Re: [PATCH v4 2/3] arm64: Support page mapping percpu first chunk allocator
From: Greg KH <gregkh@linuxfoundation.org>
Date: 2021-09-17 06:24:27
Also in:
linux-mm, lkml
On Fri, Sep 10, 2021 at 01:33:53PM +0800, Kefeng Wang wrote:
quoted hunk ↗ jump to hunk
Percpu embedded first chunk allocator is the firstly option, but it could fails on ARM64, eg, "percpu: max_distance=0x5fcfdc640000 too large for vmalloc space 0x781fefff0000" "percpu: max_distance=0x600000540000 too large for vmalloc space 0x7dffb7ff0000" "percpu: max_distance=0x5fff9adb0000 too large for vmalloc space 0x5dffb7ff0000" then we could meet "WARNING: CPU: 15 PID: 461 at vmalloc.c:3087 pcpu_get_vm_areas+0x488/0x838", even the system could not boot successfully. Let's implement page mapping percpu first chunk allocator as a fallback to the embedding allocator to increase the robustness of the system. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Kefeng Wang <redacted> --- arch/arm64/Kconfig | 4 ++ drivers/base/arch_numa.c | 82 +++++++++++++++++++++++++++++++++++----- 2 files changed, 76 insertions(+), 10 deletions(-)diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 077f2ec4eeb2..04cfe1b4e98b 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig@@ -1042,6 +1042,10 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK def_bool y depends on NUMA +config NEED_PER_CPU_PAGE_FIRST_CHUNK + def_bool y + depends on NUMA
Why is this a config option at all?
quoted hunk ↗ jump to hunk
+ source "kernel/Kconfig.hz" config ARCH_SPARSEMEM_ENABLEdiff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c index 46c503486e96..995dca9f3254 100644 --- a/drivers/base/arch_numa.c +++ b/drivers/base/arch_numa.c@@ -14,6 +14,7 @@ #include <linux/of.h> #include <asm/sections.h> +#include <asm/pgalloc.h> struct pglist_data *node_data[MAX_NUMNODES] __read_mostly; EXPORT_SYMBOL(node_data);@@ -168,22 +169,83 @@ static void __init pcpu_fc_free(void *ptr, size_t size) memblock_free_early(__pa(ptr), size); } +#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
Ick, no #ifdef in .c files if at all possible please.
+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(PAGE_SIZE, PAGE_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(PAGE_SIZE, PAGE_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(PAGE_SIZE, PAGE_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);That feels harsh, are you sure you want to crash? There's no way to recover from this? If not, how can this fail in real life?
+}
+#endif
+
void __init setup_per_cpu_areas(void)
{
unsigned long delta;
unsigned int cpu;
- int rc;
+ int rc = -EINVAL;
+
+ if (pcpu_chosen_fc != PCPU_FC_PAGE) {
+ /*
+ * Always reserve area for module percpu variables. That's
+ * what the legacy allocator did.
+ */
+ rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
+ PERCPU_DYNAMIC_RESERVE, PAGE_SIZE,
+ pcpu_cpu_distance,
+ pcpu_fc_alloc, pcpu_fc_free);
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+ if (rc < 0)
+ pr_warn("PERCPU: %s allocator failed (%d), falling back to page size\n",
+ pcpu_fc_names[pcpu_chosen_fc], rc);
+#endifWhy only print out a message for a config option? Again, no #ifdef in .c files if at all possible. thanks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel