "powerpc: Switch 16GB and 16MB
> explicit hugepages to a different page table format")
will add
>
> Mikey
>
>> Reported-by: Scott Wood <scottw...@freescale.com>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
>> ---
>> arch/powerpc/mm/hugetlbpage.c | 29 ++++++++++++++++++-----------
>> 1 file changed, 18 insertions(+), 11 deletions(-)
>>
>> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
>> index f2f01fd..0d3d3ee 100644
>> --- a/arch/powerpc/mm/hugetlbpage.c
>> +++ b/arch/powerpc/mm/hugetlbpage.c
>> @@ -536,19 +536,26 @@ static void hugetlb_free_pmd_range(struct mmu_gather
>> *tlb, pud_t *pud,
>> do {
>> pmd = pmd_offset(pud, addr);
>> next = pmd_addr_end(addr, end);
>> - if (pmd_none_or_clear_bad(pmd))
>> - continue;
>> + if (!is_hugepd(pmd)) {
>> + /*
>> + * if it is not hugepd pointer, we should already find
>> + * it cleared.
>> + */
>> + if (!pmd_none_or_clear_bad(pmd))
>> + WARN_ON(1);
>
> How often are we going to hit this? Should this be a warn_on once or
> even a bug_on?
it should never happen. But i was thinking killing the system may a bit
too much, hence WARN_ON
>
> Also just make it:
> WARN_ON(!pmd_none_or_clear_bad(pmd))
>
will do
-aneesh
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