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percpu, sparc64: fix sparse possible cpu map handling

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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>
This commit is contained in:
Tejun Heo
2009-07-21 17:11:50 +09:00
parent d6647bdf98
commit 74d46d6b2d
3 changed files with 27 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
mm/percpu.c
View File

@@ -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_free_area(struct pcpu_chunk *chunk, int freeme)
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 void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size,
*/
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 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
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 @@ ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
} 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 @@ ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
}
/* 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 */