[PATCH 5/6] x86,percpu: generalize lpage first chunk allocator

Tejun Heo
2009-06-17T04:07:43Z

Generalize and move x86 setup_pcpu_lpage() into
pcpu_lpage_first_chunk(). setup_pcpu_lpage() now is a simple wrapper
around the generalized version. Other than taking size parameters and
using arch supplied callbacks to allocate/free/map memory,
pcpu_lpage_first_chunk() is identical to the original implementation.

This simplifies arch code and will help converting more archs to
dynamic percpu allocator.

While at it, factor out pcpu_calc_fc_sizes() which is common to
pcpu_embed_first_chunk() and pcpu_lpage_first_chunk().

[ Impact: code reorganization and generalization ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
---
arch/x86/include/asm/percpu.h | 9 --
arch/x86/kernel/setup_percpu.c | 169 ++------------------------------
arch/x86/mm/pageattr.c | 1 +
include/linux/percpu.h | 27 +++++
mm/percpu.c | 209 +++++++++++++++++++++++++++++++++++++++-
5 files changed, 244 insertions(+), 171 deletions(-)

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 7e4111f..02ecb30 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -155,15 +155,6 @@ do { \
/* We can use this directly for local CPU (faster). */
DECLARE_PER_CPU(unsigned long, this_cpu_off);

-#ifdef CONFIG_NEED_MULTIPLE_NODES
-void *pcpu_lpage_remapped(void *kaddr);
-#else
-static inline void *pcpu_lpage_remapped(void *kaddr)
-{
- return NULL;
-}
-#endif
-
#endif /* !__ASSEMBLY__ */

#ifdef CONFIG_SMP
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index ab896b3..4f2e0ac 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -137,44 +137,21 @@ static void __init pcpu_fc_free(void *ptr, size_t size)
}

/*
- * Large page remap allocator
- *
- * This allocator uses PMD page as unit. A PMD page is allocated for
- * each cpu and each is remapped into vmalloc area using PMD mapping.
- * As PMD page is quite large, only part of it is used for the first
- * chunk. Unused part is returned to the bootmem allocator.
- *
- * So, the PMD pages are mapped twice - once to the physical mapping
- * and to the vmalloc area for the first percpu chunk. The double
- * mapping does add one more PMD TLB entry pressure but still is much
- * better than only using 4k mappings while still being NUMA friendly.
+ * Large page remapping allocator
*/
#ifdef CONFIG_NEED_MULTIPLE_NODES
-struct pcpul_ent {
- unsigned int cpu;
- void *ptr;
-};
-
-static size_t pcpul_size;
-static struct pcpul_ent *pcpul_map;
-static struct vm_struct pcpul_vm;
-
-static struct page * __init pcpul_get_page(unsigned int cpu, int pageno)
+static void __init pcpul_map(void *ptr, size_t size, void *addr)
{
- size_t off = (size_t)pageno << PAGE_SHIFT;
+ pmd_t *pmd, pmd_v;

- if (off >= pcpul_size)
- return NULL;
-
- return virt_to_page(pcpul_map[cpu].ptr + off);
+ pmd = populate_extra_pmd((unsigned long)addr);
+ pmd_v = pfn_pmd(page_to_pfn(virt_to_page(ptr)), PAGE_KERNEL_LARGE);
+ set_pmd(pmd, pmd_v);
}

static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
{
- size_t map_size, dyn_size;
- unsigned int cpu;
- int i, j;
- ssize_t ret;
+ size_t reserve = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;

if (!chosen) {
size_t vm_size = VMALLOC_END - VMALLOC_START;
@@ -198,134 +175,10 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
return -EINVAL;
}

