Re: [PATCH] mm/debug_vm_pgtable: Fix BUG_ON with pud advanced test

2024-02-19 Thread Aneesh Kumar K.V 
On 2/20/24 8:16 AM, Andrew Morton wrote:
> On Mon, 29 Jan 2024 13:43:39 +0530 "Aneesh Kumar K.V" 
>  wrote:
> 
>>> return (pud_val(pud) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
>>> }
>>> #endif
>>>
>>> #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
>>> static inline int pud_devmap(pud_t pud)
>>> {
>>> return !!(pud_val(pud) & _PAGE_DEVMAP);
>>> }
>>> #else
>>> static inline int pud_devmap(pud_t pud)
>>> {
>>> return 0;
>>> }
>>> #endif
>>>
>>> We might need some more clarity on this regarding x86 platform's pud huge
>>> page implementation.
>>>
>>
>> static vm_fault_t create_huge_pud(struct vm_fault *vmf)
>> {
>> #if defined(CONFIG_TRANSPARENT_HUGEPAGE) &&  \
>>  defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
>>  struct vm_area_struct *vma = vmf->vma;
>>  /* No support for anonymous transparent PUD pages yet */
>>  if (vma_is_anonymous(vma))
>>  return VM_FAULT_FALLBACK;
>>  if (vma->vm_ops->huge_fault)
>>  return vma->vm_ops->huge_fault(vmf, PUD_ORDER);
>> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>>  return VM_FAULT_FALLBACK;
>> }
> 
> cryptic reply, unreplied to.
> 
> What's the thinking here?  Should we proceed with the patch as-is, or
> are changes needed?
> 

Sorry for the confusion. What i wanted to update with the code was to reiterate
that no architectures currently does anonymous pud hugepage. So restricting
debug_vm_pgtable pud hugepage test to devmap pte entries should be ok w.r.t
these tests.

-aneesh

Re: [PATCH] mm/debug_vm_pgtable: Fix BUG_ON with pud advanced test

2024-02-19 Thread Andrew Morton 
On Mon, 29 Jan 2024 13:43:39 +0530 "Aneesh Kumar K.V"  
wrote:

> > return (pud_val(pud) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
> > }
> > #endif
> > 
> > #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> > static inline int pud_devmap(pud_t pud)
> > {
> > return !!(pud_val(pud) & _PAGE_DEVMAP);
> > }
> > #else
> > static inline int pud_devmap(pud_t pud)
> > {
> > return 0;
> > }
> > #endif
> > 
> > We might need some more clarity on this regarding x86 platform's pud huge
> > page implementation.
> > 
> 
> static vm_fault_t create_huge_pud(struct vm_fault *vmf)
> {
> #if defined(CONFIG_TRANSPARENT_HUGEPAGE) &&   \
>   defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
>   struct vm_area_struct *vma = vmf->vma;
>   /* No support for anonymous transparent PUD pages yet */
>   if (vma_is_anonymous(vma))
>   return VM_FAULT_FALLBACK;
>   if (vma->vm_ops->huge_fault)
>   return vma->vm_ops->huge_fault(vmf, PUD_ORDER);
> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>   return VM_FAULT_FALLBACK;
> }

cryptic reply, unreplied to.

What's the thinking here?  Should we proceed with the patch as-is, or
are changes needed?

Re: [PATCH] mm/debug_vm_pgtable: Fix BUG_ON with pud advanced test

2024-01-29 Thread Aneesh Kumar K.V 
On 1/29/24 12:23 PM, Anshuman Khandual wrote:
> 
> 
> On 1/29/24 11:56, Aneesh Kumar K.V wrote:
>> On 1/29/24 11:52 AM, Anshuman Khandual wrote:
>>>
>>>
>>> On 1/29/24 11:30, Aneesh Kumar K.V (IBM) wrote:
 Architectures like powerpc add debug checks to ensure we find only devmap
 PUD pte entries. These debug checks are only done with CONFIG_DEBUG_VM.
 This patch marks the ptes used for PUD advanced test devmap pte entries
 so that we don't hit on debug checks on architecture like ppc64 as
 below.

 WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 
 radix__pud_hugepage_update+0x38/0x138
 
 NIP [c00a7004] radix__pud_hugepage_update+0x38/0x138
 LR [c00a77a8] radix__pudp_huge_get_and_clear+0x28/0x60
 Call Trace:
 [c4a2f950] [c4a2f9a0] 0xc4a2f9a0 (unreliable)
 [c4a2f980] [000d34c1] 0xd34c1
 [c4a2f9a0] [c206ba98] pud_advanced_tests+0x118/0x334
 [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
 [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388

 Also

  kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202!
  

  NIP [c0096510] pudp_huge_get_and_clear_full+0x98/0x174
  LR [c206bb34] pud_advanced_tests+0x1b4/0x334
  Call Trace:
  [c4a2f950] [000d34c1] 0xd34c1 (unreliable)
  [c4a2f9a0] [c206bb34] pud_advanced_tests+0x1b4/0x334
  [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
  [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388

 Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud 
 hugepage")
 Signed-off-by: Aneesh Kumar K.V (IBM) 
 ---
  mm/debug_vm_pgtable.c | 8 
  1 file changed, 8 insertions(+)

 diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
 index 5662e29fe253..65c19025da3d 100644
 --- a/mm/debug_vm_pgtable.c
 +++ b/mm/debug_vm_pgtable.c
 @@ -362,6 +362,12 @@ static void __init pud_advanced_tests(struct 
 pgtable_debug_args *args)
vaddr &= HPAGE_PUD_MASK;
  
pud = pfn_pud(args->pud_pfn, args->page_prot);
 +  /*
 +   * Some architectures have debug checks to make sure
 +   * huge pud mapping are only found with devmap entries
 +   * For now test with only devmap entries.
 +   */
>>> Do you see this behaviour to be changed in powerpc anytime soon ? Otherwise
>>> these pud_mkdevmap() based work arounds, might be required to stick around
>>> for longer just to prevent powerpc specific triggers. Given PUD transparent
>>> huge pages i.e HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD are just supported on x86
>>> and powerpc platforms, could not this problem be solved in a more uniform
>>> manner.
>>>
>>
>>
>> IIUC pud level transparent hugepages are only supported with devmap entries 
>> even
>> on x86. We don't do anonymous pud hugepage.
> 
> There are some 'pud_trans_huge(orig_pud) || pud_devmap(orig_pud)' checks in
> core paths i.e in mm/memory.c which might suggest pud_trans_huge() to exist
> without also being a devmap. I might be missing something here, but on x86
> platform following helpers suggest pud_trans_huge() to exist without being
> a devmap as well.
> 
> #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> static inline int pud_trans_huge(pud_t pud)
> {
> return (pud_val(pud) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
> }
> #endif
> 
> #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> static inline int pud_devmap(pud_t pud)
> {
> return !!(pud_val(pud) & _PAGE_DEVMAP);
> }
> #else
> static inline int pud_devmap(pud_t pud)
> {
> return 0;
> }
> #endif
> 
> We might need some more clarity on this regarding x86 platform's pud huge
> page implementation.
> 

static vm_fault_t create_huge_pud(struct vm_fault *vmf)
{
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
struct vm_area_struct *vma = vmf->vma;
/* No support for anonymous transparent PUD pages yet */
if (vma_is_anonymous(vma))
return VM_FAULT_FALLBACK;
if (vma->vm_ops->huge_fault)
return vma->vm_ops->huge_fault(vmf, PUD_ORDER);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
return VM_FAULT_FALLBACK;
}



