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: update comments to reflect that percpu allocations are always zero-filled
  percpu: Optimize __get_cpu_var()
  x86, percpu: Optimize this_cpu_ptr
  percpu: clear memory allocated with the km allocator
  percpu: fix build breakage on s390 and cleanup build configuration tests
  percpu: use percpu allocator on UP too
  percpu: reduce PCPU_MIN_UNIT_SIZE to 32k
  vmalloc: pcpu_get/free_vm_areas() aren't needed on UP

Fixed up trivial conflicts in include/linux/percpu.h

10 files changed, 281 insertions, 236 deletions

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index cd28f9ad910d..f899e01a8ac9 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -47,6 +47,20 @@
 #ifdef CONFIG_SMP
 #define __percpu_arg(x)         "%%"__stringify(__percpu_seg)":%P" #x
 #define __my_cpu_offset         percpu_read(this_cpu_off)
+
+/*
+ * Compared to the generic __my_cpu_offset version, the following
+ * saves one instruction and avoids clobbering a temp register.
+ */
+#define __this_cpu_ptr(ptr)                             \
+({                                                      \
+        unsigned long tcp_ptr__;                        \
+        __verify_pcpu_ptr(ptr);                         \
+        asm volatile("add " __percpu_arg(1) ", %0"      \
+                     : "=r" (tcp_ptr__)                 \
+                     : "m" (this_cpu_off), "0" (ptr));  \
+        (typeof(*(ptr)) __kernel __force *)tcp_ptr__;   \
+})
 #else
 #define __percpu_arg(x)         "%P" #x
 #endif
diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 08923b684768..d17784ea37ff 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -55,14 +55,18 @@ extern unsigned long __per_cpu_offset[NR_CPUS];
  */
 #define per_cpu(var, cpu) \
         (*SHIFT_PERCPU_PTR(&(var), per_cpu_offset(cpu)))
-#define __get_cpu_var(var) \
-        (*SHIFT_PERCPU_PTR(&(var), my_cpu_offset))
-#define __raw_get_cpu_var(var) \
-        (*SHIFT_PERCPU_PTR(&(var), __my_cpu_offset))
 
-#define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
+#ifndef __this_cpu_ptr
 #define __this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset)
+#endif
+#ifdef CONFIG_DEBUG_PREEMPT
+#define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
+#else
+#define this_cpu_ptr(ptr) __this_cpu_ptr(ptr)
+#endif
 
+#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
+#define __raw_get_cpu_var(var) (*__this_cpu_ptr(&(var)))
 
 #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
 extern void setup_per_cpu_areas(void);
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 0eb50832aa00..5095b834a6fb 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -48,10 +48,8 @@
         preempt_enable();                               \
 } while (0)
 
-#ifdef CONFIG_SMP
-
 /* minimum unit size, also is the maximum supported allocation size */
-#define PCPU_MIN_UNIT_SIZE              PFN_ALIGN(64 << 10)
+#define PCPU_MIN_UNIT_SIZE              PFN_ALIGN(32 << 10)
 
 /*
  * Percpu allocator can serve percpu allocations before slab is
@@ -146,37 +144,20 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size,
  * dynamically allocated. Non-atomic access to the current CPU's
  * version should probably be combined with get_cpu()/put_cpu().
  */
+#ifdef CONFIG_SMP
 #define per_cpu_ptr(ptr, cpu)   SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
+#else
+#define per_cpu_ptr(ptr, cpu)   ({ (void)(cpu); VERIFY_PERCPU_PTR((ptr)); })
+#endif
 
 extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
 extern bool is_kernel_percpu_address(unsigned long addr);
 
-#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
+#if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
 extern void __init setup_per_cpu_areas(void);
 #endif
 extern void __init percpu_init_late(void);
 
-#else /* CONFIG_SMP */
-
-#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); VERIFY_PERCPU_PTR((ptr)); })
-
-/* can't distinguish from other static vars, always false */
-static inline bool is_kernel_percpu_address(unsigned long addr)
-{
-        return false;
-}
-
-static inline void __init setup_per_cpu_areas(void) { }
-
-static inline void __init percpu_init_late(void) { }
-
-static inline void *pcpu_lpage_remapped(void *kaddr)
-{
-        return NULL;
-}
-
-#endif /* CONFIG_SMP */
-
 extern void __percpu *__alloc_percpu(size_t size, size_t align);
 extern void free_percpu(void __percpu *__pdata);
 extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 01c2145118dc..63a4fe6d51bd 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -117,10 +117,12 @@ extern rwlock_t vmlist_lock;
 extern struct vm_struct *vmlist;
 extern __init void vm_area_register_early(struct vm_struct *vm, size_t align);
 
