diff mbox series

[3/8] mm/debug: Factor PagePoisoned out of __dump_page

Message ID 20210430145549.2662354-4-willy@infradead.org (mailing list archive)
State New
Headers show
Series Folio Prequel patches | expand

Commit Message

Matthew Wilcox April 30, 2021, 2:55 p.m. UTC
Move the PagePoisoned test into dump_page().  Skip the hex print
for poisoned pages -- we know they're full of ffffffff.  Move the
reason printing from __dump_page() to dump_page().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 mm/debug.c | 25 +++++++------------------
 1 file changed, 7 insertions(+), 18 deletions(-)

Comments

Kefeng Wang May 12, 2021, 3:29 a.m. UTC | #1
On 2021/4/30 22:55, Matthew Wilcox (Oracle) wrote:
> Move the PagePoisoned test into dump_page().  Skip the hex print
> for poisoned pages -- we know they're full of ffffffff.  Move the
> reason printing from __dump_page() to dump_page().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: William Kucharski <william.kucharski@oracle.com>
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
>   mm/debug.c | 25 +++++++------------------
>   1 file changed, 7 insertions(+), 18 deletions(-)
> 
> diff --git a/mm/debug.c b/mm/debug.c
> index 84cdcd0f7bd3..e73fe0a8ec3d 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -42,11 +42,10 @@ const struct trace_print_flags vmaflag_names[] = {
>   	{0, NULL}
>   };
>   
> -static void __dump_page(struct page *page, const char *reason)
> +static void __dump_page(struct page *page)
>   {
>   	struct page *head = compound_head(page);
>   	struct address_space *mapping;
> -	bool page_poisoned = PagePoisoned(page);
>   	bool compound = PageCompound(page);
>   	/*
>   	 * Accessing the pageblock without the zone lock. It could change to
> @@ -58,16 +57,6 @@ static void __dump_page(struct page *page, const char *reason)
>   	int mapcount;
>   	char *type = "";
>   
> -	/*
> -	 * If struct page is poisoned don't access Page*() functions as that
> -	 * leads to recursive loop. Page*() check for poisoned pages, and calls
> -	 * dump_page() when detected.
> -	 */
> -	if (page_poisoned) {
> -		pr_warn("page:%px is uninitialized and poisoned", page);
> -		goto hex_only;
> -	}
> -
>   	if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
>   		/*
>   		 * Corrupt page, so we cannot call page_mapping. Instead, do a
> @@ -173,8 +162,6 @@ static void __dump_page(struct page *page, const char *reason)
>   
>   	pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
>   		page_cma ? " CMA" : "");
> -
> -hex_only:
>   	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
>   			sizeof(unsigned long), page,
>   			sizeof(struct page), false);
> @@ -182,14 +169,16 @@ static void __dump_page(struct page *page, const char *reason)
>   		print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
>   			sizeof(unsigned long), head,
>   			sizeof(struct page), false);
> -
> -	if (reason)
> -		pr_warn("page dumped because: %s\n", reason);
>   }
>   
>   void dump_page(struct page *page, const char *reason)
>   {
> -	__dump_page(page, reason);
> +	if (PagePoisoned(page))
> +		pr_warn("page:%p is uninitialized and poisoned", page);
> +	else
> +		__dump_page(page);

Hi Matthew, dump_page_owenr() should be called when !PagePoisoned, right?


> +	if (reason)
> +		pr_warn("page dumped because: %s\n", reason);
>   	dump_page_owner(page);
>   }
>   EXPORT_SYMBOL(dump_page);
>
Matthew Wilcox May 12, 2021, 3:38 a.m. UTC | #2
On Wed, May 12, 2021 at 11:29:06AM +0800, Kefeng Wang wrote:
> >   void dump_page(struct page *page, const char *reason)
> >   {
> > -	__dump_page(page, reason);
> > +	if (PagePoisoned(page))
> > +		pr_warn("page:%p is uninitialized and poisoned", page);
> > +	else
> > +		__dump_page(page);
> 
> Hi Matthew, dump_page_owenr() should be called when !PagePoisoned, right?
> 
> 
> > +	if (reason)
> > +		pr_warn("page dumped because: %s\n", reason);
> >   	dump_page_owner(page);
> >   }
> >   EXPORT_SYMBOL(dump_page);