- /*
- * Currently supports only single page. Supporting multiple
- * pages won't be too difficult if it ever becomes necessary.
- */
- pcpul_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
- PERCPU_DYNAMIC_RESERVE);
- if (pcpul_size > PMD_SIZE) {
- pr_warning("PERCPU: static data is larger than large page, "
- "can't use large page\n");
- return -EINVAL;
- }
- 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]));
- pcpul_map = alloc_bootmem(map_size);
-
- for_each_possible_cpu(cpu) {
- pcpul_map[cpu].cpu = cpu;
- pcpul_map[cpu].ptr = pcpu_alloc_bootmem(cpu, PMD_SIZE,
- PMD_SIZE);
- if (!pcpul_map[cpu].ptr) {
- pr_warning("PERCPU: failed to allocate large page "
- "for cpu%u\n", cpu);
- goto enomem;
- }
-
- /*
- * Only use pcpul_size bytes and give back the rest.
- *
- * Ingo: The 2MB up-rounding bootmem is needed to make
- * sure the partial 2MB page is still fully RAM - it's
- * not well-specified to have a PAT-incompatible area
- * (unmapped RAM, device memory, etc.) in that hole.
- */
- free_bootmem(__pa(pcpul_map[cpu].ptr + pcpul_size),
- PMD_SIZE - pcpul_size);
-
- memcpy(pcpul_map[cpu].ptr, __per_cpu_load, static_size);
- }
-
- /* allocate address and map */
- pcpul_vm.flags = VM_ALLOC;
- pcpul_vm.size = num_possible_cpus() * PMD_SIZE;
- vm_area_register_early(&pcpul_vm, PMD_SIZE);
-
- for_each_possible_cpu(cpu) {
- pmd_t *pmd, pmd_v;
-
- pmd = populate_extra_pmd((unsigned long)pcpul_vm.addr +
- cpu * PMD_SIZE);
- pmd_v = pfn_pmd(page_to_pfn(virt_to_page(pcpul_map[cpu].ptr)),
- PAGE_KERNEL_LARGE);
- set_pmd(pmd, pmd_v);
- }
-
- /* we're ready, commit */
- pr_info("PERCPU: Remapped at %p with large pages, static data "
- "%zu bytes\n", pcpul_vm.addr, static_size);
-
- ret = pcpu_setup_first_chunk(pcpul_get_page, static_size,
- PERCPU_FIRST_CHUNK_RESERVE, dyn_size,
- 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++)
- if (pcpul_map[i].ptr > pcpul_map[j].ptr) {
- struct pcpul_ent tmp = pcpul_map[i];
- pcpul_map[i] = pcpul_map[j];
- pcpul_map[j] = tmp;
- }
-
- return ret;
-
-enomem:
- for_each_possible_cpu(cpu)
- if (pcpul_map[cpu].ptr)
- free_bootmem(__pa(pcpul_map[cpu].ptr), pcpul_size);
- free_bootmem(__pa(pcpul_map), map_size);
- return -ENOMEM;
-}
-
-/**
- * pcpu_lpage_remapped - determine whether a kaddr is in pcpul recycled area
- * @kaddr: the kernel address in question
- *
- * Determine whether @kaddr falls in the pcpul recycled area. This is
- * used by pageattr to detect VM aliases and break up the pcpu PMD
- * mapping such that the same physical page is not mapped under
- * different attributes.
- *
- * The recycled area is always at the tail of a partially used PMD
- * page.
- *
- * RETURNS:
- * Address of corresponding remapped pcpu address if match is found;
- * otherwise, NULL.
- */
-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 pos;
-
- /* pcpul in use at all? */
- if (!pcpul_map)
- return NULL;
-
- /* okay, perform binary search */
- while (left <= right) {
- pos = (left + right) / 2;
-
- if (pcpul_map[pos].ptr < pmd_addr)
- left = pos + 1;
- else if (pcpul_map[pos].ptr > pmd_addr)
- right = pos - 1;
- else {
- /* it shouldn't be in the area for the first chunk */
- WARN_ON(offset < pcpul_size);
-
- return pcpul_vm.addr +
- pcpul_map[pos].cpu * PMD_SIZE + offset;
- }
- }
-
- return NULL;
+ return pcpu_lpage_first_chunk(static_size, PERCPU_FIRST_CHUNK_RESERVE,
+ reserve - PERCPU_FIRST_CHUNK_RESERVE,
+ PMD_SIZE,
+ pcpu_fc_alloc, pcpu_fc_free, pcpul_map);
}
#else
static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 9f9b8c2..29ce49d 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -12,6 +12,7 @@
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/pfn.h>
+#include <linux/percpu.h>

#include <asm/e820.h>
#include <asm/processor.h>
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 41b5bfa..9f6bfd7 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -62,6 +62,7 @@ typedef struct page * (*pcpu_get_page_fn_t)(unsigned int cpu, int pageno);
typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size);
typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
+typedef void (*pcpu_fc_map_fn_t)(void *ptr, size_t size, void *addr);

extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
size_t static_size, size_t reserved_size,
@@ -79,6 +80,32 @@ extern ssize_t __init pcpu_4k_first_chunk(
pcpu_fc_free_fn_t free_fn,
pcpu_fc_populate_pte_fn_t populate_pte_fn);

