From 1476cca098f6d3a553fcec6fe9b7d86e15c00b59 Mon Sep 17 00:00:00 2001 From: Alexander Graf Date: Fri, 21 Aug 2026 22:42:52 +0000 Subject: [PATCH] dma-contiguous: fix truncation of numa_cma / cma_pernuma sizes >= 2G numa_cma=0:4G reserves nothing at all. dma_numa_cma_reserve() copies the requested size into a local int before handing it to cma_declare_contiguous_nid(), so 0x100000000 truncates to zero and the loop skips the node silently. Both parameters are documented in kernel-parameters.txt as nn[MG], so that is the syntax the documentation invites. Which bits survive decides what a request turns into: 4G, 8G and 16G reserve nothing, 2G, 3G and 6G sign-extend into a size the allocator rejects with a warning, and 5G quietly reserves 1G. It reaches further than those parameters. On a CMA_SIZE_PERNUMA kernel with no per-node parameter, dma_numa_cma_reserve() takes the per-node size from the default area, so a plain cma=4G on a multi-node machine feeds that size through the same local and loses every per-node area. numa_cma_size[] and pernuma_size_bytes are both phys_addr_t, so use it for the local too, and give early_numa_cma() separate variables for the node id and the size while in there. Fixes: d5cae2261b86 ("dma-contiguous: simplify numa cma area handling") Cc: stable@vger.kernel.org Assisted-by: Kiro:claude-opus-5 Signed-off-by: Alexander Graf Reviewed-by: Feng Tang Link: https://lore.kernel.org/r/20260821224252.70640-1-graf@amazon.com Signed-off-by: Marek Szyprowski --- kernel/dma/contiguous.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index f754079a287d..66093460584e 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -140,21 +140,22 @@ static bool numa_cma_configured __initdata; static int __init early_numa_cma(char *p) { int nid, count = 0; - unsigned long tmp; + unsigned long node; + phys_addr_t size; char *s = p; while (*s) { - if (sscanf(s, "%lu%n", &tmp, &count) != 1) + if (sscanf(s, "%lu%n", &node, &count) != 1) break; if (s[count] == ':') { - if (tmp >= MAX_NUMNODES) + if (node >= MAX_NUMNODES) break; - nid = array_index_nospec(tmp, MAX_NUMNODES); + nid = array_index_nospec(node, MAX_NUMNODES); s += count + 1; - tmp = memparse(s, &s); - numa_cma_size[nid] = tmp; + size = memparse(s, &s); + numa_cma_size[nid] = size; if (*s == ',') s++; @@ -207,9 +208,10 @@ static void __init dma_numa_cma_reserve(void) pernuma_size_bytes = cma_get_size(dma_contiguous_default_area); for_each_node(nid) { - int size, ret; + phys_addr_t size; char name[CMA_MAX_NAME]; struct cma **cma; + int ret; if (!node_online(nid)) { if (pernuma_size_bytes || numa_cma_size[nid])