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powerpc/64/mm: implement page mapping percpu first chunk allocator 

Implement page mapping percpu first chunk allocator as a fallback to
the embedding allocator. With 4K hash translation we limit our page
table range to 64TB and commit: 0034d395f8 ("powerpc/mm/hash64: Map all the
kernel regions in the same 0xc range") moved all kernel mapping to
that 64TB range. In-order to support sparse memory layout we need
to increase our linear mapping space and reduce other mappings.

With such a layout percpu embedded first chunk allocator will fail
because of small vmalloc range. Add a fallback to page mapping
percpu first chunk allocator for such failures.

The below dmesg output can be observed in such case.

 percpu: max_distance=0x1ffffef00000 too large for vmalloc space 0x10000000000
 PERCPU: auto allocator failed (-22), falling back to page size
 percpu: 40 4K pages/cpu s148816 r0 d15024

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200608070904.387440-2-aneesh.kumar@linux.ibm.com
This commit is contained in:
Aneesh Kumar K.V 2020-06-08 12:39:02 +05:30 committed by Michael Ellerman
parent 2a32abac88
commit eb553f1697
2 changed files with 63 additions and 4 deletions
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5
arch/powerpc/Kconfig
View File

@ -59,7 +59,10 @@ config HAVE_SETUP_PER_CPU_AREA
def_bool PPC64
config NEED_PER_CPU_EMBED_FIRST_CHUNK
def_bool PPC64
def_bool y if PPC64
config NEED_PER_CPU_PAGE_FIRST_CHUNK
def_bool y if PPC64
config NR_IRQS
int "Number of virtual interrupt numbers"

62
arch/powerpc/kernel/setup_64.c
View File

@ -66,6 +66,7 @@
#include <asm/feature-fixups.h>
#include <asm/kup.h>
#include <asm/early_ioremap.h>
#include <asm/pgalloc.h>
#include "setup.h"
@ -811,13 +812,58 @@ static int pcpu_cpu_distance(unsigned int from, unsigned int to)
unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(__per_cpu_offset);
static void __init pcpu_populate_pte(unsigned long addr)
{
pgd_t *pgd = pgd_offset_k(addr);
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
p4d = p4d_offset(pgd, addr);
if (p4d_none(*p4d)) {
pud_t *new;
new = memblock_alloc(PUD_TABLE_SIZE, PUD_TABLE_SIZE);
if (!new)
goto err_alloc;
p4d_populate(&init_mm, p4d, new);
}
pud = pud_offset(p4d, addr);
if (pud_none(*pud)) {
pmd_t *new;
new = memblock_alloc(PMD_TABLE_SIZE, PMD_TABLE_SIZE);
if (!new)
goto err_alloc;
pud_populate(&init_mm, pud, new);
}
pmd = pmd_offset(pud, addr);
if (!pmd_present(*pmd)) {
pte_t *new;
new = memblock_alloc(PTE_TABLE_SIZE, PTE_TABLE_SIZE);
if (!new)
goto err_alloc;
pmd_populate_kernel(&init_mm, pmd, new);
}
return;
err_alloc:
panic("%s: Failed to allocate %lu bytes align=%lx from=%lx\n",
__func__, PAGE_SIZE, PAGE_SIZE, PAGE_SIZE);
}
void __init setup_per_cpu_areas(void)
{
const size_t dyn_size = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;
size_t atom_size;
unsigned long delta;
unsigned int cpu;
int rc;
int rc = -EINVAL;
/*
* Linear mapping is one of 4K, 1M and 16M. For 4K, no need
@ -829,8 +875,18 @@ void __init setup_per_cpu_areas(void)
else
atom_size = 1 << 20;
rc = pcpu_embed_first_chunk(0, dyn_size, atom_size, pcpu_cpu_distance,
pcpu_alloc_bootmem, pcpu_free_bootmem);
if (pcpu_chosen_fc != PCPU_FC_PAGE) {
rc = pcpu_embed_first_chunk(0, dyn_size, atom_size, pcpu_cpu_distance,
pcpu_alloc_bootmem, pcpu_free_bootmem);
if (rc)
pr_warn("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(0, pcpu_alloc_bootmem, pcpu_free_bootmem,
pcpu_populate_pte);
if (rc < 0)
panic("cannot initialize percpu area (err=%d)", rc);