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

From: Mike Rapoport <rppt@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	Baoquan He <bhe@redhat.com>, Borislav Petkov <bp@alien8.de>,
	David Hildenbrand <david@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@kernel.org>,
	Mike Rapoport <rppt@kernel.org>,
	Mike Rapoport <rppt@linux.ibm.com>, Qian Cai <cai@lca.pw>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org
Subject: [PATCH 0/2] x86/setup: consolidate early memory reservations
Date: Fri, 15 Jan 2021 10:32:53 +0200	[thread overview]
Message-ID: <20210115083255.12744-1-rppt@kernel.org> (raw)

From: Mike Rapoport <rppt@linux.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