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Tue, 18 Aug 2026 02:24:37 -0700 (PDT) From: Wandun Chen To: robh@kernel.org, saravanak@kernel.org, rppt@kernel.org, m.szyprowski@samsung.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: akpm@linux-foundation.org Subject: [PATCH v2 2/5] of: reserved_mem: reject static regions overlapping no-map memory Date: Tue, 18 Aug 2026 17:24:17 +0800 Message-ID: <20260818092420.2859026-3-chenwandun1@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260818092420.2859026-1-chenwandun1@gmail.com> References: <20260818092420.2859026-1-chenwandun1@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Wandun Chen Static no-map reserved-memory regions are marked in memblock.memory rather than memblock.reserved. So the reservation overlap check does not reject a static region that overlaps existing no-map memory. Both regions can then be initialized and hand the same physical memory to different reserved-memory drivers. So reject a static region that overlaps existing no-map memory. Sashiko found this issue in [1]. Fixes: 86588296acbf ("fdt: Properly handle "no-map" field in the memory region") Signed-off-by: Wandun Chen Link: https://sashiko.dev/#/message/20260814084718.29C341F000E9%40smtp.kernel.org [1] --- drivers/of/of_reserved_mem.c | 3 ++- include/linux/memblock.h | 1 + mm/memblock.c | 14 ++++++++++++++ 3 files changed, 17 insertions(+), 1 deletion(-) diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c index c6e73d710ee1..9fb2e4c29443 100644 --- a/drivers/of/of_reserved_mem.c +++ b/drivers/of/of_reserved_mem.c @@ -152,7 +152,8 @@ static int __init early_init_dt_reserve_memory(phys_addr_t base, * if the region isn't memory as it won't be mapped. */ if (memblock_overlaps_region(&memblock.memory, base, size) && - memblock_is_region_reserved(base, size)) + (memblock_is_region_reserved(base, size) || + memblock_overlaps_nomap(base, size))) return -EBUSY; return memblock_mark_nomap(base, size); diff --git a/include/linux/memblock.h b/include/linux/memblock.h index d62db9e776cf..27d68fbb3157 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -148,6 +148,7 @@ int memblock_physmem_add(phys_addr_t base, phys_addr_t size); void memblock_trim_memory(phys_addr_t align); unsigned long memblock_addrs_overlap(phys_addr_t base1, phys_addr_t size1, phys_addr_t base2, phys_addr_t size2); +bool memblock_overlaps_nomap(phys_addr_t base, phys_addr_t size); bool memblock_overlaps_region(struct memblock_type *type, phys_addr_t base, phys_addr_t size); bool memblock_validate_numa_coverage(unsigned long threshold_bytes); diff --git a/mm/memblock.c b/mm/memblock.c index 9ce86349a29f..4cabfe365ac4 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -202,6 +202,20 @@ memblock_addrs_overlap(phys_addr_t base1, phys_addr_t size1, phys_addr_t base2, return ((base1 < (base2 + size2)) && (base2 < (base1 + size1))); } +bool __init memblock_overlaps_nomap(phys_addr_t base, phys_addr_t size) +{ + struct memblock_region *region; + + memblock_cap_size(base, &size); + for_each_mem_region(region) { + if (memblock_is_nomap(region) && + memblock_addrs_overlap(base, size, region->base, region->size)) + return true; + } + + return false; +} + bool __init_memblock memblock_overlaps_region(struct memblock_type *type, phys_addr_t base, phys_addr_t size) { -- 2.43.0