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

From: Michal Hocko
Date: Mon Nov 03 2014 - 11:58:47 EST


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@xxxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxx>

> ---
> 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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