linux-kernel - Re: [PATCH 1/2] x86/setup: consolidate early memory reservations

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Message-ID: <20210125165643.GH23070@zn.tnic>
Date:   Mon, 25 Jan 2021 17:56:43 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Baoquan He <bhe@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...nel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>, Qian Cai <cai@....pw>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, x86@...nel.org
Subject: Re: [PATCH 1/2] x86/setup: consolidate early memory reservations

On Mon, Jan 25, 2021 at 05:31:14PM +0200, Mike Rapoport wrote:
> This would make sense but it's tricky. From memblock perspective,
> allocations are always allowed and it is the user responsibility to ensure
> all the early reservations are done before allocating memory.

Yah, I don't trust my users to know that for sure...

> So adding such a WARN would require a new memblock API and it's adoption by
> all architectures, which is way beyond the scope of this series :)

So definitely not for those series but I could imagine something like

memblock_reserve()
	
	if (memblock_allocations_allowed())
		WARN

or so. This way you don't need to touch the archtectures. It all depends
on what the other arches need/use.

Or you could even make that a new memblock_reserve_warn() thing or so
and wrap that functionality in it and have x86 call it only...

Anyway, something to that effect.

As to those two patches, you can add

Acked-by: Borislav Petkov <bp@...e.de>

to the next revision since akpm is going to take them.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette