From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794479961; b=t0ZsInDZ41JapSnLnVHG40UqEKUHwEnS8iIXrYHj8czg5gsCHKc30DLvFr66CitCATRR vkP1bwHO0U0jm3+5sfnnnho66eKSC3smB3xN+8ViCDFf47qlhBAkTriKT1zlFeLjee+4o UgWJ6iOkxK+48jfIVrtM+v41lMCerSA29PtcbZh2Z2eRT71MFi5eq8AWgZi06PODOgZ0B 1YGfaWAq1m6tl9THlCiJCPU4nMkdCs/OeRk7msDmGK/gfgJNdfwVTLND+CXXUDHdSdbrv U5fBOxetvdQ7/yNjupqgjCs5IT9DOdBYNipdcHyILCWu2IJRw8OsQIUo/Ph2ul3OCLg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794479961; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer; bh=ajyrEiwf6H5409PUsnOKabsSDBay2mJauseGK/YVr4g=; b=RGXAYK01BI9liUM93jxbrYIN5H2kaZOdb4aVE1DA24WgGYBlCMR4mh9NAmVX+do+W9r4 8FpQPry1fZCt7Ljdv66pNuJnUbMM5TJ0Wid8GmGh8/GTSFDTfFRnGLl5DxkJ6+X7YKKqj EaAmsPBVmLBZyiP2FH/n4U+hkT6Cq1QnnnzphUrZe2swpM2U93Fcx9uiFA+WRu5ZacZHm dzz0aRb/c1CxcGlVye1UUdWpJ2uvOriDR3CLMPL0688tPUoUH6cpzGJRdOQJiaVTkrsJP RjhZF40UlJKOJfI+NOxFLxHBl5YqSVzkPj5njst8mlELPuCCxrVWF75fM9C4lyE3q7g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=acKLejRj; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1EE61606A333; Thu, 12 Nov 2026 10:39:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=acKLejRj Received: by smtp.kernel.org (Postfix) with ESMTPSA id C71081F00A05; Thu, 12 Nov 2026 10:39:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794479960; bh=ajyrEiwf6H5409PUsnOKabsSDBay2mJauseGK/YVr4g=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=acKLejRjKHzZpGXehTjroNWz7OSm/RDok9tQ6JeCy4clnmS39scEhM3NJqDBR4c1G /9CqECnzjjW9yG5sRRg4WjnpebCuoK5dcH5kfMYSunGvqi1dHTwEeu8keUWObmMPUx QS9jaxK3ppkWHarktYytg8jMcnkOoOCKAIkgy61kDAYYEsh0NMduPIb7jeg/+Xa7lo FMN7Bmslf5mDJfBPNOvu0vaMyLhx6W1fqbpsc37Io4ajwaXaruOz1t46sxq9x+hJ/X Cq/4j06UJGKwBbJdFF0gv/u26JU7vZIbdL+zlqnptiMZE3069uwTcGna0Gdl5rL+qg qwTNq+vG79kCw== From: "Mike Rapoport (Microsoft)" Date: Thu, 12 Nov 2026 12:38:56 +0200 Subject: [PATCH v3 4/5] kho: fix bootmem sizing X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261112-kho-bootmem-sizing-v3-4-f0c8d00295d5@kernel.org> References: <20261112-kho-bootmem-sizing-v3-0-f0c8d00295d5@kernel.org> In-Reply-To: <20261112-kho-bootmem-sizing-v3-0-f0c8d00295d5@kernel.org> To: Jonathan Corbet , Mike Rapoport , Pasha Tatashin , Pratyush Yadav Cc: Alexander Graf , Andrew Morton , Chen Pei , George Guo , Kexin Liu , Randy Dunlap , Shuah Khan , Sourabh Jain , kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Jose A. Perez de Azpillaga" , Mukesh Pilaniya X-Mailer: b4 0.16.1-dev Bootmem areas are sized from overlapping views of the memory reserved in memblock: * the global area is sized from all reserved memory, including memory allocated on specific nodes, so on NUMA systems everything allocated on a node is accounted in both the global area and the area of that node. * per-node sizes are calculated after the lowmem and the global areas are reserved. With CONFIG_NUMA=n all memblock regions belong to node 0, so the lowmem and the global areas are accounted in the size of node 0 area and scaled once again. As a result, bootmem is about twice bigger than it should be on NUMA systems and about four times bigger with CONFIG_NUMA=n. On small systems reservation of the bootmem may fail and then KHO gets disabled. Make the areas cover separate parts of the reserved memory: the lowmem area covers allocations below ARCH_LOW_ADDRESS_LIMIT, per-node areas cover allocations above it on each node and the global area covers allocations that are not bound to any node. Calculate all sizes before reserving any of the areas. With CONFIG_NUMA=n the global area becomes empty and it is not reserved. If ARCH_LOW_ADDRESS_LIMIT covers all memory, as may happen on arm64, any area can serve lowmem allocations, so don't reserve the lowmem area. Bootmem sizes in MiB in x86 QEMU VMs, before -> after: CONFIG_NUMA=y CONFIG_NUMA=n 1G, 1 node 176 -> 92 320 -> 80 4G, 1 node 508 -> 332 1264 -> 316 16G, 2 nodes 1268 -> 704 2944 -> 736 32G, 4 nodes 2296 -> 1224 5196 -> 1300 64G, 4 nodes 4344 -> 2248 9664 -> 2420 Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers") Reported-by: Kexin Liu Reported-by: George Guo Closes: https://lore.kernel.org/all/20260904025101.9959-1-dongtai.guo@linux.dev Reported-by: Sourabh Jain Closes: https://lore.kernel.org/all/20260922131217.698809-1-sourabhjain@linux.ibm.com Reviewed-by: Pasha Tatashin Reviewed-by: Jose A. Perez de Azpillaga Reviewed-by: Pratyush Yadav Reviewed-by: Mukesh Pilaniya