linux-kernel - [PATCH 0/2] x86/setup: consolidate early memory reservations

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Date:   Fri, 15 Jan 2021 10:32:53 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andrea Arcangeli <aarcange@...hat.com>,
        Baoquan He <bhe@...hat.com>, Borislav Petkov <bp@...en8.de>,
        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@...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: [PATCH 0/2] x86/setup: consolidate early memory reservations

From: Mike Rapoport <rppt@...ux.ibm.com>

Hi,

David noticed that we do some of memblock_reserve() calls after allocations
are possible:

https://lore.kernel.org/lkml/6ba6bde3-1520-5cd0-f987-32d543f0b79f@redhat.com

For now there is no actual problem because in top-down mode we allocate
from the end of the memory and in bottom-up mode we allocate above the
kernel image. But there is a patch in the mm tree that allow bottom-up
allocations below the kernel:

https://lore.kernel.org/lkml/20201217201214.3414100-2-guro@fb.com

and with this change we may get a memory corruption if an allocation steps
on some of the firmware areas that are yet to be reserved.

The below patches consolidate early memory reservations done during
setup_arch() so that memory used by firmware, bootloader, kernel text/data
and the memory that should be excluded from the available memory for
whatever other reason is reserved before memblock allocations are possible.

The patches are vs v5.11-rc3-mmots-2021-01-12-02-00 as I think they are
prerequisite for the memblock bottom-up changes, but if needed I can rebase
then on another tree.

Mike Rapoport (2):
  x86/setup: consolidate early memory reservations
  x86/setup: merge several reservations of start of the memory

 arch/x86/kernel/setup.c | 85 +++++++++++++++++++++--------------------
 1 file changed, 43 insertions(+), 42 deletions(-)

-- 
2.28.0