percpu: use percpu allocator on UP too
On UP, percpu allocations were redirected to kmalloc. This has the
following problems.
* For certain amount of allocations (determined by
PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu
allocator can be used before the usual kernel memory allocator is
brought online. On SMP, this is used to initialize the kernel
memory allocator.
* percpu allocator honors alignment upto PAGE_SIZE but kmalloc()
doesn't. For example, workqueue makes use of larger alignments for
cpu_workqueues.
Currently, users of percpu allocators need to handle UP differently,
which is somewhat fragile and ugly. Other than small amount of
memory, there isn't much to lose by enabling percpu allocator on UP.
It can simply use kernel memory based chunk allocation which was added
for SMP archs w/o MMUs.
This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and
makes UP build use percpu-km. As percpu addresses and kernel
addresses are always identity mapped and static percpu variables don't
need any special treatment, nothing is arch dependent and mm/percpu.c
implements generic setup_per_cpu_areas() for UP.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/mm/percpu.c b/mm/percpu.c
index 58c572b..fa70122 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 */
@@ -949,6 +955,7 @@
*/
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 +966,8 @@
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;
}
@@ -1066,6 +1075,8 @@
free_bootmem(__pa(ai), ai->__ai_size);
}
+#if defined(CONFIG_SMP) && (defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
+ defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK))
/**
* pcpu_build_alloc_info - build alloc_info considering distances between CPUs
* @reserved_size: the size of reserved percpu area in bytes
@@ -1220,6 +1231,8 @@
return ai;
}
+#endif /* CONFIG_SMP && (CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK ||
+ CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) */
/**
* pcpu_dump_alloc_info - print out information about pcpu_alloc_info
@@ -1363,7 +1376,9 @@
/* 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 +1503,8 @@
return 0;
}
+#ifdef CONFIG_SMP
+
const char *pcpu_fc_names[PCPU_FC_NR] __initdata = {
[PCPU_FC_AUTO] = "auto",
[PCPU_FC_EMBED] = "embed",
@@ -1758,8 +1775,9 @@
}
#endif /* CONFIG_NEED_PER_CPU_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 +1788,6 @@
* 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 +1816,48 @@
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