Re: [PATCH v2] powerpc/s64: Clarify that radix lacks DEBUG_PAGEALLOC

2021-11-02 Thread Michael Ellerman 
On Thu, 14 Oct 2021 08:04:38 +1030, Joel Stanley wrote:
> The page_alloc.c code will call into __kernel_map_pages when
> DEBUG_PAGEALLOC is configured and enabled.
> 
> As the implementation assumes hash, this should crash spectacularly if
> not for a bit of luck in __kernel_map_pages. In this function
> linear_map_hash_count is always zero, the for loop exits without doing
> any damage.
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/s64: Clarify that radix lacks DEBUG_PAGEALLOC
  https://git.kernel.org/powerpc/c/4f703e7faa67a116016c4678fc88b507c12670c9

cheers

Re: [PATCH v2] powerpc/s64: Clarify that radix lacks DEBUG_PAGEALLOC

2021-10-15 Thread Michael Ellerman 
Christophe Leroy  writes:
> Le 13/10/2021 à 23:34, Joel Stanley a écrit :
>> The page_alloc.c code will call into __kernel_map_pages when
>> DEBUG_PAGEALLOC is configured and enabled.
>> 
>> As the implementation assumes hash, this should crash spectacularly if
>> not for a bit of luck in __kernel_map_pages. In this function
>> linear_map_hash_count is always zero, the for loop exits without doing
>> any damage.
>> 
>> There are no other platforms that determine if they support
>> debug_pagealloc at runtime. Instead of adding code to mm/page_alloc.c to
>> do that, this change turns the map/unmap into a noop when in radix
>> mode and prints a warning once.
>> 
>> Signed-off-by: Joel Stanley 
>> ---
>> v2: Put __kernel_map_pages in pgtable.h
>> 
>>   arch/powerpc/include/asm/book3s/64/hash.h|  2 ++
>>   arch/powerpc/include/asm/book3s/64/pgtable.h | 11 +++
>>   arch/powerpc/include/asm/book3s/64/radix.h   |  3 +++
>>   arch/powerpc/mm/book3s64/hash_utils.c|  2 +-
>>   arch/powerpc/mm/book3s64/radix_pgtable.c |  7 +++
>>   5 files changed, 24 insertions(+), 1 deletion(-)
>> 
>> diff --git a/arch/powerpc/include/asm/book3s/64/hash.h 
>> b/arch/powerpc/include/asm/book3s/64/hash.h
>> index d959b0195ad9..674fe0e890dc 100644
>> --- a/arch/powerpc/include/asm/book3s/64/hash.h
>> +++ b/arch/powerpc/include/asm/book3s/64/hash.h
>> @@ -255,6 +255,8 @@ int hash__create_section_mapping(unsigned long start, 
>> unsigned long end,
>>   int nid, pgprot_t prot);
>>   int hash__remove_section_mapping(unsigned long start, unsigned long end);
>>   
>> +void hash__kernel_map_pages(struct page *page, int numpages, int enable);
>> +
>>   #endif /* !__ASSEMBLY__ */
>>   #endif /* __KERNEL__ */
>>   #endif /* _ASM_POWERPC_BOOK3S_64_HASH_H */
>> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h 
>> b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> index 5d34a8646f08..265661ded238 100644
>> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
>> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> @@ -1101,6 +1101,17 @@ static inline void vmemmap_remove_mapping(unsigned 
>> long start,
>>   }
>>   #endif
>>   
>> +#ifdef CONFIG_DEBUG_PAGEALLOC
>> +static inline void __kernel_map_pages(struct page *page, int numpages, int 
>> enable)
>> +{
>> +if (radix_enabled()) {
>> +radix__kernel_map_pages(page, numpages, enable);
>> +return;
>> +}
>> +hash__kernel_map_pages(page, numpages, enable);
>
> I'd have prefered something like below
>
>   if (radix_enabled())
>   radix__kernel_map_pages(page, numpages, enable);
>   else
>   hash__kernel_map_pages(page, numpages, enable);

I did that when applying.

cheers

Re: [PATCH v2] powerpc/s64: Clarify that radix lacks DEBUG_PAGEALLOC

2021-10-14 Thread Christophe Leroy 




Le 13/10/2021 à 23:34, Joel Stanley a écrit :

The page_alloc.c code will call into __kernel_map_pages when
DEBUG_PAGEALLOC is configured and enabled.

