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>

1 files changed, 7 insertions, 7 deletions

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 29a3eef7cf4a..07d81916f212 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -165,7 +165,7 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
 
         if (!chosen) {
                 size_t vm_size = VMALLOC_END - VMALLOC_START;
-                size_t tot_size = num_possible_cpus() * PMD_SIZE;
+                size_t tot_size = nr_cpu_ids * PMD_SIZE;
 
                 /* on non-NUMA, embedding is better */
                 if (!pcpu_need_numa())
@@ -199,7 +199,7 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
         dyn_size = pcpul_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
 
         /* allocate pointer array and alloc large pages */
-        map_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpul_map[0]));
+        map_size = PFN_ALIGN(nr_cpu_ids * sizeof(pcpul_map[0]));
         pcpul_map = alloc_bootmem(map_size);
 
         for_each_possible_cpu(cpu) {
@@ -228,7 +228,7 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
 
         /* allocate address and map */
         pcpul_vm.flags = VM_ALLOC;
-        pcpul_vm.size = num_possible_cpus() * PMD_SIZE;
+        pcpul_vm.size = nr_cpu_ids * PMD_SIZE;
         vm_area_register_early(&pcpul_vm, PMD_SIZE);
 
         for_each_possible_cpu(cpu) {
@@ -250,8 +250,8 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
                                      PMD_SIZE, pcpul_vm.addr, NULL);
 
         /* sort pcpul_map array for pcpu_lpage_remapped() */
-        for (i = 0; i < num_possible_cpus() - 1; i++)
-                for (j = i + 1; j < num_possible_cpus(); j++)
+        for (i = 0; i < nr_cpu_ids - 1; i++)
+                for (j = i + 1; j < nr_cpu_ids; j++)
                         if (pcpul_map[i].ptr > pcpul_map[j].ptr) {
                                 struct pcpul_ent tmp = pcpul_map[i];
                                 pcpul_map[i] = pcpul_map[j];
@@ -288,7 +288,7 @@ void *pcpu_lpage_remapped(void *kaddr)
 {
         void *pmd_addr = (void *)((unsigned long)kaddr & PMD_MASK);
         unsigned long offset = (unsigned long)kaddr & ~PMD_MASK;
-        int left = 0, right = num_possible_cpus() - 1;
+        int left = 0, right = nr_cpu_ids - 1;
         int pos;
 
         /* pcpul in use at all? */
@@ -377,7 +377,7 @@ static ssize_t __init setup_pcpu_4k(size_t static_size)
         pcpu4k_nr_static_pages = PFN_UP(static_size);
 
         /* unaligned allocations can't be freed, round up to page size */
-        pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus()
+        pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * nr_cpu_ids
                                * sizeof(pcpu4k_pages[0]));
         pcpu4k_pages = alloc_bootmem(pages_size);