+#ifdef CONFIG_SMP
 struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
                                      const size_t *sizes, int nr_vms,
                                      size_t align, gfp_t gfp_mask);
 
 void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms);
+#endif
 
 #endif /* _LINUX_VMALLOC_H */
diff --git a/mm/Kconfig b/mm/Kconfig
index f0fb9124e410..c2c8a4a11898 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -301,3 +301,11 @@ config NOMMU_INITIAL_TRIM_EXCESS
           of 1 says that all excess pages should be trimmed.
 
           See Documentation/nommu-mmap.txt for more information.
+
+#
+# UP and nommu archs use km based percpu allocator
+#
+config NEED_PER_CPU_KM
+        depends on !SMP
+        bool
+        default y
diff --git a/mm/Makefile b/mm/Makefile
index 34b2546a9e37..f73f75a29f82 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -11,7 +11,7 @@ obj-y			:= bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
                            maccess.o page_alloc.o page-writeback.o \
                            readahead.o swap.o truncate.o vmscan.o shmem.o \
                            prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
-                           page_isolation.o mm_init.o mmu_context.o \
+                           page_isolation.o mm_init.o mmu_context.o percpu.o \
                            $(mmu-y)
 obj-y += init-mm.o
 
@@ -36,11 +36,6 @@ obj-$(CONFIG_FAILSLAB) += failslab.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
 obj-$(CONFIG_FS_XIP) += filemap_xip.o
 obj-$(CONFIG_MIGRATION) += migrate.o
-ifdef CONFIG_SMP
-obj-y += percpu.o
-else
-obj-y += percpu_up.o
-endif
 obj-$(CONFIG_QUICKLIST) += quicklist.o
 obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o page_cgroup.o
 obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o
diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index df680855540a..89633fefc6a2 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -27,7 +27,7 @@
  *   chunk size is not aligned.  percpu-km code will whine about it.
  */
 
-#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
 #error "contiguous percpu allocation is incompatible with paged first chunk"
 #endif
 
@@ -35,7 +35,11 @@
 
 static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
 {
-        /* noop */
+        unsigned int cpu;
+
+        for_each_possible_cpu(cpu)
+                memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
+
         return 0;
 }
 
diff --git a/mm/percpu.c b/mm/percpu.c
index c76ef3891e0d..6fc9015534f8 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -76,6 +76,7 @@
 #define PCPU_SLOT_BASE_SHIFT            5       /* 1-31 shares the same slot */
 #define PCPU_DFL_MAP_ALLOC              16      /* start a map with 16 ents */
 
+#ifdef CONFIG_SMP
 /* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
 #ifndef __addr_to_pcpu_ptr
 #define __addr_to_pcpu_ptr(addr)                                        \
@@ -89,6 +90,11 @@
                          (unsigned long)pcpu_base_addr -                \
                          (unsigned long)__per_cpu_start)
 #endif
+#else   /* CONFIG_SMP */
+/* on UP, it's always identity mapped */
+#define __addr_to_pcpu_ptr(addr)        (void __percpu *)(addr)
+#define __pcpu_ptr_to_addr(ptr)         (void __force *)(ptr)
+#endif  /* CONFIG_SMP */
 
 struct pcpu_chunk {
         struct list_head        list;           /* linked to pcpu_slot lists */
@@ -820,8 +826,8 @@ fail_unlock_mutex:
  * @size: size of area to allocate in bytes
  * @align: alignment of area (max PAGE_SIZE)
  *
- * Allocate percpu area of @size bytes aligned at @align.  Might
- * sleep.  Might trigger writeouts.
+ * Allocate zero-filled percpu area of @size bytes aligned at @align.
+ * Might sleep.  Might trigger writeouts.
  *
  * CONTEXT:
  * Does GFP_KERNEL allocation.
@@ -840,9 +846,10 @@ EXPORT_SYMBOL_GPL(__alloc_percpu);
  * @size: size of area to allocate in bytes
  * @align: alignment of area (max PAGE_SIZE)
  *
- * Allocate percpu area of @size bytes aligned at @align from reserved
- * percpu area if arch has set it up; otherwise, allocation is served
- * from the same dynamic area.  Might sleep.  Might trigger writeouts.
+ * Allocate zero-filled percpu area of @size bytes aligned at @align
+ * from reserved percpu area if arch has set it up; otherwise,
+ * allocation is served from the same dynamic area.  Might sleep.
+ * Might trigger writeouts.
  *
  * CONTEXT:
  * Does GFP_KERNEL allocation.
@@ -949,6 +956,7 @@ EXPORT_SYMBOL_GPL(free_percpu);
  */
 bool is_kernel_percpu_address(unsigned long addr)
 {
+#ifdef CONFIG_SMP
         const size_t static_size = __per_cpu_end - __per_cpu_start;
         void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
         unsigned int cpu;
@@ -959,6 +967,8 @@ bool is_kernel_percpu_address(unsigned long addr)
                 if ((void *)addr >= start && (void *)addr < start + static_size)
                         return true;
         }
+#endif
+        /* on UP, can't distinguish from other static vars, always false */
         return false;
 }
 
@@ -1067,161 +1077,6 @@ void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
 }
 
 /**
- * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
- * @reserved_size: the size of reserved percpu area in bytes
- * @dyn_size: minimum free size for dynamic allocation in bytes
- * @atom_size: allocation atom size
- * @cpu_distance_fn: callback to determine distance between cpus, optional
- *
- * This function determines grouping of units, their mappings to cpus
- * and other parameters considering needed percpu size, allocation
- * atom size and distances between CPUs.
- *
- * Groups are always mutliples of atom size and CPUs which are of
- * LOCAL_DISTANCE both ways are grouped together and share space for
- * units in the same group.  The returned configuration is guaranteed
- * to have CPUs on different nodes on different groups and >=75% usage
- * of allocated virtual address space.
- *
- * RETURNS:
- * On success, pointer to the new allocation_info is returned.  On
- * failure, ERR_PTR value is returned.
- */
-static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
-                                size_t reserved_size, size_t dyn_size,
-                                size_t atom_size,
-                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
-{
-        static int group_map[NR_CPUS] __initdata;
-        static int group_cnt[NR_CPUS] __initdata;
-        const size_t static_size = __per_cpu_end - __per_cpu_start;
-        int nr_groups = 1, nr_units = 0;
-        size_t size_sum, min_unit_size, alloc_size;
-        int upa, max_upa, uninitialized_var(best_upa);  /* units_per_alloc */
-        int last_allocs, group, unit;
-        unsigned int cpu, tcpu;
-        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_cnt));
-
-        /* calculate size_sum and ensure dyn_size is enough for early alloc */
-        size_sum = PFN_ALIGN(static_size + reserved_size +
-                            max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
-        dyn_size = size_sum - static_size - reserved_size;
-
-        /*
-         * Determine min_unit_size, alloc_size and max_upa such that
-         * alloc_size is multiple of atom_size and is the smallest
-         * which can accomodate 4k aligned segments which are equal to
-         * or larger than min_unit_size.
-         */
-        min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
-
-        alloc_size = roundup(min_unit_size, atom_size);
-        upa = alloc_size / min_unit_size;
