Re: [PATCH v2 3/5] kernel/power: allow hibernation with page_poison sanity checking

From: David Hildenbrand <david@redhat.com>
To: Vlastimil Babka <vbabka@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Alexander Potapenko <glider@google.com>,
	Kees Cook <keescook@chromium.org>,
	Michal Hocko <mhocko@kernel.org>,
	Mateusz Nosek <mateusznosek0@gmail.com>,
	Laura Abbott <labbott@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
	linux-pm@vger.kernel.org
Subject: Re: [PATCH v2 3/5] kernel/power: allow hibernation with page_poison sanity checking
Date: Thu, 12 Nov 2020 17:07:03 +0100	[thread overview]
Message-ID: <44ab29d4-4ad2-3142-0fcf-78897cf68c71@redhat.com> (raw)
In-Reply-To: <7811e5ec-c7ae-09a9-7f90-45e14956c4c4@suse.cz>

On 12.11.20 15:39, Vlastimil Babka wrote:
> On 11/11/20 4:42 PM, David Hildenbrand wrote:
> ...
>>> @@ -1152,12 +1152,18 @@ void clear_free_pages(void)
>>>    	if (WARN_ON(!(free_pages_map)))
>>>    		return;
>>>    
>>> -	if (IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) || want_init_on_free()) {
>>> +	if (page_poisoning_enabled() || want_init_on_free()) {
>>>    		memory_bm_position_reset(bm);
>>>    		pfn = memory_bm_next_pfn(bm);
>>>    		while (pfn != BM_END_OF_MAP) {
>>> -			if (pfn_valid(pfn))
>>> -				clear_highpage(pfn_to_page(pfn));
>>> +			if (pfn_valid(pfn)) {
>>> +				struct page *page = pfn_to_page(pfn);
>>
>> ^ empty line missing. And at least I prefer to declare all variables in
>> the function header.
>>
>> I'd even suggest to move this into a separate function like
>>
>> clear_or_poison_free_page(struct page *page)
>>
>>
> 
> Ok, fixup below.
> 
> ----8<----
>   From cae1e8ccfa57c28ed1b2f5f8a47319b86cbdcfbf Mon Sep 17 00:00:00 2001
> From: Vlastimil Babka <vbabka@suse.cz>
> Date: Thu, 12 Nov 2020 15:33:07 +0100
> Subject: [PATCH] kernel/power: allow hibernation with page_poison sanity
>    checking-fix
> 
> Adapt to __kernel_unpoison_pages fixup. Split out clear_or_poison_free_page()
> per David Hildenbrand.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
>    include/linux/mm.h      |  1 +
>    kernel/power/snapshot.c | 18 ++++++++++--------
>    2 files changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 861b9392b5dc..d4cfb06a611e 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2896,6 +2896,7 @@ static inline void kernel_unpoison_pages(struct page *page, int numpages)
>    #else
>    static inline bool page_poisoning_enabled(void) { return false; }
>    static inline bool page_poisoning_enabled_static(void) { return false; }
> +static inline void __kernel_poison_pages(struct page *page, int nunmpages) { }
>    static inline void kernel_poison_pages(struct page *page, int numpages) { }
>    static inline void kernel_unpoison_pages(struct page *page, int numpages) { }
>    #endif
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index 6b1c84afa891..a3491b29c5cc 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -1144,6 +1144,14 @@ void free_basic_memory_bitmaps(void)
>    	pr_debug("Basic memory bitmaps freed\n");
>    }
>    
> +static void clear_or_poison_free_page(struct page *page)
> +{
> +	if (page_poisoning_enabled_static())
> +		__kernel_poison_pages(page, 1);
> +	else if (want_init_on_free())
> +		clear_highpage(page);
> +}
> +
>    void clear_or_poison_free_pages(void)
>    {
>    	struct memory_bitmap *bm = free_pages_map;
> @@ -1156,14 +1164,8 @@ void clear_or_poison_free_pages(void)
>    		memory_bm_position_reset(bm);
>    		pfn = memory_bm_next_pfn(bm);
>    		while (pfn != BM_END_OF_MAP) {
> -			if (pfn_valid(pfn)) {
> -				struct page *page = pfn_to_page(pfn);
> -				if (page_poisoning_enabled_static())
> -					kernel_poison_pages(page, 1);
> -				else if (want_init_on_free())
> -					clear_highpage(page);
> -
> -			}
> +			if (pfn_valid(pfn))
> +				clear_or_poison_free_page(pfn_to_page(pfn));
>    
>    			pfn = memory_bm_next_pfn(bm);
>    		}
> 

LGTM, thanks!

-- 
Thanks,

David / dhildenb