From 8a2f7257ae6a7d1e1c87dd1ef146bd3e9c04e903 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 27 Apr 2012 08:42:53 -0700 Subject: [PATCH] percpu: pcpu_embed_first_chunk() should free unused parts after all allocs are complete commit 42b64281453249dac52861f9b97d18552a7ec62b upstream. pcpu_embed_first_chunk() allocates memory for each node, copies percpu data and frees unused portions of it before proceeding to the next group. This assumes that allocations for different nodes doesn't overlap; however, depending on memory topology, the bootmem allocator may end up allocating memory from a different node than the requested one which may overlap with the portion freed from one of the previous percpu areas. This leads to percpu groups for different nodes overlapping which is a serious bug. This patch separates out copy & partial free from the allocation loop such that all allocations are complete before partial frees happen. This also fixes overlapping frees which could happen on allocation failure path - out_free_areas path frees whole groups but the groups could have portions freed at that point. Signed-off-by: Tejun Heo Reported-by: "Pavel V. Panteleev" Tested-by: "Pavel V. Panteleev" LKML-Reference: Signed-off-by: Ben Hutchings --- mm/percpu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/percpu.c b/mm/percpu.c index 716eb4acf2fc..5c297506d8f4 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1642,6 +1642,16 @@ int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size, areas[group] = ptr; base = min(ptr, base); + } + + /* + * Copy data and free unused parts. This should happen after all + * allocations are complete; otherwise, we may end up with + * overlapping groups. + */ + for (group = 0; group < ai->nr_groups; group++) { + struct pcpu_group_info *gi = &ai->groups[group]; + void *ptr = areas[group]; for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) { if (gi->cpu_map[i] == NR_CPUS) { -- 2.39.2