-        while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
-                upa--;
-        max_upa = upa;
-
-        /* group cpus according to their proximity */
-        for_each_possible_cpu(cpu) {
-                group = 0;
-        next_group:
-                for_each_possible_cpu(tcpu) {
-                        if (cpu == tcpu)
-                                break;
-                        if (group_map[tcpu] == group && cpu_distance_fn &&
-                            (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
-                             cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
-                                group++;
-                                nr_groups = max(nr_groups, group + 1);
-                                goto next_group;
-                        }
-                }
-                group_map[cpu] = group;
-                group_cnt[group]++;
-        }
-
-        /*
-         * Expand unit size until address space usage goes over 75%
-         * and then as much as possible without using more address
-         * space.
-         */
-        last_allocs = INT_MAX;
-        for (upa = max_upa; upa; upa--) {
-                int allocs = 0, wasted = 0;
-
-                if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
-                        continue;
-
-                for (group = 0; group < nr_groups; group++) {
-                        int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
-                        allocs += this_allocs;
-                        wasted += this_allocs * upa - group_cnt[group];
-                }
-
-                /*
-                 * Don't accept if wastage is over 1/3.  The
-                 * greater-than comparison ensures upa==1 always
-                 * passes the following check.
-                 */
-                if (wasted > num_possible_cpus() / 3)
-                        continue;
-
-                /* and then don't consume more memory */
-                if (allocs > last_allocs)
-                        break;
-                last_allocs = allocs;
-                best_upa = upa;
-        }
-        upa = best_upa;
-
-        /* allocate and fill alloc_info */
-        for (group = 0; group < nr_groups; group++)
-                nr_units += roundup(group_cnt[group], upa);
-
-        ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
-        if (!ai)
-                return ERR_PTR(-ENOMEM);
-        cpu_map = ai->groups[0].cpu_map;
-
-        for (group = 0; group < nr_groups; group++) {
-                ai->groups[group].cpu_map = cpu_map;
-                cpu_map += roundup(group_cnt[group], upa);
-        }
-
-        ai->static_size = static_size;
-        ai->reserved_size = reserved_size;
-        ai->dyn_size = dyn_size;
-        ai->unit_size = alloc_size / upa;
-        ai->atom_size = atom_size;
-        ai->alloc_size = alloc_size;
-
-        for (group = 0, unit = 0; group_cnt[group]; group++) {
-                struct pcpu_group_info *gi = &ai->groups[group];
-
-                /*
-                 * Initialize base_offset as if all groups are located
-                 * back-to-back.  The caller should update this to
-                 * reflect actual allocation.
-                 */
-                gi->base_offset = unit * ai->unit_size;
-
-                for_each_possible_cpu(cpu)
-                        if (group_map[cpu] == group)
-                                gi->cpu_map[gi->nr_units++] = cpu;
-                gi->nr_units = roundup(gi->nr_units, upa);
-                unit += gi->nr_units;
-        }
-        BUG_ON(unit != nr_units);
-
-        return ai;
-}
-
-/**
  * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
  * @lvl: loglevel
  * @ai: allocation info to dump
@@ -1363,7 +1218,9 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 
         /* sanity checks */
         PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
+#ifdef CONFIG_SMP
         PCPU_SETUP_BUG_ON(!ai->static_size);
+#endif
         PCPU_SETUP_BUG_ON(!base_addr);
         PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
         PCPU_SETUP_BUG_ON(ai->unit_size & ~PAGE_MASK);
@@ -1488,6 +1345,8 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         return 0;
 }
 
