linux-kernel - Re: [v4 3/6] mm: uninitialized struct page poisoning sanity checking

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Message-ID: <20180216092330.k7hutkvjmy7nope3@gmail.com>
Date:   Fri, 16 Feb 2018 10:23:30 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>
Cc:     steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        akpm@...ux-foundation.org, mgorman@...hsingularity.net,
        mhocko@...e.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, vbabka@...e.cz,
        bharata@...ux.vnet.ibm.com, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, dan.j.williams@...el.com,
        kirill.shutemov@...ux.intel.com, bhe@...hat.com
Subject: Re: [v4 3/6] mm: uninitialized struct page poisoning sanity checking


* Pavel Tatashin <pasha.tatashin@...cle.com> wrote:

> During boot we poison struct page memory in order to ensure that no one is
> accessing this memory until the struct pages are initialized in
> __init_single_page().
> 
> This patch adds more scrutiny to this checking by making sure that flags
> do not equal the poison pattern when they are accessed.  The pattern is all
> ones.
> 
> Since node id is also stored in struct page, and may be accessed quite
> early, we add this enforcement into page_to_nid() function as well.
> Note, this is applicable only when NODE_NOT_IN_PAGE_FLAGS=n
> 
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...cle.com>
> Reviewed-by: Ingo Molnar <mingo@...nel.org>
> Acked-by: Michal Hocko <mhocko@...e.com>

Please always start patch titles with a verb, i.e.:

 mm: Add uninitialized struct page poisoning sanity check

or so.

Thanks,

	Ingo