linux-kernel - Re: [PATCH] mm, page_alloc: really disable DEBUG

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Message-ID: <892e685f-004b-88db-b1e6-a05c0c84b43a@suse.cz>
Date:   Wed, 19 May 2021 17:38:27 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Akinobu Mita <akinobu.mita@...il.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     David Hildenbrand <david@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Andrea Righi <andrea.righi@...onical.com>,
        Guilherme Piccoli <gpiccoli@...onical.com>
Subject: Re: [PATCH] mm, page_alloc: really disable DEBUG_PAGEALLOC with
 hibernation

On 5/19/21 5:28 PM, Krzysztof Kozlowski wrote:
> The documentation of DEBUG_PAGEALLOC states that it cannot be used with
> hibernation, however the Kconfig entry would allow it if
> ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC.
> 
> Fixes: ee3b4290aec0 ("generic debug pagealloc: build fix")
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>

Hmm the documentation seems wrong, as going through history it was indeed in
conflict only on PPC and SPARC.

> ---
>  mm/Kconfig.debug | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
> index 1e73717802f8..0ace5b2a9d04 100644
> --- a/mm/Kconfig.debug
> +++ b/mm/Kconfig.debug
> @@ -11,7 +11,7 @@ config PAGE_EXTENSION
>  config DEBUG_PAGEALLOC
>  	bool "Debug page memory allocations"
>  	depends on DEBUG_KERNEL
> -	depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
> +	depends on !HIBERNATION && ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
>  	select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
>  	help
>  	  Unmap pages from the kernel linear mapping after free_pages().
>