As the implementation assumes hash, this should crash spectacularly if
not for a bit of luck in __kernel_map_pages. In this function
linear_map_hash_count is always zero, the for loop exits without doing
any damage.

There are no other platforms that determine if they support
debug_pagealloc at runtime. Instead of adding code to mm/page_alloc.c to
do that, this change turns the map/unmap into a noop when in radix
mode and prints a warning once.

Signed-off-by: Joel Stanley 
---
v2: Put __kernel_map_pages in pgtable.h

  arch/powerpc/include/asm/book3s/64/hash.h|  2 ++
  arch/powerpc/include/asm/book3s/64/pgtable.h | 11 +++
  arch/powerpc/include/asm/book3s/64/radix.h   |  3 +++
  arch/powerpc/mm/book3s64/hash_utils.c|  2 +-
  arch/powerpc/mm/book3s64/radix_pgtable.c |  7 +++
  5 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/book3s/64/hash.h 
b/arch/powerpc/include/asm/book3s/64/hash.h
index d959b0195ad9..674fe0e890dc 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -255,6 +255,8 @@ int hash__create_section_mapping(unsigned long start, 
unsigned long end,
 int nid, pgprot_t prot);
  int hash__remove_section_mapping(unsigned long start, unsigned long end);
  
+void hash__kernel_map_pages(struct page *page, int numpages, int enable);

+
  #endif /* !__ASSEMBLY__ */
  #endif /* __KERNEL__ */
  #endif /* _ASM_POWERPC_BOOK3S_64_HASH_H */
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h 
b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 5d34a8646f08..265661ded238 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -1101,6 +1101,17 @@ static inline void vmemmap_remove_mapping(unsigned long 
start,
  }
  #endif
  
+#ifdef CONFIG_DEBUG_PAGEALLOC

+static inline void __kernel_map_pages(struct page *page, int numpages, int 
enable)
+{
+   if (radix_enabled()) {
+   radix__kernel_map_pages(page, numpages, enable);
+   return;
+   }
+   hash__kernel_map_pages(page, numpages, enable);


I'd have prefered something like below

if (radix_enabled())
radix__kernel_map_pages(page, numpages, enable);
else
hash__kernel_map_pages(page, numpages, enable);


But regardless,

Reviewed-by: Christophe Leroy 




+}
+#endif
+
  static inline pte_t pmd_pte(pmd_t pmd)
  {
return __pte_raw(pmd_raw(pmd));
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h 
b/arch/powerpc/include/asm/book3s/64/radix.h
index 59cab558e2f0..d090d9612348 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -316,5 +316,8 @@ int radix__create_section_mapping(unsigned long start, 
unsigned long end,
  int nid, pgprot_t prot);
  int radix__remove_section_mapping(unsigned long start, unsigned long end);
  #endif /* CONFIG_MEMORY_HOTPLUG */
+
+void radix__kernel_map_pages(struct page *page, int numpages, int enable);
+
  #endif /* __ASSEMBLY__ */
  #endif
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c 
b/arch/powerpc/mm/book3s64/hash_utils.c
index c145776d3ae5..cfd45245d009 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1988,7 +1988,7 @@ static void kernel_unmap_linear_page(unsigned long vaddr, 
unsigned long lmi)
 mmu_kernel_ssize, 0);
  }
  
-void __kernel_map_pages(struct page *page, int numpages, int enable)

+void hash__kernel_map_pages(struct page *page, int numpages, int enable)
  {
unsigned long flags, vaddr, lmi;
int i;
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c 
b/arch/powerpc/mm/book3s64/radix_pgtable.c
index ae20add7954a..83b33418ad28 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -920,6 +920,13 @@ void __meminit radix__vmemmap_remove_mapping(unsigned long 
start, unsigned long
  #endif
  #endif
  
+#ifdef CONFIG_DEBUG_PAGEALLOC

+void radix__kernel_map_pages(struct page *page, int numpages, int enable)
+{
+pr_warn_once("DEBUG_PAGEALLOC not supported in radix mode\n");
+}
+#endif
+
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  
  unsigned long radix__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr,

[PATCH v2] powerpc/s64: Clarify that radix lacks DEBUG_PAGEALLOC

2021-10-13 Thread Joel Stanley 
The page_alloc.c code will call into __kernel_map_pages when
DEBUG_PAGEALLOC is configured and enabled.

