linux-kernel - Re: [PATCH v3 0/2] efi: Fix EFI boot with kexec handover (KHO)

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Message-Id: <20250821135809.c12105ca2a246a9fcb905af1@linux-foundation.org>
Date: Thu, 21 Aug 2025 13:58:09 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Evangelos Petrongonas <epetron@...zon.de>
Cc: Ard Biesheuvel <ardb@...nel.org>, Mike Rapoport <rppt@...nel.org>,
 Alexander Graf <graf@...zon.com>, Changyuan Lyu <changyuanl@...gle.com>,
 Baoquan He <bhe@...hat.com>, <kexec@...ts.infradead.org>,
 <linux-mm@...ck.org>, <linux-efi@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>, <nh-open-source@...zon.com>
Subject: Re: [PATCH v3 0/2] efi: Fix EFI boot with kexec handover (KHO)

On Thu, 21 Aug 2025 17:58:58 +0000 Evangelos Petrongonas <epetron@...zon.de> wrote:

> This patch series fixes a kernel panic that occurs when booting with
> both EFI and KHO (Kexec HandOver) enabled.
> 
> The issue arises because EFI's `reserve_regions()` clears all memory
> regions with `memblock_remove(0, PHYS_ADDR_MAX)` before rebuilding them
> from EFI data. This destroys KHO scratch regions that were set up early
> during device tree scanning, causing a panic as the kernel has no valid
> memory regions for early allocations.

Do you think we should backport this into 6.16.x kernels?  If so, is
there a suitable Fixes: target we can include?