+#ifdef CONFIG_NEED_MULTIPLE_NODES
+extern ssize_t __init pcpu_lpage_first_chunk(
+ size_t static_size, size_t reserved_size,
+ ssize_t dyn_size, size_t lpage_size,
+ pcpu_fc_alloc_fn_t alloc_fn,
+ pcpu_fc_free_fn_t free_fn,
+ pcpu_fc_map_fn_t map_fn);
+
+extern void *pcpu_lpage_remapped(void *kaddr);
+#else
+static inline ssize_t __init pcpu_lpage_first_chunk(
+ size_t static_size, size_t reserved_size,
+ ssize_t dyn_size, size_t lpage_size,
+ pcpu_fc_alloc_fn_t alloc_fn,
+ pcpu_fc_free_fn_t free_fn,
+ pcpu_fc_map_fn_t map_fn)
+{
+ return -EINVAL;
+}
+
+static inline void *pcpu_lpage_remapped(void *kaddr)
+{
+ return NULL;
+}
+#endif
+
/*
* Use this to get to a cpu's version of the per-cpu object
* dynamically allocated. Non-atomic access to the current CPU's
diff --git a/mm/percpu.c b/mm/percpu.c
index c173763..17dfb7c 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1190,6 +1190,19 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
return pcpu_unit_size;
}

+static size_t pcpu_calc_fc_sizes(size_t static_size, size_t reserved_size,
+ ssize_t *dyn_sizep)
+{
+ size_t size_sum;
+
+ size_sum = PFN_ALIGN(static_size + reserved_size +
+ (*dyn_sizep >= 0 ? *dyn_sizep : 0));
+ if (*dyn_sizep != 0)
+ *dyn_sizep = size_sum - static_size - reserved_size;
+
+ return size_sum;
+}
+
/*
* Embedding first chunk setup helper.
*/
@@ -1241,10 +1254,7 @@ ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
unsigned int cpu;

/* determine parameters and allocate */
- pcpue_size = PFN_ALIGN(static_size + reserved_size +
- (dyn_size >= 0 ? dyn_size : 0));
- if (dyn_size != 0)
- dyn_size = pcpue_size - static_size - reserved_size;
+ pcpue_size = pcpu_calc_fc_sizes(static_size, reserved_size, &dyn_size);

pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
chunk_size = pcpue_unit_size * num_possible_cpus();
@@ -1391,6 +1401,197 @@ out_free_ar:
}