+#ifdef CONFIG_SMP
+
 const char *pcpu_fc_names[PCPU_FC_NR] __initdata = {
         [PCPU_FC_AUTO]  = "auto",
         [PCPU_FC_EMBED] = "embed",
@@ -1515,8 +1374,180 @@ static int __init percpu_alloc_setup(char *str)
 }
 early_param("percpu_alloc", percpu_alloc_setup);
 
+/*
+ * pcpu_embed_first_chunk() is used by the generic percpu setup.
+ * Build it if needed by the arch config or the generic setup is going
+ * to be used.
+ */
 #if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
         !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
+#define BUILD_EMBED_FIRST_CHUNK
+#endif
+
+/* build pcpu_page_first_chunk() iff needed by the arch config */
+#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
+#define BUILD_PAGE_FIRST_CHUNK
+#endif
+
+/* pcpu_build_alloc_info() is used by both embed and page first chunk */
+#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
+/**
+ * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
+ * @reserved_size: the size of reserved percpu area in bytes
+ * @dyn_size: minimum free size for dynamic allocation in bytes
+ * @atom_size: allocation atom size
+ * @cpu_distance_fn: callback to determine distance between cpus, optional
+ *
+ * This function determines grouping of units, their mappings to cpus
+ * and other parameters considering needed percpu size, allocation
+ * atom size and distances between CPUs.
+ *
+ * Groups are always mutliples of atom size and CPUs which are of
+ * LOCAL_DISTANCE both ways are grouped together and share space for
+ * units in the same group.  The returned configuration is guaranteed
+ * to have CPUs on different nodes on different groups and >=75% usage
+ * of allocated virtual address space.
+ *
+ * RETURNS:
+ * On success, pointer to the new allocation_info is returned.  On
+ * failure, ERR_PTR value is returned.
+ */
+static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
+                                size_t reserved_size, size_t dyn_size,
+                                size_t atom_size,
+                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
+{
+        static int group_map[NR_CPUS] __initdata;
+        static int group_cnt[NR_CPUS] __initdata;
+        const size_t static_size = __per_cpu_end - __per_cpu_start;
+        int nr_groups = 1, nr_units = 0;
+        size_t size_sum, min_unit_size, alloc_size;
+        int upa, max_upa, uninitialized_var(best_upa);  /* units_per_alloc */
+        int last_allocs, group, unit;
+        unsigned int cpu, tcpu;
+        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_cnt));
+
+        /* calculate size_sum and ensure dyn_size is enough for early alloc */
+        size_sum = PFN_ALIGN(static_size + reserved_size +
+                            max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
+        dyn_size = size_sum - static_size - reserved_size;
+
+        /*
+         * Determine min_unit_size, alloc_size and max_upa such that
+         * alloc_size is multiple of atom_size and is the smallest
+         * which can accomodate 4k aligned segments which are equal to
+         * or larger than min_unit_size.
+         */
+        min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
+
+        alloc_size = roundup(min_unit_size, atom_size);
+        upa = alloc_size / min_unit_size;
+        while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
+                upa--;
+        max_upa = upa;
+
+        /* group cpus according to their proximity */
+        for_each_possible_cpu(cpu) {
+                group = 0;
+        next_group:
+                for_each_possible_cpu(tcpu) {
+                        if (cpu == tcpu)
+                                break;
+                        if (group_map[tcpu] == group && cpu_distance_fn &&
+                            (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
+                             cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
+                                group++;
+                                nr_groups = max(nr_groups, group + 1);
+                                goto next_group;
+                        }
+                }
+                group_map[cpu] = group;
+                group_cnt[group]++;
+        }
+
+        /*
+         * Expand unit size until address space usage goes over 75%
+         * and then as much as possible without using more address
+         * space.
+         */
+        last_allocs = INT_MAX;
+        for (upa = max_upa; upa; upa--) {
+                int allocs = 0, wasted = 0;
+
+                if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
+                        continue;
+
+                for (group = 0; group < nr_groups; group++) {
+                        int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
+                        allocs += this_allocs;
+                        wasted += this_allocs * upa - group_cnt[group];
+                }
+
+                /*
+                 * Don't accept if wastage is over 1/3.  The
+                 * greater-than comparison ensures upa==1 always
+                 * passes the following check.
+                 */
+                if (wasted > num_possible_cpus() / 3)
+                        continue;
+
+                /* and then don't consume more memory */
+                if (allocs > last_allocs)
+                        break;
+                last_allocs = allocs;
+                best_upa = upa;
+        }
+        upa = best_upa;
+
+        /* allocate and fill alloc_info */
+        for (group = 0; group < nr_groups; group++)
+                nr_units += roundup(group_cnt[group], upa);
+
+        ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
+        if (!ai)
+                return ERR_PTR(-ENOMEM);
+        cpu_map = ai->groups[0].cpu_map;
+
+        for (group = 0; group < nr_groups; group++) {
+                ai->groups[group].cpu_map = cpu_map;
+                cpu_map += roundup(group_cnt[group], upa);
+        }
+
+        ai->static_size = static_size;
+        ai->reserved_size = reserved_size;
+        ai->dyn_size = dyn_size;
+        ai->unit_size = alloc_size / upa;
+        ai->atom_size = atom_size;
+        ai->alloc_size = alloc_size;
+
+        for (group = 0, unit = 0; group_cnt[group]; group++) {
+                struct pcpu_group_info *gi = &ai->groups[group];
+
+                /*
+                 * Initialize base_offset as if all groups are located
+                 * back-to-back.  The caller should update this to
+                 * reflect actual allocation.
+                 */
+                gi->base_offset = unit * ai->unit_size;
+
+                for_each_possible_cpu(cpu)
+                        if (group_map[cpu] == group)
+                                gi->cpu_map[gi->nr_units++] = cpu;
+                gi->nr_units = roundup(gi->nr_units, upa);
+                unit += gi->nr_units;
+        }
+        BUG_ON(unit != nr_units);
+
+        return ai;
+}
+#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
+
+#if defined(BUILD_EMBED_FIRST_CHUNK)
 /**
  * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
  * @reserved_size: the size of reserved percpu area in bytes
@@ -1645,10 +1676,9 @@ out_free:
                 free_bootmem(__pa(areas), areas_size);
         return rc;
 }
-#endif /* CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK ||
-          !CONFIG_HAVE_SETUP_PER_CPU_AREA */
+#endif /* BUILD_EMBED_FIRST_CHUNK */
 
