[PATCH 1/3] mm/page_alloc: Use dump_page() directly

[PATCH 1/3] mm/page_alloc: Use dump_page() directly

[Kefeng Wang]

Simplfy use dump_page().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/page_alloc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a2fe714aed93..f23702e7c564 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -658,8 +658,7 @@ static void bad_page(struct page *page, const char *reason)
 
 	pr_alert("BUG: Bad page state in process %s  pfn:%05lx\n",
 		current->comm, page_to_pfn(page));
-	__dump_page(page, reason);
-	dump_page_owner(page);
+	dump_page(page, reason);
 
 	print_modules();
 	dump_stack();
-- 
2.26.2

[PATCH 2/3] mm: Make __dump_page() static

[Kefeng Wang]

No __dump_page() caller, so make it static.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/linux/mmdebug.h | 1 -
 mm/debug.c              | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 5d0767cb424a..9086157b46f3 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -10,7 +10,6 @@ struct vm_area_struct;
 struct mm_struct;
 
 extern void dump_page(struct page *page, const char *reason);
-extern void __dump_page(struct page *page, const char *reason);
 void dump_vma(const struct vm_area_struct *vma);
 void dump_mm(const struct mm_struct *mm);
 
diff --git a/mm/debug.c b/mm/debug.c
index 0bdda8407f71..84cdcd0f7bd3 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -42,7 +42,7 @@ const struct trace_print_flags vmaflag_names[] = {
 	{0, NULL}
 };
 
-void __dump_page(struct page *page, const char *reason)
+static void __dump_page(struct page *page, const char *reason)
 {
 	struct page *head = compound_head(page);
 	struct address_space *mapping;
-- 
2.26.2

[PATCH 3/3] mm/debug: Check page poisoned firstly in dump_page()

[Kefeng Wang]

If page is poisoned, it will crash when we call some page related
functions, so must check whether the page is poisoned or not firstly.

Fixes: 6197ab984b41 ("mm: improve dump_page() for compound pages")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/debug.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/mm/debug.c b/mm/debug.c
index 84cdcd0f7bd3..cf84cd9df527 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -44,20 +44,19 @@ const struct trace_print_flags vmaflag_names[] = {
 
 static void __dump_page(struct page *page, const char *reason)
 {
-	struct page *head = compound_head(page);
+	struct page *head = NULL;
 	struct address_space *mapping;
-	bool page_poisoned = PagePoisoned(page);
-	bool compound = PageCompound(page);
+	bool compound;
 	/*
 	 * Accessing the pageblock without the zone lock. It could change to
 	 * "isolate" again in the meantime, but since we are just dumping the
 	 * state for debugging, it should be fine to accept a bit of
 	 * inaccuracy here due to racing.
 	 */
-	bool page_cma = is_migrate_cma_page(page);
+	bool page_cma;
 	int mapcount;
 	char *type = "";
-
+	bool page_poisoned = PagePoisoned(page);
 	/*
 	 * If struct page is poisoned don't access Page*() functions as that
 	 * leads to recursive loop. Page*() check for poisoned pages, and calls
@@ -68,6 +67,10 @@ static void __dump_page(struct page *page, const char *reason)
 		goto hex_only;
 	}
 
+	head = compound_head(page);
+	page_poisoned = PagePoisoned(page);
+	page_cma = is_migrate_cma_page(page);
+
 	if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
 		/*
 		 * Corrupt page, so we cannot call page_mapping. Instead, do a
@@ -178,7 +181,7 @@ static void __dump_page(struct page *page, const char *reason)
 	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 			sizeof(unsigned long), page,
 			sizeof(struct page), false);
-	if (head != page)
+	if (head && head != page)
 		print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
 			sizeof(unsigned long), head,
 			sizeof(struct page), false);
-- 
2.26.2

Re: [PATCH 3/3] mm/debug: Check page poisoned firstly in dump_page()

[Matthew Wilcox]

On Wed, May 12, 2021 at 11:10:57AM +0800, Kefeng Wang wrote:
> If page is poisoned, it will crash when we call some page related
> functions, so must check whether the page is poisoned or not firstly.