-aneesh

Re: [PATCH] mm/debug_vm_pgtable: Fix BUG_ON with pud advanced test

2024-01-28 Thread Anshuman Khandual 



On 1/29/24 11:56, Aneesh Kumar K.V wrote:
> On 1/29/24 11:52 AM, Anshuman Khandual wrote:
>>
>>
>> On 1/29/24 11:30, Aneesh Kumar K.V (IBM) wrote:
>>> Architectures like powerpc add debug checks to ensure we find only devmap
>>> PUD pte entries. These debug checks are only done with CONFIG_DEBUG_VM.
>>> This patch marks the ptes used for PUD advanced test devmap pte entries
>>> so that we don't hit on debug checks on architecture like ppc64 as
>>> below.
>>>
>>> WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 
>>> radix__pud_hugepage_update+0x38/0x138
>>> 
>>> NIP [c00a7004] radix__pud_hugepage_update+0x38/0x138
>>> LR [c00a77a8] radix__pudp_huge_get_and_clear+0x28/0x60
>>> Call Trace:
>>> [c4a2f950] [c4a2f9a0] 0xc4a2f9a0 (unreliable)
>>> [c4a2f980] [000d34c1] 0xd34c1
>>> [c4a2f9a0] [c206ba98] pud_advanced_tests+0x118/0x334
>>> [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
>>> [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388
>>>
>>> Also
>>>
>>>  kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202!
>>>  
>>>
>>>  NIP [c0096510] pudp_huge_get_and_clear_full+0x98/0x174
>>>  LR [c206bb34] pud_advanced_tests+0x1b4/0x334
>>>  Call Trace:
>>>  [c4a2f950] [000d34c1] 0xd34c1 (unreliable)
>>>  [c4a2f9a0] [c206bb34] pud_advanced_tests+0x1b4/0x334
>>>  [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
>>>  [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388
>>>
>>> Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage")
>>> Signed-off-by: Aneesh Kumar K.V (IBM) 
>>> ---
>>>  mm/debug_vm_pgtable.c | 8 
>>>  1 file changed, 8 insertions(+)
>>>
>>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
>>> index 5662e29fe253..65c19025da3d 100644
>>> --- a/mm/debug_vm_pgtable.c
>>> +++ b/mm/debug_vm_pgtable.c
>>> @@ -362,6 +362,12 @@ static void __init pud_advanced_tests(struct 
>>> pgtable_debug_args *args)
>>> vaddr &= HPAGE_PUD_MASK;
>>>  
>>> pud = pfn_pud(args->pud_pfn, args->page_prot);
>>> +   /*
>>> +* Some architectures have debug checks to make sure
>>> +* huge pud mapping are only found with devmap entries
>>> +* For now test with only devmap entries.
>>> +*/
>> Do you see this behaviour to be changed in powerpc anytime soon ? Otherwise
>> these pud_mkdevmap() based work arounds, might be required to stick around
>> for longer just to prevent powerpc specific triggers. Given PUD transparent
>> huge pages i.e HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD are just supported on x86
>> and powerpc platforms, could not this problem be solved in a more uniform
>> manner.
>>
> 
> 
> IIUC pud level transparent hugepages are only supported with devmap entries 
> even
> on x86. We don't do anonymous pud hugepage.

There are some 'pud_trans_huge(orig_pud) || pud_devmap(orig_pud)' checks in
core paths i.e in mm/memory.c which might suggest pud_trans_huge() to exist
without also being a devmap. I might be missing something here, but on x86
platform following helpers suggest pud_trans_huge() to exist without being
a devmap as well.

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static inline int pud_trans_huge(pud_t pud)
{
return (pud_val(pud) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
}
#endif

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static inline int pud_devmap(pud_t pud)
{
return !!(pud_val(pud) & _PAGE_DEVMAP);
}
#else
static inline int pud_devmap(pud_t pud)
{
return 0;
}
#endif

We might need some more clarity on this regarding x86 platform's pud huge
page implementation.

