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Commit 74d46d6b authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
parent d6647bdf

arch/sparc/kernel/smp_64.c

+2 −2
Original line number Diff line number Diff line
@@ -1499,7 +1499,7 @@ void __init setup_per_cpu_areas(void) 
	dyn_size = pcpur_size - static_size - PERCPU_MODULE_RESERVE;





	ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));

	ptrs_size = PFN_ALIGN(nr_cpu_ids * sizeof(pcpur_ptrs[0]));

	pcpur_ptrs = alloc_bootmem(ptrs_size);



	for_each_possible_cpu(cpu) {
@@ -1514,7 +1514,7 @@ void __init setup_per_cpu_areas(void) 


	/* allocate address and map */

	vm.flags = VM_ALLOC;

	vm.size = num_possible_cpus() * PCPU_CHUNK_SIZE;

	vm.size = nr_cpu_ids * PCPU_CHUNK_SIZE;

	vm_area_register_early(&vm, PCPU_CHUNK_SIZE);



	for_each_possible_cpu(cpu) {

arch/x86/kernel/setup_percpu.c

+7 −7
Original line number Diff line number Diff line
@@ -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);

mm/percpu.c

+18 −15
Original line number Diff line number Diff line
@@ -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;



		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 */