https://lore.kernel.org/linux-mm/20210430145549.2662354-4-willy@infradead.org/

> Fixes: 6197ab984b41 ("mm: improve dump_page() for compound pages")
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/debug.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/debug.c b/mm/debug.c
> index 84cdcd0f7bd3..cf84cd9df527 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -44,20 +44,19 @@ const struct trace_print_flags vmaflag_names[] = {
>  
>  static void __dump_page(struct page *page, const char *reason)
>  {
> -	struct page *head = compound_head(page);
> +	struct page *head = NULL;
>  	struct address_space *mapping;
> -	bool page_poisoned = PagePoisoned(page);
> -	bool compound = PageCompound(page);
> +	bool compound;
>  	/*
>  	 * Accessing the pageblock without the zone lock. It could change to
>  	 * "isolate" again in the meantime, but since we are just dumping the
>  	 * state for debugging, it should be fine to accept a bit of
>  	 * inaccuracy here due to racing.
>  	 */
> -	bool page_cma = is_migrate_cma_page(page);
> +	bool page_cma;
>  	int mapcount;
>  	char *type = "";
> -
> +	bool page_poisoned = PagePoisoned(page);
>  	/*
>  	 * If struct page is poisoned don't access Page*() functions as that
>  	 * leads to recursive loop. Page*() check for poisoned pages, and calls
> @@ -68,6 +67,10 @@ static void __dump_page(struct page *page, const char *reason)
>  		goto hex_only;
>  	}
>  
> +	head = compound_head(page);
> +	page_poisoned = PagePoisoned(page);
> +	page_cma = is_migrate_cma_page(page);
> +
>  	if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
>  		/*
>  		 * Corrupt page, so we cannot call page_mapping. Instead, do a
> @@ -178,7 +181,7 @@ static void __dump_page(struct page *page, const char *reason)
>  	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
>  			sizeof(unsigned long), page,
>  			sizeof(struct page), false);
> -	if (head != page)
> +	if (head && head != page)
>  		print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
>  			sizeof(unsigned long), head,
>  			sizeof(struct page), false);
> -- 
> 2.26.2
> 
> 

Re: [PATCH 3/3] mm/debug: Check page poisoned firstly in dump_page()

[Kefeng Wang]

On 2021/5/12 11:15, Matthew Wilcox wrote:
> On Wed, May 12, 2021 at 11:10:57AM +0800, Kefeng Wang wrote:
>> If page is poisoned, it will crash when we call some page related
>> functions, so must check whether the page is poisoned or not firstly.
> 
> https://lore.kernel.org/linux-mm/20210430145549.2662354-4-willy@infradead.org/

OK, please ignore them, I found this when debug arm issue in lts5.10, 
thanks.

> 
>> Fixes: 6197ab984b41 ("mm: improve dump_page() for compound pages")
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>> ---
>>   mm/debug.c | 15 +++++++++------
>>   1 file changed, 9 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/debug.c b/mm/debug.c
>> index 84cdcd0f7bd3..cf84cd9df527 100644
>> --- a/mm/debug.c
>> +++ b/mm/debug.c
>> @@ -44,20 +44,19 @@ const struct trace_print_flags vmaflag_names[] = {
>>   
>>   static void __dump_page(struct page *page, const char *reason)
>>   {
>> -	struct page *head = compound_head(page);
>> +	struct page *head = NULL;
>>   	struct address_space *mapping;
>> -	bool page_poisoned = PagePoisoned(page);
>> -	bool compound = PageCompound(page);
>> +	bool compound;
>>   	/*
>>   	 * Accessing the pageblock without the zone lock. It could change to
>>   	 * "isolate" again in the meantime, but since we are just dumping the
>>   	 * state for debugging, it should be fine to accept a bit of
>>   	 * inaccuracy here due to racing.
>>   	 */
>> -	bool page_cma = is_migrate_cma_page(page);
>> +	bool page_cma;
>>   	int mapcount;
>>   	char *type = "";
>> -
>> +	bool page_poisoned = PagePoisoned(page);
>>   	/*
>>   	 * If struct page is poisoned don't access Page*() functions as that
>>   	 * leads to recursive loop. Page*() check for poisoned pages, and calls
>> @@ -68,6 +67,10 @@ static void __dump_page(struct page *page, const char *reason)
>>   		goto hex_only;
>>   	}
>>   
>> +	head = compound_head(page);
>> +	page_poisoned = PagePoisoned(page);
>> +	page_cma = is_migrate_cma_page(page);
>> +
>>   	if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
>>   		/*
>>   		 * Corrupt page, so we cannot call page_mapping. Instead, do a
>> @@ -178,7 +181,7 @@ static void __dump_page(struct page *page, const char *reason)
>>   	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
>>   			sizeof(unsigned long), page,
>>   			sizeof(struct page), false);
>> -	if (head != page)
>> +	if (head && head != page)
>>   		print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
>>   			sizeof(unsigned long), head,
>>   			sizeof(struct page), false);
>> -- 
>> 2.26.2
>>
>>
> .
> 

Re: [PATCH 1/3] mm/page_alloc: Use dump_page() directly

[Matthew Wilcox]

On Wed, May 12, 2021 at 11:10:55AM +0800, Kefeng Wang wrote:
> Simplfy use dump_page().

https://lore.kernel.org/linux-mm/20210430145549.2662354-3-willy@infradead.org/

> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/page_alloc.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index a2fe714aed93..f23702e7c564 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -658,8 +658,7 @@ static void bad_page(struct page *page, const char *reason)
>  
>  	pr_alert("BUG: Bad page state in process %s  pfn:%05lx\n",
>  		current->comm, page_to_pfn(page));
> -	__dump_page(page, reason);
> -	dump_page_owner(page);
> +	dump_page(page, reason);
>  
>  	print_modules();
>  	dump_stack();
> -- 
> 2.26.2
>