> 
>>> +   pud = pud_mkdevmap(pud);
>>> set_pud_at(args->mm, vaddr, args->pudp, pud);
>>> flush_dcache_page(page);
>>> pudp_set_wrprotect(args->mm, vaddr, args->pudp);
>>> @@ -374,6 +380,7 @@ static void __init pud_advanced_tests(struct 
>>> pgtable_debug_args *args)
>>> WARN_ON(!pud_none(pud));
>>>  #endif /* __PAGETABLE_PMD_FOLDED */
>>> pud = pfn_pud(args->pud_pfn, args->page_prot);
>>> +   pud = pud_mkdevmap(pud);
>>> pud = pud_wrprotect(pud);
>>> pud = pud_mkclean(pud);
>>> set_pud_at(args->mm, vaddr, args->pudp, pud);
>>> @@ -391,6 +398,7 @@ static void __init pud_advanced_tests(struct 
>>> pgtable_debug_args *args)
>>>  #endif /* __PAGETABLE_PMD_FOLDED */
>>>  
>>> pud = pfn_pud(args->pud_pfn, args->page_prot);
>>> +   pud = pud_mkdevmap(pud);
>>> pud = pud_mkyoung(pud);
>>> set_pud_at(args->mm, vaddr, args->pudp, pud);
>>> flush_dcache_page(page);
> 
> 
> -aneesh
>

Re: [PATCH] mm/debug_vm_pgtable: Fix BUG_ON with pud advanced test

2024-01-28 Thread Anshuman Khandual 



On 1/29/24 11:30, Aneesh Kumar K.V (IBM) wrote:
> Architectures like powerpc add debug checks to ensure we find only devmap
> PUD pte entries. These debug checks are only done with CONFIG_DEBUG_VM.
> This patch marks the ptes used for PUD advanced test devmap pte entries
> so that we don't hit on debug checks on architecture like ppc64 as
> below.
> 
> WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 
> radix__pud_hugepage_update+0x38/0x138
> 
> NIP [c00a7004] radix__pud_hugepage_update+0x38/0x138
> LR [c00a77a8] radix__pudp_huge_get_and_clear+0x28/0x60
> Call Trace:
> [c4a2f950] [c4a2f9a0] 0xc4a2f9a0 (unreliable)
> [c4a2f980] [000d34c1] 0xd34c1
> [c4a2f9a0] [c206ba98] pud_advanced_tests+0x118/0x334
> [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
> [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388
> 
> Also
> 
>  kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202!
>  
> 
>  NIP [c0096510] pudp_huge_get_and_clear_full+0x98/0x174
>  LR [c206bb34] pud_advanced_tests+0x1b4/0x334
>  Call Trace:
>  [c4a2f950] [000d34c1] 0xd34c1 (unreliable)
>  [c4a2f9a0] [c206bb34] pud_advanced_tests+0x1b4/0x334
>  [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
>  [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388
> 
> Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage")
> Signed-off-by: Aneesh Kumar K.V (IBM) 
> ---
>  mm/debug_vm_pgtable.c | 8 
>  1 file changed, 8 insertions(+)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 5662e29fe253..65c19025da3d 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -362,6 +362,12 @@ static void __init pud_advanced_tests(struct 
> pgtable_debug_args *args)
>   vaddr &= HPAGE_PUD_MASK;
>  
>   pud = pfn_pud(args->pud_pfn, args->page_prot);
> + /*
> +  * Some architectures have debug checks to make sure
> +  * huge pud mapping are only found with devmap entries
> +  * For now test with only devmap entries.
> +  */
Do you see this behaviour to be changed in powerpc anytime soon ? Otherwise
these pud_mkdevmap() based work arounds, might be required to stick around
for longer just to prevent powerpc specific triggers. Given PUD transparent
huge pages i.e HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD are just supported on x86
and powerpc platforms, could not this problem be solved in a more uniform
manner.

> + pud = pud_mkdevmap(pud);
>   set_pud_at(args->mm, vaddr, args->pudp, pud);
>   flush_dcache_page(page);
>   pudp_set_wrprotect(args->mm, vaddr, args->pudp);
> @@ -374,6 +380,7 @@ static void __init pud_advanced_tests(struct 
> pgtable_debug_args *args)
>   WARN_ON(!pud_none(pud));
>  #endif /* __PAGETABLE_PMD_FOLDED */
>   pud = pfn_pud(args->pud_pfn, args->page_prot);
> + pud = pud_mkdevmap(pud);
>   pud = pud_wrprotect(pud);
>   pud = pud_mkclean(pud);
>   set_pud_at(args->mm, vaddr, args->pudp, pud);
> @@ -391,6 +398,7 @@ static void __init pud_advanced_tests(struct 
> pgtable_debug_args *args)
>  #endif /* __PAGETABLE_PMD_FOLDED */
>  
>   pud = pfn_pud(args->pud_pfn, args->page_prot);
> + pud = pud_mkdevmap(pud);
>   pud = pud_mkyoung(pud);
>   set_pud_at(args->mm, vaddr, args->pudp, pud);
>   flush_dcache_page(page);