dump_page_owner() is called whether the page is Poisoned or not ...
both before and after this patch.  Is there a problem with that?
Kefeng Wang May 12, 2021, 3:53 a.m. UTC | #3
On 2021/5/12 11:38, Matthew Wilcox wrote:
> On Wed, May 12, 2021 at 11:29:06AM +0800, Kefeng Wang wrote:
>>>    void dump_page(struct page *page, const char *reason)
>>>    {
>>> -	__dump_page(page, reason);
>>> +	if (PagePoisoned(page))
>>> +		pr_warn("page:%p is uninitialized and poisoned", page);
>>> +	else
>>> +		__dump_page(page);
>>
>> Hi Matthew, dump_page_owenr() should be called when !PagePoisoned, right?
>>
>>
>>> +	if (reason)
>>> +		pr_warn("page dumped because: %s\n", reason);
>>>    	dump_page_owner(page);
>>>    }
>>>    EXPORT_SYMBOL(dump_page);
> 
> dump_page_owner() is called whether the page is Poisoned or not ...
> both before and after this patch.  Is there a problem with that?

struct page_ext *page_ext = lookup_page_ext(page);

   unsigned long pfn = page_to_pfn(page);
   struct mem_section *section = __pfn_to_section(pfn);
   if (!section->page_ext)

If page is Poisoned, I guess the section maybe NULL,
so section->page_ext may meet NULL pointer dereference,
is it possible?


> 
> .
>
diff mbox series

Patch

diff --git a/mm/debug.c b/mm/debug.c
index 84cdcd0f7bd3..e73fe0a8ec3d 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -42,11 +42,10 @@  const struct trace_print_flags vmaflag_names[] = {
 	{0, NULL}
 };
 
-static void __dump_page(struct page *page, const char *reason)
+static void __dump_page(struct page *page)
 {
 	struct page *head = compound_head(page);
 	struct address_space *mapping;
-	bool page_poisoned = PagePoisoned(page);
 	bool compound = PageCompound(page);
 	/*
 	 * Accessing the pageblock without the zone lock. It could change to
@@ -58,16 +57,6 @@  static void __dump_page(struct page *page, const char *reason)
 	int mapcount;
 	char *type = "";
 
-	/*
-	 * If struct page is poisoned don't access Page*() functions as that
-	 * leads to recursive loop. Page*() check for poisoned pages, and calls
-	 * dump_page() when detected.
-	 */
-	if (page_poisoned) {
-		pr_warn("page:%px is uninitialized and poisoned", page);
-		goto hex_only;
-	}
-
 	if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
 		/*
 		 * Corrupt page, so we cannot call page_mapping. Instead, do a
@@ -173,8 +162,6 @@  static void __dump_page(struct page *page, const char *reason)
 
 	pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
 		page_cma ? " CMA" : "");
-
-hex_only:
 	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 			sizeof(unsigned long), page,
 			sizeof(struct page), false);
@@ -182,14 +169,16 @@  static void __dump_page(struct page *page, const char *reason)
 		print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
 			sizeof(unsigned long), head,
 			sizeof(struct page), false);
-
-	if (reason)
-		pr_warn("page dumped because: %s\n", reason);
 }
 
 void dump_page(struct page *page, const char *reason)
 {
-	__dump_page(page, reason);
+	if (PagePoisoned(page))
+		pr_warn("page:%p is uninitialized and poisoned", page);
+	else
+		__dump_page(page);
+	if (reason)
+		pr_warn("page dumped because: %s\n", reason);
 	dump_page_owner(page);
 }
 EXPORT_SYMBOL(dump_page);