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: 0034d395f89d ("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.ku...@linux.ibm.com> --- arch/powerpc/Kconfig | 5 ++- arch/powerpc/kernel/setup_64.c | 62 ++++++++++++++++++++++++++++++++-- 2 files changed, 63 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 9fa23eb320ff..820365c42065 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -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" diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index eaddd53a0e13..6090d8290561 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -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" @@ -808,13 +809,58 @@ 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 @@ -826,8 +872,18 @@ 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); -- 2.26.2