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Date: Mon, 20 Jan 2020 12:03:20 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Wei Yang <richardw.yang@...ux.intel.com>, akpm@...ux-foundation.org
Cc: 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 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 ?
> }
>
> /*
>
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