linux-kernel - Re: [PATCH v2 1/2] x86/efi: don't allocate memmap through memblock after mm

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Date:   Thu, 5 Jan 2017 17:15:11 +0800
From:   Dave Young <dyoung@...hat.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Nicolai Stange <nicstange@...il.com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mika Penttilä <mika.penttila@...tfour.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH v2 1/2] x86/efi: don't allocate memmap through memblock
 after mm_init()

On 01/05/17 at 08:42am, Ingo Molnar wrote:
> 
> * Nicolai Stange <nicstange@...il.com> wrote:
> 
> > Matt Fleming <matt@...eblueprint.co.uk> writes:
> > 
> > > On Thu, 22 Dec, at 11:23:39AM, Nicolai Stange wrote:
> > >> So, after memblock is gone, allocations should be done through the "normal"
> > >> page allocator. Introduce a helper, efi_memmap_alloc() for this. Use
> > >> it from efi_arch_mem_reserve() and from efi_free_boot_services() as well.
> > >> 
> > >> Fixes: 4bc9f92e64c8 ("x86/efi-bgrt: Use efi_mem_reserve() to avoid copying image data")
> > >> Signed-off-by: Nicolai Stange <nicstange@...il.com>
> > 
> > > Could you also modify efi_fake_memmap() to use your new
> > > efi_memmap_alloc() function for consistency
> > 
> > Sure.
> > 
> > I'm planning to submit another set of patches addressing the (bounded)
> > memmap leaking in anything calling efi_memmap_unmap() though. In the
> > course of doing so, the memmap allocation sites will get touched anyway:
> > I'll have to store some information about how the memmap's memory has
> > been obtained.
> 
> Will that patch be intrusive?
> 
> If yes then we'll need to keep this a separate urgent patch to fix the v4.9 
> regression that Dan Williams reported. I can apply the fix to efi/urgent and get 
> it to Linus straight away if you guys agree.

Ditto question to Matt as I asked in reply to patch 2/2, can we move the
efi_mem_reserve to early code so that memblock is still usable and
consider to improve it in other way later?

> 
> Thanks,
> 
> 	Ingo
> --
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