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Date: Mon, 20 Jan 2020 20:33:43 +0800
From: Wei Yang <richardw.yang@...ux.intel.com>
To: Anshuman Khandual <anshuman.khandual@....com>
Cc: Wei Yang <richardw.yang@...ux.intel.com>,
akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, rientjes@...gle.com
Subject: Re: [Patch v2 3/4] mm/page_alloc.c: pass all bad reasons to
bad_page()
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@...ux.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
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