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From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Vlastimil Babka <vbabka@suse.cz>, Walter Wu <walter-zh.wu@mediatek.com>
Cc: Qian Cai <cai@lca.pw>, Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
	linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com
Subject: Re: [PATCH v3] mm/kasan: dump alloc and free stack for page allocator
Date: Mon, 16 Sep 2019 18:57:23 +0300
Message-ID: <4e76e7ce-1d61-524a-622b-663c01d19707@virtuozzo.com> (raw)
In-Reply-To: <6d58ce86-b2a4-40af-bf40-c604b457d086@suse.cz>

On 9/16/19 12:42 PM, Vlastimil Babka wrote:
> On 9/12/19 7:05 PM, Andrey Ryabinin wrote:
>>
>> Or another alternative option (and actually easier one to implement), leave PAGE_OWNER as is (no "select"s in Kconfigs)
>> Make PAGE_OWNER_FREE_STACK like this:
>>
>> +config PAGE_OWNER_FREE_STACK
>> +	def_bool KASAN || DEBUG_PAGEALLOC
>> +	depends on PAGE_OWNER
>> +
>>
>> So, users that want alloc/free stack will have to enable CONFIG_PAGE_OWNER=y and add page_owner=on to boot cmdline.
>>
>>
>> Basically the difference between these alternative is whether we enable page_owner by default or not. But there is always a possibility to disable it.
> 
> OK, how about this?
> 
 ...

> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c5d62f1c2851..d9e44671af3f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -710,8 +710,12 @@ static int __init early_debug_pagealloc(char *buf)
>  	if (kstrtobool(buf, &enable))
>  		return -EINVAL;
>  
> -	if (enable)
> +	if (enable) {
>  		static_branch_enable(&_debug_pagealloc_enabled);
> +#ifdef CONFIG_PAGE_OWNER
> +		page_owner_free_stack_disabled = false;

I think this won't work with CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT=y

> +#endif
> +	}
>  
>  	return 0;
>  }
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index dee931184788..b589bfbc4795 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -24,13 +24,15 @@ struct page_owner {
>  	short last_migrate_reason;
>  	gfp_t gfp_mask;
>  	depot_stack_handle_t handle;
> -#ifdef CONFIG_DEBUG_PAGEALLOC
> +#ifdef CONFIG_PAGE_OWNER_FREE_STACK
>  	depot_stack_handle_t free_handle;
>  #endif
>  };
>  
>  static bool page_owner_disabled = true;
> +bool page_owner_free_stack_disabled = true;
>  DEFINE_STATIC_KEY_FALSE(page_owner_inited);
> +static DEFINE_STATIC_KEY_FALSE(page_owner_free_stack);
>  
>  static depot_stack_handle_t dummy_handle;
>  static depot_stack_handle_t failure_handle;
> @@ -46,6 +48,9 @@ static int __init early_page_owner_param(char *buf)
>  	if (strcmp(buf, "on") == 0)
>  		page_owner_disabled = false;
>  
> +	if (!page_owner_disabled && IS_ENABLED(CONFIG_KASAN))

I'd rather keep all logic in one place, i.e. "if (!page_owner_disabled && (IS_ENABLED(CONFIG_KASAN) || debug_pagealloc_enabled())"
With this no changes in early_debug_pagealloc() required and CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT=y should also work correctly.

> +		page_owner_free_stack_disabled = false;
> +
>  	return 0;
>  }
>  early_param("page_owner", early_page_owner_param);
 


  reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-11  8:39 Walter Wu
2019-09-11 15:19 ` Qian Cai
2019-09-12 13:53   ` Vlastimil Babka
2019-09-12 14:08     ` Andrey Ryabinin
2019-09-12 14:08     ` Walter Wu
2019-09-12 14:31       ` Vlastimil Babka
2019-09-12 15:13         ` Walter Wu
2019-09-12 17:05         ` Andrey Ryabinin
2019-09-16  9:42           ` Vlastimil Babka
2019-09-16 15:57             ` Andrey Ryabinin [this message]
2019-09-17  8:19               ` Vlastimil Babka
2019-09-23  8:20               ` [PATCH] mm, debug, kasan: save and dump freeing stack trace for kasan Vlastimil Babka
2019-09-25  9:41                 ` Andrey Ryabinin
2019-09-12 14:10     ` [PATCH v3] mm/kasan: dump alloc and free stack for page allocator Qian Cai

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