Signed-off-by: Mike Rapoport (Microsoft) --- kernel/liveupdate/kexec_handover.c | 92 ++++++++++++++++++++++---------------- 1 file changed, 54 insertions(+), 38 deletions(-) diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index bbc9e644addc9..e9cefe22a6e6f 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -685,6 +685,7 @@ static unsigned int bootmem_scale __initdata = 200; static phys_addr_t bootmem_size_global __initdata; static phys_addr_t bootmem_size_pernode __initdata; static phys_addr_t bootmem_size_lowmem __initdata; +static phys_addr_t bootmem_size_node[MAX_NUMNODES] __initdata; static int __init kho_parse_bootmem_size(char *p) { @@ -760,29 +761,58 @@ static int __init kho_parse_bootmem_size(char *p) } early_param("kho_bootmem", kho_parse_bootmem_size); +static phys_addr_t __init reserved_mem_size(phys_addr_t limit, int nid) +{ + return memblock_reserved_kern_size(limit, nid) - + memblock_reserved_hugetlb_size(limit, nid); +} + +static phys_addr_t __init bootmem_scale_size(phys_addr_t size) +{ + return size * bootmem_scale / 100; +} + +/* + * The lowmem area covers allocations below ARCH_LOW_ADDRESS_LIMIT, per-node + * areas cover allocations above it on each node and the global area covers + * allocations that are not bound to any node. + * + * The reserved memory on a node and the total reserved memory include + * lowmem, so it is subtracted from both. + * + * If ARCH_LOW_ADDRESS_LIMIT covers all memory, any area can serve lowmem + * allocations and there is no lowmem area. + * + * All sizes must be calculated before any area is reserved, otherwise the + * areas reserved first will be accounted in the sizes of the others. + */ static void __init bootmem_size_update(void) { - /* - * If fixed sizes are not provided via command line, calculate them now. - * Remove HugeTLB allocations from it because they never get allocated - * from bootmem. - */ + int nid; + if (bootmem_scale) { - phys_addr_t size; - - size = memblock_reserved_kern_size(ARCH_LOW_ADDRESS_LIMIT, - NUMA_NO_NODE); - size -= memblock_reserved_hugetlb_size(ARCH_LOW_ADDRESS_LIMIT, - NUMA_NO_NODE); - size = size * bootmem_scale / 100; - bootmem_size_lowmem = size; - - size = memblock_reserved_kern_size(MEMBLOCK_ALLOC_ANYWHERE, - NUMA_NO_NODE); - size -= memblock_reserved_hugetlb_size(MEMBLOCK_ALLOC_ANYWHERE, - NUMA_NO_NODE); - size = size * bootmem_scale / 100 - bootmem_size_lowmem; - bootmem_size_global = size; + phys_addr_t low_limit = ARCH_LOW_ADDRESS_LIMIT; + phys_addr_t lowmem, global, size; + + if (low_limit >= memblock_end_of_DRAM() - 1) + low_limit = 0; + + lowmem = reserved_mem_size(low_limit, NUMA_NO_NODE); + global = reserved_mem_size(MEMBLOCK_ALLOC_ANYWHERE, NUMA_NO_NODE); + global -= lowmem; + + for_each_node_state(nid, N_MEMORY) { + size = reserved_mem_size(MEMBLOCK_ALLOC_ANYWHERE, nid) - + reserved_mem_size(low_limit, nid); + bootmem_size_node[nid] = bootmem_scale_size(size); + global -= size; + } + + bootmem_size_lowmem = bootmem_scale_size(lowmem); + bootmem_size_global = bootmem_scale_size(global); + } else { + for_each_node_state(nid, N_MEMORY) + bootmem_size_node[nid] = bootmem_size_pernode; } /* @@ -791,24 +821,10 @@ static void __init bootmem_size_update(void) */ bootmem_size_lowmem = round_up(bootmem_size_lowmem, BOOTMEM_ALIGNMENT_BYTES); bootmem_size_global = round_up(bootmem_size_global, BOOTMEM_ALIGNMENT_BYTES); -} - -static phys_addr_t __init bootmem_size_node(int nid) -{ - phys_addr_t size; - - if (bootmem_scale) { - size = memblock_reserved_kern_size(MEMBLOCK_ALLOC_ANYWHERE, - nid); - /* Do not count HugeTLB pages. */ - size -= memblock_reserved_hugetlb_size(MEMBLOCK_ALLOC_ANYWHERE, - nid); - size = size * bootmem_scale / 100; - } else { - size = bootmem_size_pernode; + for_each_node_state(nid, N_MEMORY) { + bootmem_size_node[nid] = round_up(bootmem_size_node[nid], + BOOTMEM_ALIGNMENT_BYTES); } - - return round_up(size, BOOTMEM_ALIGNMENT_BYTES); } bool kho_bootmem_overlap(phys_addr_t phys, size_t size) @@ -905,7 +921,7 @@ static void __init kho_reserve_bootmem(void) * memoryless nodes, as we can not allocate bootmem areas there. */ for_each_node_state(nid, N_MEMORY) { - if (kho_reserve_bootmem_area(bootmem_size_node(nid), + if (kho_reserve_bootmem_area(bootmem_size_node[nid], MEMBLOCK_ALLOC_ACCESSIBLE, nid)) { pr_err("Failed to reserve nid %d bootmem\n", nid); goto err_free_bootmem_areas; -- 2.53.0