Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly
excluded pcpu_build_alloc_info() on SMP configurations which use
generic setup_per_cpu_area() like s390. The config ifdefs are
becoming confusing. Fix and clean it up by,
* Move pcpu_build_alloc_info() right on top of its two users -
pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP
block.
* Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each
first chunk function needs to be included and use them to control
inclusion of the three functions to reduce confusion.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reported-by: Sachin Sant <sachinp@xxxxxxxxxx>
---
Can you please test this patch?
Thanks.
mm/percpu.c | 338 +++++++++++++++++++++++++++++++-----------------------------
1 file changed, 175 insertions(+), 163 deletions(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index fa70122..0cd4bf6 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1075,165 +1075,6 @@ void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
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
- * @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 /* 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
* @lvl: loglevel
@@ -1532,8 +1373,180 @@ 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
@@ -1662,10 +1675,9 @@ 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
@@ -1773,7 +1785,7 @@ 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
/*
--
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