Re: [PATCH] mm/debug_vm_pgtable: Fix BUG_ON with pud advanced test

2024-01-28 Thread Aneesh Kumar K.V 
On 1/29/24 11:52 AM, Anshuman Khandual wrote:
> 
> 
> On 1/29/24 11:30, Aneesh Kumar K.V (IBM) wrote:
>> Architectures like powerpc add debug checks to ensure we find only devmap
>> PUD pte entries. These debug checks are only done with CONFIG_DEBUG_VM.
>> This patch marks the ptes used for PUD advanced test devmap pte entries
>> so that we don't hit on debug checks on architecture like ppc64 as
>> below.
>>
>> WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 
>> radix__pud_hugepage_update+0x38/0x138
>> 
>> NIP [c00a7004] radix__pud_hugepage_update+0x38/0x138
>> LR [c00a77a8] radix__pudp_huge_get_and_clear+0x28/0x60
>> Call Trace:
>> [c4a2f950] [c4a2f9a0] 0xc4a2f9a0 (unreliable)
>> [c4a2f980] [000d34c1] 0xd34c1
>> [c4a2f9a0] [c206ba98] pud_advanced_tests+0x118/0x334
>> [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
>> [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388
>>
>> Also
>>
>>  kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202!
>>  
>>
>>  NIP [c0096510] pudp_huge_get_and_clear_full+0x98/0x174
>>  LR [c206bb34] pud_advanced_tests+0x1b4/0x334
>>  Call Trace:
>>  [c4a2f950] [000d34c1] 0xd34c1 (unreliable)
>>  [c4a2f9a0] [c206bb34] pud_advanced_tests+0x1b4/0x334
>>  [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
>>  [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388
>>
>> Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage")
>> Signed-off-by: Aneesh Kumar K.V (IBM) 
>> ---
>>  mm/debug_vm_pgtable.c | 8 
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
>> index 5662e29fe253..65c19025da3d 100644
>> --- a/mm/debug_vm_pgtable.c
>> +++ b/mm/debug_vm_pgtable.c
>> @@ -362,6 +362,12 @@ static void __init pud_advanced_tests(struct 
>> pgtable_debug_args *args)
>>  vaddr &= HPAGE_PUD_MASK;
>>  
>>  pud = pfn_pud(args->pud_pfn, args->page_prot);
>> +/*
>> + * Some architectures have debug checks to make sure
>> + * huge pud mapping are only found with devmap entries
>> + * For now test with only devmap entries.
>> + */
> Do you see this behaviour to be changed in powerpc anytime soon ? Otherwise
> these pud_mkdevmap() based work arounds, might be required to stick around
> for longer just to prevent powerpc specific triggers. Given PUD transparent
> huge pages i.e HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD are just supported on x86
> and powerpc platforms, could not this problem be solved in a more uniform
> manner.
> 


IIUC pud level transparent hugepages are only supported with devmap entries even
on x86. We don't do anonymous pud hugepage.

