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AHgh+Rpkx/RJcyAY6gd5L6ZSNsTEJeakCYihHqZGMdNmh8SKu4PsMTQ+vhUZ+V1BnxPoZ1dC+wKsZmx7+g==@kvack.org X-Gm-Message-State: AOJu0YyrQkHJQZ10GYAxHDOwZs2XRH6dMDTpR+CcJr6OxSbwOLS43bxN NRhVWIclBz68PMQmQoZVKvzAa6zB91h77pskczeG0xU3nCP71ntN6jtsOnv5XZAlVee/y/NypPR zL4z9xayMVwjPxRpyguIerYpYfg== X-Received: from pgmp19.prod.google.com ([2002:a63:1e53:0:b0:ca1:40df:1c8a]) (user=souravpanda job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:84e:b0:848:2f84:f427 with SMTP id d2e1a72fcca58-84e93338b86mr7855046b3a.64.1785342710351; Wed, 29 Jul 2026 09:31:50 -0700 (PDT) Date: Wed, 29 Jul 2026 16:31:48 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.508.g3f0d502094-goog Message-ID: <20260729163148.3271755-1-souravpanda@google.com> Subject: [PATCH v3] mm/hugetlb_cma: support percentage-based hugetlb_cma reservation From: Sourav Panda To: muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org Cc: david@kernel.org, usama.arif@linux.dev, surenb@google.com, fvdl@google.com, gthelen@google.com, rientjes@google.com, souravpanda@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: EC08520009 X-Stat-Signature: 3neckh5xs5bxtjes9cqk8qihz1qex4sj X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1785342711-59913 X-HE-Meta: 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 e/sEb+1A 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Currently, hugetlb_cma reservation only supports absolute sizes (e.g., hugetlb_cma=2G or hugetlb_cma=0:1G,1:1G). This can be restrictive in heterogeneous environments or when deploying common kernel command lines across machines with different memory capacities. Add support for percentage-based hugetlb_cma reservation (e.g., hugetlb_cma=20% or hugetlb_cma=0:20%,1:10%). The percentage is calculated against the total memory (for global settings) or against the node-specific memory (for node-specific settings) using memblock APIs during early boot. Signed-off-by: Sourav Panda --- Link: https://lore.kernel.org/linux-mm/20260628190155.3655895-1-souravpanda@google.com/ [v2] Link: https://lore.kernel.org/linux-mm/20260625215900.2151690-1-souravpanda@google.com/ [v1] v3: - Enhance pr_info logs to explicitly show percentage-derived sizes per Andrew Morton's suggestions. - Explicitly align percentage-derived sizes down to the gigantic page size to prevent allocation failures (Usama Arif). .../admin-guide/kernel-parameters.txt | 7 +- mm/hugetlb_cma.c | 126 ++++++++++++++++-- 2 files changed, 123 insertions(+), 10 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5a05b48d1684..846940ce2858 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2064,8 +2064,11 @@ Kernel parameters hugetlb_cma= [HW,CMA,EARLY] The size of a CMA area used for allocation of gigantic hugepages. Or using node format, the size of a CMA area per node can be specified. - Format: nn[KMGTPE] or (node format) - :nn[KMGTPE][,:nn[KMGTPE]] + The size can be an absolute value (e.g., 2G) or a + percentage of the total memory or node memory (e.g., 20%). + Format: nn[KMGTPE] or nn% or (node format) + :nn[KMGTPE][,:nn[KMGTPE]] or + :nn%[,:nn%] Reserve a CMA area of given size and allocate gigantic hugepages using the CMA allocator. If enabled, the diff --git a/mm/hugetlb_cma.c b/mm/hugetlb_cma.c index 7693ccefd0c6..99d05eb82abc 100644 --- a/mm/hugetlb_cma.c +++ b/mm/hugetlb_cma.c @@ -9,6 +9,9 @@ #include #include +#include +#include +#include #include "internal.h" #include "hugetlb_cma.h" @@ -18,6 +21,28 @@ static unsigned long hugetlb_cma_size_in_node[MAX_NUMNODES] __initdata; static bool hugetlb_cma_only __ro_after_init; static unsigned long hugetlb_cma_size __ro_after_init; +static unsigned int hugetlb_cma_percent __initdata; +static unsigned int hugetlb_cma_percent_in_node[MAX_NUMNODES] __initdata; + +#ifdef CONFIG_NUMA +static phys_addr_t __init memblock_node_memory_size(int nid) +{ + struct memblock_region *reg; + phys_addr_t size = 0; + + for_each_mem_region(reg) { + if (reg->nid == nid) + size += reg->size; + } + return size; +} +#else +static phys_addr_t __init memblock_node_memory_size(int nid) +{ + return memblock_phys_mem_size(); +} +#endif + void hugetlb_cma_free_frozen_folio(struct folio *folio) { WARN_ON_ONCE(!cma_release_frozen(hugetlb_cma[folio_nid(folio)], @@ -100,14 +125,28 @@ static int __init cmdline_parse_hugetlb_cma(char *p) break; if (s[count] == ':') { + char *next; + if (tmp >= MAX_NUMNODES) break; nid = array_index_nospec(tmp, MAX_NUMNODES); s += count + 1; - tmp = memparse(s, &s); - hugetlb_cma_size_in_node[nid] = tmp; - hugetlb_cma_size += tmp; + tmp = memparse(s, &next); + if (*next == '%') { + if (tmp > 100) { + pr_warn("hugetlb_cma: invalid percentage %lu for node %d\n", + tmp, nid); + break; + } + hugetlb_cma_percent_in_node[nid] = tmp; + hugetlb_cma_size_in_node[nid] = 0; + s = next + 1; + } else { + hugetlb_cma_size_in_node[nid] = tmp; + hugetlb_cma_percent_in_node[nid] = 0; + s = next; + } /* * Skip the separator if have one, otherwise @@ -118,7 +157,28 @@ static int __init cmdline_parse_hugetlb_cma(char *p) else break; } else { - hugetlb_cma_size = memparse(p, &p); + char *next; + + tmp = memparse(p, &next); + if (*next == '%') { + if (tmp > 100) { + pr_warn("hugetlb_cma: invalid percentage %lu\n", tmp); + } else { + hugetlb_cma_percent = tmp; + hugetlb_cma_size = 0; + for (nid = 0; nid < MAX_NUMNODES; nid++) { + hugetlb_cma_size_in_node[nid] = 0; + hugetlb_cma_percent_in_node[nid] = 0; + } + } + } else { + hugetlb_cma_size = tmp; + hugetlb_cma_percent = 0; + for (nid = 0; nid < MAX_NUMNODES; nid++) { + hugetlb_cma_size_in_node[nid] = 0; + hugetlb_cma_percent_in_node[nid] = 0; + } + } break; } } @@ -144,8 +204,36 @@ void __init hugetlb_cma_reserve(void) { unsigned long size, reserved, per_node, order; bool node_specific_cma_alloc = false; + bool has_node_specific_param = false; int nid; + for (nid = 0; nid < MAX_NUMNODES; nid++) { + if (hugetlb_cma_size_in_node[nid] || hugetlb_cma_percent_in_node[nid]) { + has_node_specific_param = true; + break; + } + } + + if (has_node_specific_param) { + hugetlb_cma_size = 0; + for (nid = 0; nid < MAX_NUMNODES; nid++) { + if (hugetlb_cma_percent_in_node[nid]) { + phys_addr_t node_gfp_mem = memblock_node_memory_size(nid); + u64 s; + + s = mul_u64_u32_div((u64)node_gfp_mem, + hugetlb_cma_percent_in_node[nid], + 100); + + hugetlb_cma_size_in_node[nid] = s; + } + hugetlb_cma_size += hugetlb_cma_size_in_node[nid]; + } + } else if (hugetlb_cma_percent) { + hugetlb_cma_size = mul_u64_u32_div((u64)memblock_phys_mem_size(), + hugetlb_cma_percent, 100); + } + if (!hugetlb_cma_size) return; @@ -163,6 +251,20 @@ void __init hugetlb_cma_reserve(void) */ VM_WARN_ON(order <= MAX_PAGE_ORDER); + if (hugetlb_cma_percent) { + hugetlb_cma_size = ALIGN_DOWN(hugetlb_cma_size, PAGE_SIZE << order); + } else if (has_node_specific_param) { + hugetlb_cma_size = 0; + for (nid = 0; nid < MAX_NUMNODES; nid++) { + if (hugetlb_cma_percent_in_node[nid]) { + hugetlb_cma_size_in_node[nid] = + ALIGN_DOWN(hugetlb_cma_size_in_node[nid], + PAGE_SIZE << order); + } + hugetlb_cma_size += hugetlb_cma_size_in_node[nid]; + } + } + hugetlb_bootmem_set_nodes(); for (nid = 0; nid < MAX_NUMNODES; nid++) { @@ -205,8 +307,12 @@ void __init hugetlb_cma_reserve(void) per_node = DIV_ROUND_UP(hugetlb_cma_size, nodes_weight(hugetlb_bootmem_nodes)); per_node = round_up(per_node, PAGE_SIZE << order); - pr_info("hugetlb_cma: reserve %lu MiB, up to %lu MiB per node\n", - hugetlb_cma_size / SZ_1M, per_node / SZ_1M); + if (hugetlb_cma_percent) + pr_info("hugetlb_cma: reserve %lu MiB (%u%%), up to %lu MiB per node\n", + hugetlb_cma_size / SZ_1M, hugetlb_cma_percent, per_node / SZ_1M); + else + pr_info("hugetlb_cma: reserve %lu MiB, up to %lu MiB per node\n", + hugetlb_cma_size / SZ_1M, per_node / SZ_1M); } reserved = 0; @@ -241,8 +347,12 @@ void __init hugetlb_cma_reserve(void) } reserved += size; - pr_info("hugetlb_cma: reserved %lu MiB on node %d\n", - size / SZ_1M, nid); + if (hugetlb_cma_percent_in_node[nid]) + pr_info("hugetlb_cma: reserved %lu MiB (%u%%) on node %d\n", + size / SZ_1M, hugetlb_cma_percent_in_node[nid], nid); + else + pr_info("hugetlb_cma: reserved %lu MiB on node %d\n", + size / SZ_1M, nid); if (reserved >= hugetlb_cma_size) break; -- 2.55.0.rc0.799.gd6f94ed593-goog