/*
+ * Large page remapping first chunk setup helper
+ */
+#ifdef CONFIG_NEED_MULTIPLE_NODES
+struct pcpul_ent {
+ unsigned int cpu;
+ void *ptr;
+};
+
+static size_t pcpul_size;
+static size_t pcpul_unit_size;
+static struct pcpul_ent *pcpul_map;
+static struct vm_struct pcpul_vm;
+
+static struct page * __init pcpul_get_page(unsigned int cpu, int pageno)
+{
+ size_t off = (size_t)pageno << PAGE_SHIFT;
+
+ if (off >= pcpul_size)
+ return NULL;
+
+ return virt_to_page(pcpul_map[cpu].ptr + off);
+}
+
+/**
+ * pcpu_lpage_first_chunk - remap the first percpu chunk using large page
+ * @static_size: the size of static percpu area in bytes
+ * @reserved_size: the size of reserved percpu area in bytes
+ * @dyn_size: free size for dynamic allocation in bytes, -1 for auto
+ * @lpage_size: the size of a large page
+ * @alloc_fn: function to allocate percpu lpage, always called with lpage_size
+ * @free_fn: function to free percpu memory, @size <= lpage_size
+ * @map_fn: function to map percpu lpage, always called with lpage_size
+ *
+ * This allocator uses large page as unit. A large page is allocated
+ * for each cpu and each is remapped into vmalloc area using large
+ * page mapping. As large page can be quite large, only part of it is
+ * used for the first chunk. Unused part is returned to the bootmem
+ * allocator.
+ *
+ * So, the large pages are mapped twice - once to the physical mapping
+ * and to the vmalloc area for the first percpu chunk. The double
+ * mapping does add one more large TLB entry pressure but still is
+ * much better than only using 4k mappings while still being NUMA
+ * friendly.
+ *
+ * RETURNS:
+ * The determined pcpu_unit_size which can be used to initialize
+ * percpu access on success, -errno on failure.
+ */
+ssize_t __init pcpu_lpage_first_chunk(size_t static_size, size_t reserved_size,
+ ssize_t dyn_size, size_t lpage_size,
+ pcpu_fc_alloc_fn_t alloc_fn,
+ pcpu_fc_free_fn_t free_fn,
+ pcpu_fc_map_fn_t map_fn)
+{
+ size_t size_sum;
+ size_t map_size;
+ unsigned int cpu;
+ int i, j;
+ ssize_t ret;
+
+ /*
+ * Currently supports only single page. Supporting multiple
+ * pages won't be too difficult if it ever becomes necessary.
+ */
+ size_sum = pcpu_calc_fc_sizes(static_size, reserved_size, &dyn_size);
+
+ pcpul_unit_size = lpage_size;
+ pcpul_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
+ if (pcpul_size > pcpul_unit_size) {
+ pr_warning("PERCPU: static data is larger than large page, "
+ "can't use large page\n");
+ return -EINVAL;
+ }
+
+ /* allocate pointer array and alloc large pages */
+ map_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpul_map[0]));
+ pcpul_map = alloc_bootmem(map_size);
+
+ for_each_possible_cpu(cpu) {
+ void *ptr;
+
+ ptr = alloc_fn(cpu, lpage_size);
+ if (!ptr) {
+ pr_warning("PERCPU: failed to allocate large page "
+ "for cpu%u\n", cpu);
+ goto enomem;
+ }
+
+ /*
+ * Only use pcpul_size bytes and give back the rest.
+ *
+ * Ingo: The lpage_size up-rounding bootmem is needed
+ * to make sure the partial lpage is still fully RAM -
+ * it's not well-specified to have a incompatible area
+ * (unmapped RAM, device memory, etc.) in that hole.
+ */
+ free_fn(ptr + pcpul_size, lpage_size - pcpul_size);
+
+ pcpul_map[cpu].cpu = cpu;
+ pcpul_map[cpu].ptr = ptr;
+
+ memcpy(ptr, __per_cpu_load, static_size);
+ }
+
+ /* allocate address and map */
+ pcpul_vm.flags = VM_ALLOC;
+ pcpul_vm.size = num_possible_cpus() * pcpul_unit_size;
+ vm_area_register_early(&pcpul_vm, pcpul_unit_size);
+
+ for_each_possible_cpu(cpu)
+ map_fn(pcpul_map[cpu].ptr, pcpul_unit_size,
+ pcpul_vm.addr + cpu * pcpul_unit_size);
+
+ /* we're ready, commit */
+ pr_info("PERCPU: Remapped at %p with large pages, static data "
+ "%zu bytes\n", pcpul_vm.addr, static_size);
+
+ ret = pcpu_setup_first_chunk(pcpul_get_page, static_size,
+ reserved_size, dyn_size, pcpul_unit_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++)
+ if (pcpul_map[i].ptr > pcpul_map[j].ptr) {
+ struct pcpul_ent tmp = pcpul_map[i];
+ pcpul_map[i] = pcpul_map[j];
+ pcpul_map[j] = tmp;
+ }
+
+ return ret;
+
+enomem:
+ for_each_possible_cpu(cpu)
+ if (pcpul_map[cpu].ptr)
+ free_fn(pcpul_map[cpu].ptr, pcpul_size);
+ free_bootmem(__pa(pcpul_map), map_size);
+ return -ENOMEM;
+}
+
+/**
+ * pcpu_lpage_remapped - determine whether a kaddr is in pcpul recycled area
+ * @kaddr: the kernel address in question
+ *
+ * Determine whether @kaddr falls in the pcpul recycled area. This is
+ * used by pageattr to detect VM aliases and break up the pcpu large
+ * page mapping such that the same physical page is not mapped under
+ * different attributes.
+ *
+ * The recycled area is always at the tail of a partially used large
+ * page.
+ *
+ * RETURNS:
+ * Address of corresponding remapped pcpu address if match is found;
+ * otherwise, NULL.
+ */
+void *pcpu_lpage_remapped(void *kaddr)
+{
+ unsigned long unit_mask = pcpul_unit_size - 1;
+ void *lpage_addr = (void *)((unsigned long)kaddr & ~unit_mask);
+ unsigned long offset = (unsigned long)kaddr & unit_mask;
+ int left = 0, right = num_possible_cpus() - 1;
+ int pos;
+
+ /* pcpul in use at all? */
+ if (!pcpul_map)
+ return NULL;
+
+ /* okay, perform binary search */
+ while (left <= right) {
+ pos = (left + right) / 2;
+
+ if (pcpul_map[pos].ptr < lpage_addr)
+ left = pos + 1;
+ else if (pcpul_map[pos].ptr > lpage_addr)
+ right = pos - 1;
+ else {
+ /* it shouldn't be in the area for the first chunk */
+ WARN_ON(offset < pcpul_size);
+
+ return pcpul_vm.addr +
+ pcpul_map[pos].cpu * pcpul_unit_size + offset;
+ }
+ }
+
+ return NULL;
+}
+#endif
+
+/*
* Generic percpu area setup.
*
* The embedding helper is used because its behavior closely resembles
--
1.6.0.2