As the implementation assumes hash, this should crash spectacularly if
not for a bit of luck in __kernel_map_pages. In this function
linear_map_hash_count is always zero, the for loop exits without doing
any damage.

There are no other platforms that determine if they support
debug_pagealloc at runtime. Instead of adding code to mm/page_alloc.c to
do that, this change turns the map/unmap into a noop when in radix
mode and prints a warning once.

Signed-off-by: Joel Stanley 
---
v2: Put __kernel_map_pages in pgtable.h

 arch/powerpc/include/asm/book3s/64/hash.h|  2 ++
 arch/powerpc/include/asm/book3s/64/pgtable.h | 11 +++
 arch/powerpc/include/asm/book3s/64/radix.h   |  3 +++
 arch/powerpc/mm/book3s64/hash_utils.c|  2 +-
 arch/powerpc/mm/book3s64/radix_pgtable.c |  7 +++
 5 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/book3s/64/hash.h 
b/arch/powerpc/include/asm/book3s/64/hash.h
index d959b0195ad9..674fe0e890dc 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -255,6 +255,8 @@ int hash__create_section_mapping(unsigned long start, 
unsigned long end,
 int nid, pgprot_t prot);
 int hash__remove_section_mapping(unsigned long start, unsigned long end);
 
+void hash__kernel_map_pages(struct page *page, int numpages, int enable);
+
 #endif /* !__ASSEMBLY__ */
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_BOOK3S_64_HASH_H */
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h 
b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 5d34a8646f08..265661ded238 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -1101,6 +1101,17 @@ static inline void vmemmap_remove_mapping(unsigned long 
start,
 }
 #endif
 
+#ifdef CONFIG_DEBUG_PAGEALLOC
+static inline void __kernel_map_pages(struct page *page, int numpages, int 
enable)
+{
+   if (radix_enabled()) {
+   radix__kernel_map_pages(page, numpages, enable);
+   return;
+   }
+   hash__kernel_map_pages(page, numpages, enable);
+}
+#endif
+
 static inline pte_t pmd_pte(pmd_t pmd)
 {
return __pte_raw(pmd_raw(pmd));
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h 
b/arch/powerpc/include/asm/book3s/64/radix.h
index 59cab558e2f0..d090d9612348 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -316,5 +316,8 @@ int radix__create_section_mapping(unsigned long start, 
unsigned long end,
  int nid, pgprot_t prot);
 int radix__remove_section_mapping(unsigned long start, unsigned long end);
 #endif /* CONFIG_MEMORY_HOTPLUG */
+
+void radix__kernel_map_pages(struct page *page, int numpages, int enable);
+
 #endif /* __ASSEMBLY__ */
 #endif
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c 
b/arch/powerpc/mm/book3s64/hash_utils.c
index c145776d3ae5..cfd45245d009 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1988,7 +1988,7 @@ static void kernel_unmap_linear_page(unsigned long vaddr, 
unsigned long lmi)
 mmu_kernel_ssize, 0);
 }
 
-void __kernel_map_pages(struct page *page, int numpages, int enable)
+void hash__kernel_map_pages(struct page *page, int numpages, int enable)
 {
unsigned long flags, vaddr, lmi;
int i;
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c 
b/arch/powerpc/mm/book3s64/radix_pgtable.c
index ae20add7954a..83b33418ad28 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -920,6 +920,13 @@ void __meminit radix__vmemmap_remove_mapping(unsigned long 
start, unsigned long
 #endif
 #endif
 
+#ifdef CONFIG_DEBUG_PAGEALLOC
+void radix__kernel_map_pages(struct page *page, int numpages, int enable)
+{
+pr_warn_once("DEBUG_PAGEALLOC not supported in radix mode\n");
+}
+#endif
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 
 unsigned long radix__pmd_hugepage_update(struct mm_struct *mm, unsigned long 
addr,
-- 
2.33.0