>> +pud = pud_mkdevmap(pud);
>>  set_pud_at(args->mm, vaddr, args->pudp, pud);
>>  flush_dcache_page(page);
>>  pudp_set_wrprotect(args->mm, vaddr, args->pudp);
>> @@ -374,6 +380,7 @@ static void __init pud_advanced_tests(struct 
>> pgtable_debug_args *args)
>>  WARN_ON(!pud_none(pud));
>>  #endif /* __PAGETABLE_PMD_FOLDED */
>>  pud = pfn_pud(args->pud_pfn, args->page_prot);
>> +pud = pud_mkdevmap(pud);
>>  pud = pud_wrprotect(pud);
>>  pud = pud_mkclean(pud);
>>  set_pud_at(args->mm, vaddr, args->pudp, pud);
>> @@ -391,6 +398,7 @@ static void __init pud_advanced_tests(struct 
>> pgtable_debug_args *args)
>>  #endif /* __PAGETABLE_PMD_FOLDED */
>>  
>>  pud = pfn_pud(args->pud_pfn, args->page_prot);
>> +pud = pud_mkdevmap(pud);
>>  pud = pud_mkyoung(pud);
>>  set_pud_at(args->mm, vaddr, args->pudp, pud);
>>  flush_dcache_page(page);


-aneesh

[PATCH] mm/debug_vm_pgtable: Fix BUG_ON with pud advanced test

2024-01-28 Thread Aneesh Kumar K.V (IBM) 
Architectures like powerpc add debug checks to ensure we find only devmap
PUD pte entries. These debug checks are only done with CONFIG_DEBUG_VM.
This patch marks the ptes used for PUD advanced test devmap pte entries
so that we don't hit on debug checks on architecture like ppc64 as
below.

WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 
radix__pud_hugepage_update+0x38/0x138

NIP [c00a7004] radix__pud_hugepage_update+0x38/0x138
LR [c00a77a8] radix__pudp_huge_get_and_clear+0x28/0x60
Call Trace:
[c4a2f950] [c4a2f9a0] 0xc4a2f9a0 (unreliable)
[c4a2f980] [000d34c1] 0xd34c1
[c4a2f9a0] [c206ba98] pud_advanced_tests+0x118/0x334
[c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
[c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388

Also

 kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202!
 

 NIP [c0096510] pudp_huge_get_and_clear_full+0x98/0x174
 LR [c206bb34] pud_advanced_tests+0x1b4/0x334
 Call Trace:
 [c4a2f950] [000d34c1] 0xd34c1 (unreliable)
 [c4a2f9a0] [c206bb34] pud_advanced_tests+0x1b4/0x334
 [c4a2fa40] [c206db34] debug_vm_pgtable+0xcbc/0x1c48
 [c4a2fc10] [c000fd28] do_one_initcall+0x60/0x388

Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage")
Signed-off-by: Aneesh Kumar K.V (IBM) 
---
 mm/debug_vm_pgtable.c | 8 
 1 file changed, 8 insertions(+)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 5662e29fe253..65c19025da3d 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -362,6 +362,12 @@ static void __init pud_advanced_tests(struct 
pgtable_debug_args *args)
vaddr &= HPAGE_PUD_MASK;
 
pud = pfn_pud(args->pud_pfn, args->page_prot);
+   /*
+* Some architectures have debug checks to make sure
+* huge pud mapping are only found with devmap entries
+* For now test with only devmap entries.
+*/
+   pud = pud_mkdevmap(pud);
set_pud_at(args->mm, vaddr, args->pudp, pud);
flush_dcache_page(page);
pudp_set_wrprotect(args->mm, vaddr, args->pudp);
@@ -374,6 +380,7 @@ static void __init pud_advanced_tests(struct 
pgtable_debug_args *args)
WARN_ON(!pud_none(pud));
 #endif /* __PAGETABLE_PMD_FOLDED */
pud = pfn_pud(args->pud_pfn, args->page_prot);
+   pud = pud_mkdevmap(pud);
pud = pud_wrprotect(pud);
pud = pud_mkclean(pud);
set_pud_at(args->mm, vaddr, args->pudp, pud);
@@ -391,6 +398,7 @@ static void __init pud_advanced_tests(struct 
pgtable_debug_args *args)
 #endif /* __PAGETABLE_PMD_FOLDED */
 
pud = pfn_pud(args->pud_pfn, args->page_prot);
+   pud = pud_mkdevmap(pud);
pud = pud_mkyoung(pud);
set_pud_at(args->mm, vaddr, args->pudp, pud);
flush_dcache_page(page);
-- 
2.43.0