Re: [PATCH v2 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@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: Re: [PATCH v2 0/2] x86/setup: consolidate early memory reservations
Date: Fri, 5 Feb 2021 21:47:54 +0200	[thread overview]
Message-ID: <20210205194754.GT242749@kernel.org> (raw)
In-Reply-To: <20210128105711.10428-1-rppt@kernel.org>

Hi,

Any comments on this?

On Thu, Jan 28, 2021 at 12:57:09PM +0200, Mike Rapoport wrote:
> 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.
> 
> v2:
> * get rid of trim_platform_memory_ranges() and call trim_snb_memory()
>   directly, per Boris comments
> * massage changelog and comments to use passive voice, per Boris
> * add Acked-by and Reviewed-by, thanks Boris and David
> 
> v1: https://lore.kernel.org/lkml/20210115083255.12744-1-rppt@kernel.org
> 
> Mike Rapoport (2):
>   x86/setup: consolidate early memory reservations
>   x86/setup: merge several reservations of start of the memory
> 
>  arch/x86/kernel/setup.c | 96 ++++++++++++++++++-----------------------
>  1 file changed, 42 insertions(+), 54 deletions(-)
> 
> -- 
> 2.28.0
> 

-- 
Sincerely yours,
Mike.