linux-kernel - Re: [PATCH v2] mm: teach dump_page() to correctly output poisoned struct pages

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Message-ID: <20180702185612.GJ19043@dhcp22.suse.cz>
Date:   Mon, 2 Jul 2018 20:56:12 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>
Cc:     steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        kirill.shutemov@...ux.intel.com, linux-mm@...ck.org,
        mgorman@...hsingularity.net, gregkh@...uxfoundation.org
Subject: Re: [PATCH v2] mm: teach dump_page() to correctly output poisoned
 struct pages

On Mon 02-07-18 14:05:36, Pavel Tatashin wrote:
[...]
>  void __dump_page(struct page *page, const char *reason)
>  {
> +	bool page_poisoned = PagePoisoned(page);
> +	int mapcount;
> +
> +	/*
> +	 * If struct page is poisoned don't access Page*() functions as that
> +	 * leads to recursive loop. Page*() check for poisoned pages, and calls
> +	 * dump_page() when detected.
> +	 */
> +	if (page_poisoned) {
> +		pr_emerg("page:%px is uninitialized and poisoned", page);
> +		goto hex_only;
> +	}

Thanks for the updated comment. Exactly what I was looking for!
-- 
Michal Hocko
SUSE Labs