Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: make allocation failures more verbose
percpu: make pcpu_setup_first_chunk() failures more verbose
percpu: make embedding first chunk allocator check vmalloc space size
sparc64: implement page mapping percpu first chunk allocator
percpu: make pcpu_build_alloc_info() clear static buffers
percpu: fix unit_map[] verification in pcpu_setup_first_chunk()

arch/sparc/Kconfig

···
 config NEED_PER_CPU_EMBED_FIRST_CHUNK
 	def_bool y if SPARC64
 
+config NEED_PER_CPU_PAGE_FIRST_CHUNK
+	def_bool y if SPARC64
+
 config GENERIC_HARDIRQS_NO__DO_IRQ
 	bool
 	def_bool y if SPARC64

arch/sparc/kernel/smp_64.c

···
 	free_bootmem(__pa(ptr), size);
 }
 
-static int pcpu_cpu_distance(unsigned int from, unsigned int to)
+static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
 {
 	if (cpu_to_node(from) == cpu_to_node(to))
 		return LOCAL_DISTANCE;
···
 		return REMOTE_DISTANCE;
 }
 
+static void __init pcpu_populate_pte(unsigned long addr)
+{
+	pgd_t *pgd = pgd_offset_k(addr);
+	pud_t *pud;
+	pmd_t *pmd;
+
+	pud = pud_offset(pgd, addr);
+	if (pud_none(*pud)) {
+		pmd_t *new;
+
+		new = __alloc_bootmem(PAGE_SIZE, PAGE_SIZE, PAGE_SIZE);
+		pud_populate(&init_mm, pud, new);
+	}
+
+	pmd = pmd_offset(pud, addr);
+	if (!pmd_present(*pmd)) {
+		pte_t *new;
+
+		new = __alloc_bootmem(PAGE_SIZE, PAGE_SIZE, PAGE_SIZE);
+		pmd_populate_kernel(&init_mm, pmd, new);
+	}
+}
+
 void __init setup_per_cpu_areas(void)
 {
 	unsigned long delta;
 	unsigned int cpu;
-	int rc;
+	int rc = -EINVAL;
 
-	rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
-				    PERCPU_DYNAMIC_RESERVE, 4 << 20,
-				    pcpu_cpu_distance, pcpu_alloc_bootmem,
-				    pcpu_free_bootmem);
-	if (rc)
-		panic("failed to initialize first chunk (%d)", rc);
+	if (pcpu_chosen_fc != PCPU_FC_PAGE) {
+		rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
+					    PERCPU_DYNAMIC_RESERVE, 4 << 20,
+					    pcpu_cpu_distance,
+					    pcpu_alloc_bootmem,
+					    pcpu_free_bootmem);
+		if (rc)
+			pr_warning("PERCPU: %s allocator failed (%d), "
+				   "falling back to page size\n",
+				   pcpu_fc_names[pcpu_chosen_fc], rc);
+	}
+	if (rc < 0)
+		rc = pcpu_page_first_chunk(PERCPU_MODULE_RESERVE,
+					   pcpu_alloc_bootmem,
+					   pcpu_free_bootmem,
+					   pcpu_populate_pte);
+	if (rc < 0)
+		panic("cannot initialize percpu area (err=%d)", rc);
 
 	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
 	for_each_possible_cpu(cpu)

mm/percpu.c

···
  */
 static void *pcpu_alloc(size_t size, size_t align, bool reserved)
 {
+	static int warn_limit = 10;
 	struct pcpu_chunk *chunk;
+	const char *err;
 	int slot, off;
 
 	if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
···
 	if (reserved && pcpu_reserved_chunk) {
 		chunk = pcpu_reserved_chunk;
 		if (size > chunk->contig_hint ||
-		    pcpu_extend_area_map(chunk) < 0)
+		    pcpu_extend_area_map(chunk) < 0) {
+			err = "failed to extend area map of reserved chunk";
 			goto fail_unlock;
+		}
 		off = pcpu_alloc_area(chunk, size, align);
 		if (off >= 0)
 			goto area_found;
+		err = "alloc from reserved chunk failed";
 		goto fail_unlock;
 	}
 
···
 			case 1:
 				goto restart;	/* pcpu_lock dropped, restart */
 			default:
+				err = "failed to extend area map";
 				goto fail_unlock;
 			}
 
···
 	spin_unlock_irq(&pcpu_lock);
 
 	chunk = alloc_pcpu_chunk();
-	if (!chunk)
+	if (!chunk) {
+		err = "failed to allocate new chunk";
 		goto fail_unlock_mutex;
+	}
 
 	spin_lock_irq(&pcpu_lock);
 	pcpu_chunk_relocate(chunk, -1);
···
 	if (pcpu_populate_chunk(chunk, off, size)) {
 		spin_lock_irq(&pcpu_lock);
 		pcpu_free_area(chunk, off);
+		err = "failed to populate";
 		goto fail_unlock;
 	}
 