-#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+#ifdef BUILD_PAGE_FIRST_CHUNK
 /**
  * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
  * @reserved_size: the size of reserved percpu area in bytes
@@ -1756,10 +1786,11 @@ out_free_ar:
         pcpu_free_alloc_info(ai);
         return rc;
 }
-#endif /* CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK */
+#endif /* BUILD_PAGE_FIRST_CHUNK */
 
+#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
 /*
- * Generic percpu area setup.
+ * Generic SMP percpu area setup.
  *
  * The embedding helper is used because its behavior closely resembles
  * the original non-dynamic generic percpu area setup.  This is
@@ -1770,7 +1801,6 @@ out_free_ar:
  * on the physical linear memory mapping which uses large page
  * mappings on applicable archs.
  */
-#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
 EXPORT_SYMBOL(__per_cpu_offset);
 
@@ -1799,13 +1829,48 @@ void __init setup_per_cpu_areas(void)
                                     PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
                                     pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
         if (rc < 0)
-                panic("Failed to initialized percpu areas.");
+                panic("Failed to initialize percpu areas.");
 
         delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
         for_each_possible_cpu(cpu)
                 __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
 }
-#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
+#endif  /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
+
+#else   /* CONFIG_SMP */
+
+/*
+ * UP percpu area setup.
+ *
+ * UP always uses km-based percpu allocator with identity mapping.
+ * Static percpu variables are indistinguishable from the usual static
+ * variables and don't require any special preparation.
+ */
+void __init setup_per_cpu_areas(void)
+{
+        const size_t unit_size =
+                roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
+                                         PERCPU_DYNAMIC_RESERVE));
+        struct pcpu_alloc_info *ai;
+        void *fc;
+
+        ai = pcpu_alloc_alloc_info(1, 1);
+        fc = __alloc_bootmem(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+        if (!ai || !fc)
+                panic("Failed to allocate memory for percpu areas.");
+
+        ai->dyn_size = unit_size;
+        ai->unit_size = unit_size;
+        ai->atom_size = unit_size;
+        ai->alloc_size = unit_size;
+        ai->groups[0].nr_units = 1;
+        ai->groups[0].cpu_map[0] = 0;
+
+        if (pcpu_setup_first_chunk(ai, fc) < 0)
+                panic("Failed to initialize percpu areas.");
+}
+
+#endif  /* CONFIG_SMP */
 
 /*
  * First and reserved chunks are initialized with temporary allocation
diff --git a/mm/percpu_up.c b/mm/percpu_up.c
deleted file mode 100644
index db884fae5721..000000000000
--- a/mm/percpu_up.c
+++ /dev/null
@@ -1,30 +0,0 @@
-/*
- * mm/percpu_up.c - dummy percpu memory allocator implementation for UP
- */
-
-#include <linux/module.h>
-#include <linux/percpu.h>
-#include <linux/slab.h>
-
-void __percpu *__alloc_percpu(size_t size, size_t align)
-{
-        /*
-         * Can't easily make larger alignment work with kmalloc.  WARN
-         * on it.  Larger alignment should only be used for module
-         * percpu sections on SMP for which this path isn't used.
-         */
-        WARN_ON_ONCE(align > SMP_CACHE_BYTES);
-        return (void __percpu __force *)kzalloc(size, GFP_KERNEL);
-}
-EXPORT_SYMBOL_GPL(__alloc_percpu);
-
-void free_percpu(void __percpu *p)
-{
-        kfree(this_cpu_ptr(p));
-}
-EXPORT_SYMBOL_GPL(free_percpu);
-
-phys_addr_t per_cpu_ptr_to_phys(void *addr)
-{
-        return __pa(addr);
-}
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d8087f0db507..9f909622a25e 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2065,6 +2065,7 @@ void free_vm_area(struct vm_struct *area)
 }
 EXPORT_SYMBOL_GPL(free_vm_area);
 
+#ifdef CONFIG_SMP
 static struct vmap_area *node_to_va(struct rb_node *n)
 {
         return n ? rb_entry(n, struct vmap_area, rb_node) : NULL;
@@ -2345,6 +2346,7 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
                 free_vm_area(vms[i]);
         kfree(vms);
 }
+#endif  /* CONFIG_SMP */
 
 #ifdef CONFIG_PROC_FS
 static void *s_start(struct seq_file *m, loff_t *pos)