Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 20 Jan 2020 20:33:43 +0800
From:   Wei Yang <richardw.yang@linux.intel.com>
To:     Anshuman Khandual <anshuman.khandual@arm.com>
Cc:     Wei Yang <richardw.yang@linux.intel.com>,
        akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, rientjes@google.com
Subject: Re: [Patch v2 3/4] mm/page_alloc.c: pass all bad reasons to
 bad_page()
Message-ID: <20200120123343.GD18028@richard>
Reply-To: Wei Yang <richardw.yang@linux.intel.com>
References: <20200120030415.15925-1-richardw.yang@linux.intel.com>
 <20200120030415.15925-4-richardw.yang@linux.intel.com>
 <d234b84b-b735-09f2-d7f1-e048fb9a3f87@arm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <d234b84b-b735-09f2-d7f1-e048fb9a3f87@arm.com>
User-Agent: Mutt/1.9.4 (2018-02-28)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Jan 20, 2020 at 12:03:20PM +0530, Anshuman Khandual wrote:
>
>
>On 01/20/2020 08:34 AM, Wei Yang wrote:
>> Now we can pass all bad reasons to __dump_page().
>> 
>> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>> ---
>>  mm/page_alloc.c | 52 ++++++++++++++++++++++++++-----------------------
>>  1 file changed, 28 insertions(+), 24 deletions(-)
>> 
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index a43b9d2482f2..a7b793c739fc 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -609,7 +609,7 @@ static inline int __maybe_unused bad_range(struct zone *zone, struct page *page)
>>  }
>>  #endif
>>  
>> -static void bad_page(struct page *page, const char *reason,
>> +static void bad_page(struct page *page, int nr, const char **reason,
>>  		unsigned long bad_flags)
>>  {
>>  	static unsigned long resume;
>> @@ -638,7 +638,7 @@ 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, 1, &reason);
>> +	__dump_page(page, nr, reason);
>>  	bad_flags &= page->flags;
>>  	if (bad_flags)
>>  		pr_alert("bad because of flags: %#lx(%pGp)\n",
>> @@ -1027,27 +1027,25 @@ static inline bool page_expected_state(struct page *page,
>>  
>>  static void free_pages_check_bad(struct page *page)
>>  {
>> -	const char *bad_reason;
>> -	unsigned long bad_flags;
>> -
>> -	bad_reason = NULL;
>> -	bad_flags = 0;
>> +	const char *bad_reason[5];
>
>s/5/NR_BAD_PAGE_REASONS
>
>
>> +	unsigned long bad_flags = 0;
>> +	int nr = 0;
>>  
>>  	if (unlikely(atomic_read(&page->_mapcount) != -1))
>> -		bad_reason = "nonzero mapcount";
>> +		bad_reason[nr++] = "nonzero mapcount";
>>  	if (unlikely(page->mapping != NULL))
>> -		bad_reason = "non-NULL mapping";
>> +		bad_reason[nr++] = "non-NULL mapping";
>>  	if (unlikely(page_ref_count(page) != 0))
>> -		bad_reason = "nonzero _refcount";
>> +		bad_reason[nr++] = "nonzero _refcount";
>>  	if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) {
>> -		bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
>> +		bad_reason[nr++] = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
>>  		bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
>>  	}
>>  #ifdef CONFIG_MEMCG
>>  	if (unlikely(page->mem_cgroup))
>> -		bad_reason = "page still charged to cgroup";
>> +		bad_reason[nr++] = "page still charged to cgroup";
>>  #endif
>> -	bad_page(page, bad_reason, bad_flags);
>> +	bad_page(page, nr, bad_reason, bad_flags);
>>  }
>>  
>>  static inline int free_pages_check(struct page *page)
>> @@ -1062,6 +1060,7 @@ static inline int free_pages_check(struct page *page)
>>  
>>  static int free_tail_pages_check(struct page *head_page, struct page *page)
>>  {
>> +	const char *reason;
>>  	int ret = 1;
>>  
>>  	/*
>> @@ -1078,7 +1077,8 @@ static int free_tail_pages_check(struct page *head_page, struct page *page)
>>  	case 1:
>>  		/* the first tail page: ->mapping may be compound_mapcount() */
>>  		if (unlikely(compound_mapcount(page))) {
>> -			bad_page(page, "nonzero compound_mapcount", 0);
>> +			reason = "nonzero compound_mapcount";
>> +			bad_page(page, 1, &reason, 0);
>>  			goto out;
>>  		}
>>  		break;
>> @@ -1090,17 +1090,20 @@ static int free_tail_pages_check(struct page *head_page, struct page *page)
>>  		break;
>>  	default:
>>  		if (page->mapping != TAIL_MAPPING) {
>> -			bad_page(page, "corrupted mapping in tail page", 0);
>> +			reason = "corrupted mapping in tail page";
>> +			bad_page(page, 1, &reason, 0);
>>  			goto out;
>>  		}
>>  		break;
>>  	}
>>  	if (unlikely(!PageTail(page))) {
>> -		bad_page(page, "PageTail not set", 0);
>> +		reason = "PageTail not set";
>> +		bad_page(page, 1, &reason, 0);
>>  		goto out;
>>  	}
>>  	if (unlikely(compound_head(page) != head_page)) {
>> -		bad_page(page, "compound_head not consistent", 0);
>> +		reason = "compound_head not consistent";
>> +		bad_page(page, 1, &reason, 0);
>>  		goto out;
>>  	}
>>  	ret = 0;
>> @@ -2041,29 +2044,30 @@ static inline void expand(struct zone *zone, struct page *page,
>>  
>>  static void check_new_page_bad(struct page *page)
>>  {
>> -	const char *bad_reason = NULL;
>> +	const char *bad_reason[5];
>
>s/5/NR_BAD_PAGE_REASONS 
>
>>  	unsigned long bad_flags = 0;
>> +	int nr = 0;
>>  
>>  	if (unlikely(atomic_read(&page->_mapcount) != -1))
>> -		bad_reason = "nonzero mapcount";
>> +		bad_reason[nr++] = "nonzero mapcount";
>>  	if (unlikely(page->mapping != NULL))
>> -		bad_reason = "non-NULL mapping";
>> +		bad_reason[nr++] = "non-NULL mapping";
>>  	if (unlikely(page_ref_count(page) != 0))
>> -		bad_reason = "nonzero _refcount";
>> +		bad_reason[nr++] = "nonzero _refcount";
>>  	if (unlikely(page->flags & __PG_HWPOISON)) {
>>  		/* Don't complain about hwpoisoned pages */
>>  		page_mapcount_reset(page); /* remove PageBuddy */
>>  		return;
>>  	}
>>  	if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_PREP)) {
>> -		bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
>> +		bad_reason[nr++] = "PAGE_FLAGS_CHECK_AT_PREP flag set";
>>  		bad_flags = PAGE_FLAGS_CHECK_AT_PREP;
>>  	}
>>  #ifdef CONFIG_MEMCG
>>  	if (unlikely(page->mem_cgroup))
>> -		bad_reason = "page still charged to cgroup";
>> +		bad_reason[nr++] = "page still charged to cgroup";
>>  #endif
>> -	bad_page(page, bad_reason, bad_flags);
>> +	bad_page(page, 1, bad_reason, bad_flags);
>This should be 'nr' here instead ?
>

Thanks, I missed this one.

>>  }
>>  
>>  /*
>> 

-- 
Wei Yang
Help you, Help me