···
 	spin_unlock_irq(&pcpu_lock);
 fail_unlock_mutex:
 	mutex_unlock(&pcpu_alloc_mutex);
+	if (warn_limit) {
+		pr_warning("PERCPU: allocation failed, size=%zu align=%zu, "
+			   "%s\n", size, align, err);
+		dump_stack();
+		if (!--warn_limit)
+			pr_info("PERCPU: limit reached, disable warning\n");
+	}
 	return NULL;
 }
 
···
 	struct pcpu_alloc_info *ai;
 	unsigned int *cpu_map;
 
+	/* this function may be called multiple times */
+	memset(group_map, 0, sizeof(group_map));
+	memset(group_cnt, 0, sizeof(group_map));
+
 	/*
 	 * Determine min_unit_size, alloc_size and max_upa such that
 	 * alloc_size is multiple of atom_size and is the smallest
···
 int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 				  void *base_addr)
 {
+	static char cpus_buf[4096] __initdata;
 	static int smap[2], dmap[2];
 	size_t dyn_size = ai->dyn_size;
 	size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
···
 	int *unit_map;
 	int group, unit, i;
 
+	cpumask_scnprintf(cpus_buf, sizeof(cpus_buf), cpu_possible_mask);
+
+#define PCPU_SETUP_BUG_ON(cond)	do {					\
+	if (unlikely(cond)) {						\
+		pr_emerg("PERCPU: failed to initialize, %s", #cond);	\
+		pr_emerg("PERCPU: cpu_possible_mask=%s\n", cpus_buf);	\
+		pcpu_dump_alloc_info(KERN_EMERG, ai);			\
+		BUG();							\
+	}								\
+} while (0)
+
 	/* sanity checks */
 	BUILD_BUG_ON(ARRAY_SIZE(smap) >= PCPU_DFL_MAP_ALLOC ||
 		     ARRAY_SIZE(dmap) >= PCPU_DFL_MAP_ALLOC);
-	BUG_ON(ai->nr_groups <= 0);
-	BUG_ON(!ai->static_size);
-	BUG_ON(!base_addr);
-	BUG_ON(ai->unit_size < size_sum);
-	BUG_ON(ai->unit_size & ~PAGE_MASK);
-	BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
-
-	pcpu_dump_alloc_info(KERN_DEBUG, ai);
+	PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
+	PCPU_SETUP_BUG_ON(!ai->static_size);
+	PCPU_SETUP_BUG_ON(!base_addr);
+	PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
+	PCPU_SETUP_BUG_ON(ai->unit_size & ~PAGE_MASK);
+	PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
 
 	/* process group information and build config tables accordingly */
 	group_offsets = alloc_bootmem(ai->nr_groups * sizeof(group_offsets[0]));
···
 	unit_off = alloc_bootmem(nr_cpu_ids * sizeof(unit_off[0]));
 
 	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
-		unit_map[cpu] = NR_CPUS;
+		unit_map[cpu] = UINT_MAX;
 	pcpu_first_unit_cpu = NR_CPUS;
 
 	for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
···
 			if (cpu == NR_CPUS)
 				continue;
 
-			BUG_ON(cpu > nr_cpu_ids || !cpu_possible(cpu));
-			BUG_ON(unit_map[cpu] != NR_CPUS);
+			PCPU_SETUP_BUG_ON(cpu > nr_cpu_ids);
+			PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
+			PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
 
 			unit_map[cpu] = unit + i;
 			unit_off[cpu] = gi->base_offset + i * ai->unit_size;
···
 	pcpu_nr_units = unit;
 
 	for_each_possible_cpu(cpu)
-		BUG_ON(unit_map[cpu] == NR_CPUS);
+		PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
+
+	/* we're done parsing the input, undefine BUG macro and dump config */
+#undef PCPU_SETUP_BUG_ON
+	pcpu_dump_alloc_info(KERN_INFO, ai);
 
 	pcpu_nr_groups = ai->nr_groups;
 	pcpu_group_offsets = group_offsets;
···
 	void *base = (void *)ULONG_MAX;
 	void **areas = NULL;
 	struct pcpu_alloc_info *ai;
-	size_t size_sum, areas_size;
+	size_t size_sum, areas_size, max_distance;
 	int group, i, rc;
 
 	ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
···
 	}
 
 	/* base address is now known, determine group base offsets */
-	for (group = 0; group < ai->nr_groups; group++)
+	max_distance = 0;
+	for (group = 0; group < ai->nr_groups; group++) {
 		ai->groups[group].base_offset = areas[group] - base;
+		max_distance = max(max_distance, ai->groups[group].base_offset);
+	}
+	max_distance += ai->unit_size;
+
+	/* warn if maximum distance is further than 75% of vmalloc space */
+	if (max_distance > (VMALLOC_END - VMALLOC_START) * 3 / 4) {
+		pr_warning("PERCPU: max_distance=0x%lx too large for vmalloc "
+			   "space 0x%lx\n",
+			   max_distance, VMALLOC_END - VMALLOC_START);
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+		/* and fail if we have fallback */
+		rc = -EINVAL;
+		goto out_free;
+#endif
+	}
 
 	pr_info("PERCPU: Embedded %zu pages/cpu @%p s%zu r%zu d%zu u%zu\n",
 		PFN_DOWN(size_sum), base, ai->static_size, ai->reserved_size,