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

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Date:   Mon, 2 Jul 2018 12:51:50 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>
Cc:     steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        linux-kernel@...r.kernel.org, kirill.shutemov@...ux.intel.com,
        mhocko@...e.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,  2 Jul 2018 14:05:36 -0400 Pavel Tatashin <pasha.tatashin@...cle.com> wrote:

> If struct page is poisoned, and uninitialized access is detected via
> PF_POISONED_CHECK(page) dump_page() is called to output the page. But,
> the dump_page() itself accesses struct page to determine how to print
> it, and therefore gets into a recursive loop.
> 
> For example:
> dump_page()
>  __dump_page()
>   PageSlab(page)
>    PF_POISONED_CHECK(page)
>     VM_BUG_ON_PGFLAGS(PagePoisoned(page), page)
>      dump_page() recursion loop.
> 
> Fixes: f165b378bbdf ("mm: uninitialized struct page poisoning sanity checking")
> 
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...cle.com>
> Acked-by: Michal Hocko <mhocko@...e.com>

Thanks.  I added a cc:stable to make sure this gets into 4.17.x.