linux-kernel - Re: [PATCH 08/15] mips: switch to generic version of pte allocation

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Message-ID: <20190502190945.rrrxfxo3rbhgc3cx@pburton-laptop>
Date:   Thu, 2 May 2019 19:09:47 +0000
From:   Paul Burton <paul.burton@...s.com>
To:     Mike Rapoport <rppt@...ux.ibm.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Greentime Hu <green.hu@...il.com>,
        Guan Xuetao <gxt@....edu.cn>, Guo Ren <guoren@...nel.org>,
        Helge Deller <deller@....de>, Ley Foon Tan <lftan@...era.com>,
        Matthew Wilcox <willy@...radead.org>,
        Matt Turner <mattst88@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michal Hocko <mhocko@...e.com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Richard Kuo <rkuo@...eaurora.org>,
        Richard Weinberger <richard@....at>,
        Russell King <linux@...linux.org.uk>,
        Sam Creasey <sammy@...my.net>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-alpha@...r.kernel.org" <linux-alpha@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-hexagon@...r.kernel.org" <linux-hexagon@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-m68k@...ts.linux-m68k.org" <linux-m68k@...ts.linux-m68k.org>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        "linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
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        "nios2-dev@...ts.rocketboards.org" <nios2-dev@...ts.rocketboards.org>
Subject: Re: [PATCH 08/15] mips: switch to generic version of pte allocation

Hi Mike,

On Thu, May 02, 2019 at 06:28:35PM +0300, Mike Rapoport wrote:
> MIPS allocates kernel PTE pages with
> 
> 	__get_free_pages(GFP_KERNEL | __GFP_ZERO, PTE_ORDER)
> 
> and user PTE pages with
> 
> 	alloc_pages(GFP_KERNEL | __GFP_ZERO, PTE_ORDER)

That bit isn't quite true - we don't use __GFP_ZERO in pte_alloc_one() &
instead call clear_highpage() on the allocated page. Not that I have a
problem with using __GFP_ZERO - it seems like the more optimal choice.
It just might be worth mentioning the change & expected equivalent
behavior.

Otherwise:

    Acked-by: Paul Burton <paul.burton@...s.com>

Thanks,
    Paul