percpu, sparc64: fix sparse possible cpu map handling
percpu code has been assuming num_possible_cpus() == nr_cpu_ids which
is incorrect if cpu_possible_map contains holes. This causes percpu
code to access beyond allocated memories and vmalloc areas. On a
sparc64 machine with cpus 0 and 2 (u60), this triggers the following
warning or fails boot.
WARNING: at /devel/tj/os/work/mm/vmalloc.c:106 vmap_page_range_noflush+0x1f0/0x240()
Modules linked in:
Call Trace:
[00000000004b17d0] vmap_page_range_noflush+0x1f0/0x240
[00000000004b1840] map_vm_area+0x20/0x60
[00000000004b1950] __vmalloc_area_node+0xd0/0x160
[0000000000593434] deflate_init+0x14/0xe0
[0000000000583b94] __crypto_alloc_tfm+0xd4/0x1e0
[00000000005844f0] crypto_alloc_base+0x50/0xa0
[000000000058b898] alg_test_comp+0x18/0x80
[000000000058dad4] alg_test+0x54/0x180
[000000000058af00] cryptomgr_test+0x40/0x60
[0000000000473098] kthread+0x58/0x80
[000000000042b590] kernel_thread+0x30/0x60
[0000000000472fd0] kthreadd+0xf0/0x160
---[ end trace 429b268a213317ba ]---
This patch fixes generic percpu functions and sparc64
setup_per_cpu_areas() so that they handle sparse cpu_possible_map
properly.
Please note that on x86, cpu_possible_map() doesn't contain holes and
thus num_possible_cpus() == nr_cpu_ids and this patch doesn't cause
any behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
diff --git a/mm/percpu.c b/mm/percpu.c
index b70f2ac..e0be114 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -8,12 +8,12 @@
*
* This is percpu allocator which can handle both static and dynamic
* areas. Percpu areas are allocated in chunks in vmalloc area. Each
- * chunk is consisted of num_possible_cpus() units and the first chunk
- * is used for static percpu variables in the kernel image (special
- * boot time alloc/init handling necessary as these areas need to be
- * brought up before allocation services are running). Unit grows as
- * necessary and all units grow or shrink in unison. When a chunk is
- * filled up, another chunk is allocated. ie. in vmalloc area
+ * chunk is consisted of nr_cpu_ids units and the first chunk is used
+ * for static percpu variables in the kernel image (special boot time
+ * alloc/init handling necessary as these areas need to be brought up
+ * before allocation services are running). Unit grows as necessary
+ * and all units grow or shrink in unison. When a chunk is filled up,
+ * another chunk is allocated. ie. in vmalloc area
*
* c0 c1 c2
* ------------------- ------------------- ------------
@@ -558,7 +558,7 @@
static void pcpu_unmap(struct pcpu_chunk *chunk, int page_start, int page_end,
bool flush_tlb)
{
- unsigned int last = num_possible_cpus() - 1;
+ unsigned int last = nr_cpu_ids - 1;
unsigned int cpu;
/* unmap must not be done on immutable chunk */
@@ -643,7 +643,7 @@
*/
static int pcpu_map(struct pcpu_chunk *chunk, int page_start, int page_end)
{
- unsigned int last = num_possible_cpus() - 1;
+ unsigned int last = nr_cpu_ids - 1;
unsigned int cpu;
int err;
@@ -1067,9 +1067,9 @@
PFN_UP(size_sum));
pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
- pcpu_chunk_size = num_possible_cpus() * pcpu_unit_size;
+ pcpu_chunk_size = nr_cpu_ids * pcpu_unit_size;
pcpu_chunk_struct_size = sizeof(struct pcpu_chunk)
- + num_possible_cpus() * pcpu_unit_pages * sizeof(struct page *);
+ + nr_cpu_ids * pcpu_unit_pages * sizeof(struct page *);
if (dyn_size < 0)
dyn_size = pcpu_unit_size - static_size - reserved_size;
@@ -1248,7 +1248,7 @@
} else
pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
- chunk_size = pcpue_unit_size * num_possible_cpus();
+ chunk_size = pcpue_unit_size * nr_cpu_ids;
pcpue_ptr = __alloc_bootmem_nopanic(chunk_size, PAGE_SIZE,
__pa(MAX_DMA_ADDRESS));
@@ -1259,12 +1259,15 @@
}
/* return the leftover and copy */
- for_each_possible_cpu(cpu) {
+ for (cpu = 0; cpu < nr_cpu_ids; cpu++) {
void *ptr = pcpue_ptr + cpu * pcpue_unit_size;
- free_bootmem(__pa(ptr + pcpue_size),
- pcpue_unit_size - pcpue_size);
- memcpy(ptr, __per_cpu_load, static_size);
+ if (cpu_possible(cpu)) {
+ free_bootmem(__pa(ptr + pcpue_size),
+ pcpue_unit_size - pcpue_size);
+ memcpy(ptr, __per_cpu_load, static_size);
+ } else
+ free_bootmem(__pa(ptr), pcpue_unit_size);
}
/* we're ready, commit */