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Tue, 25 Nov 2025 23:20:55 -0800 (PST) Received: from localhost ([2a03:2880:10ff:4e::]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7c78d30618bsm7229780a34.5.2025.11.25.23.20.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Nov 2025 23:20:55 -0800 (PST) From: Usama Arif To: rppt@kernel.org, Andrew Morton Cc: changyuanl@google.com, graf@amazon.com, leitao@debian.org, thevlad@meta.com, pratyush@kernel.org, dave.hansen@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, Usama Arif Subject: [PATCH] mm/memblock: only mark/clear KHO scratch memory when needed Date: Wed, 26 Nov 2025 07:20:51 +0000 Message-ID: <20251126072051.546700-1-usamaarif642@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The scratch memory for kexec handover is used to bootstrap the kexec'ed kernel. It is only needed when CONFIG_MEMBLOCK_KHO_SCRATCH is enabled (selected by KHO) and if it is a KHO boot. Add checks to prevent marking a KHO scratch region unless needed. kexec_handover.h is now unconditionally included for is_kho_boot. Fixes: a2daf83e10378 ("x86/e820: temporarily enable KHO scratch for memory = below 1M") Reported-by: Vlad Poenaru Signed-off-by: Usama Arif --- mm/memblock.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index e23e16618e9b3..5c85d575bb61c 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -20,8 +20,8 @@ =20 #ifdef CONFIG_KEXEC_HANDOVER #include -#include #endif /* CONFIG_KEXEC_HANDOVER */ +#include =20 #include #include @@ -1126,8 +1126,11 @@ int __init_memblock memblock_reserved_mark_noinit(ph= ys_addr_t base, phys_addr_t */ __init int memblock_mark_kho_scratch(phys_addr_t base, phys_addr_t size) { - return memblock_setclr_flag(&memblock.memory, base, size, 1, - MEMBLOCK_KHO_SCRATCH); + if (IS_ENABLED(CONFIG_MEMBLOCK_KHO_SCRATCH) && is_kho_boot()) + return memblock_setclr_flag(&memblock.memory, base, size, 1, + MEMBLOCK_KHO_SCRATCH); + else + return 0; } =20 /** @@ -1140,8 +1143,11 @@ __init int memblock_mark_kho_scratch(phys_addr_t bas= e, phys_addr_t size) */ __init int memblock_clear_kho_scratch(phys_addr_t base, phys_addr_t size) { - return memblock_setclr_flag(&memblock.memory, base, size, 0, - MEMBLOCK_KHO_SCRATCH); + if (IS_ENABLED(CONFIG_MEMBLOCK_KHO_SCRATCH) && is_kho_boot()) + return memblock_setclr_flag(&memblock.memory, base, size, 0, + MEMBLOCK_KHO_SCRATCH); + else + return 0; } =20 static bool should_skip_region(struct memblock_type *type, --=20 2.47.3