linux-kernel - Re: [patch 3/3] mm: move page->mem_cgroup bad page handling into generic code

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Date:	Mon, 3 Nov 2014 17:58:33 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Vladimir Davydov <vdavydov@...allels.com>,
	Tejun Heo <tj@...nel.org>, David Miller <davem@...emloft.net>,
	linux-mm@...ck.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 3/3] mm: move page->mem_cgroup bad page handling into
 generic code

On Sat 01-11-14 23:15:56, Johannes Weiner wrote:
> Now that the external page_cgroup data structure and its lookup is
> gone, let the generic bad_page() check for page->mem_cgroup sanity.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>

Acked-by: Michal Hocko <mhocko@...e.cz>

> ---
>  include/linux/memcontrol.h |  4 ----
>  mm/debug.c                 |  5 ++++-
>  mm/memcontrol.c            | 15 ---------------
>  mm/page_alloc.c            | 12 ++++++++----
>  4 files changed, 12 insertions(+), 24 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index dafba59b31b4..e789551d4db0 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -173,10 +173,6 @@ static inline void mem_cgroup_count_vm_event(struct mm_struct *mm,
>  void mem_cgroup_split_huge_fixup(struct page *head);
>  #endif
>  
> -#ifdef CONFIG_DEBUG_VM
> -bool mem_cgroup_bad_page_check(struct page *page);
> -void mem_cgroup_print_bad_page(struct page *page);
> -#endif
>  #else /* CONFIG_MEMCG */
>  struct mem_cgroup;
>  
> diff --git a/mm/debug.c b/mm/debug.c
> index 5ce45c9a29b5..0e58f3211f89 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -95,7 +95,10 @@ void dump_page_badflags(struct page *page, const char *reason,
>  		dump_flags(page->flags & badflags,
>  				pageflag_names, ARRAY_SIZE(pageflag_names));
>  	}
> -	mem_cgroup_print_bad_page(page);
> +#ifdef CONFIG_MEMCG
> +	if (page->mem_cgroup)
> +		pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup);
> +#endif
>  }
>  
>  void dump_page(struct page *page, const char *reason)
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index fbb41a170eae..3645641513a1 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3157,21 +3157,6 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
>  }
>  #endif
>  
> -#ifdef CONFIG_DEBUG_VM
> -bool mem_cgroup_bad_page_check(struct page *page)
> -{
> -	if (mem_cgroup_disabled())
> -		return false;
> -
> -	return page->mem_cgroup != NULL;
> -}
> -
> -void mem_cgroup_print_bad_page(struct page *page)
> -{
> -	pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup);
> -}
> -#endif
> -
>  static DEFINE_MUTEX(memcg_limit_mutex);
>  
>  static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 6a952237a677..161da09fcda2 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -653,8 +653,10 @@ static inline int free_pages_check(struct page *page)
>  		bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
>  		bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
>  	}
> -	if (unlikely(mem_cgroup_bad_page_check(page)))
> -		bad_reason = "cgroup check failed";
> +#ifdef CONFIG_MEMCG
> +	if (unlikely(page->mem_cgroup))
> +		bad_reason = "page still charged to cgroup";
> +#endif
>  	if (unlikely(bad_reason)) {
>  		bad_page(page, bad_reason, bad_flags);
>  		return 1;
> @@ -920,8 +922,10 @@ static inline int check_new_page(struct page *page)
>  		bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
>  		bad_flags = PAGE_FLAGS_CHECK_AT_PREP;
>  	}
> -	if (unlikely(mem_cgroup_bad_page_check(page)))
> -		bad_reason = "cgroup check failed";
> +#ifdef CONFIG_MEMCG
> +	if (unlikely(page->mem_cgroup))
> +		bad_reason = "page still charged to cgroup";
> +#endif
>  	if (unlikely(bad_reason)) {
>  		bad_page(page, bad_reason, bad_flags);
>  		return 1;
> -- 
> 2.1.3
> 

-- 
Michal Hocko
SUSE Labs
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