diff options
| -rw-r--r-- | arch/arm64/mm/mmu.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index ca6d4952b733..f293f2222f50 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1538,6 +1538,53 @@ static struct notifier_block prevent_bootmem_remove_nb = { .notifier_call = prevent_bootmem_remove_notifier, }; +/* + * This ensures that boot memory sections on the platform are online + * from early boot. Memory sections could not be prevented from being + * offlined, unless for some reason they are not online to begin with. + * This helps validate the basic assumption on which the above memory + * event notifier works to prevent boot memory section offlining and + * its possible removal. + */ +static void validate_bootmem_online(void) +{ + phys_addr_t start, end, addr; + struct mem_section *ms; + u64 i; + + /* + * Scanning across all memblock might be expensive + * on some big memory systems. Hence enable this + * validation only with DEBUG_VM. + */ + if (!IS_ENABLED(CONFIG_DEBUG_VM)) + return; + + for_each_mem_range(i, &start, &end) { + for (addr = start; addr < end; addr += (1UL << PA_SECTION_SHIFT)) { + ms = __pfn_to_section(PHYS_PFN(addr)); + + /* + * All memory ranges in the system at this point + * should have been marked as early sections. + */ + WARN_ON(!early_section(ms)); + + /* + * Memory notifier mechanism here to prevent boot + * memory offlining depends on the fact that each + * early section memory on the system is initially + * online. Otherwise a given memory section which + * is already offline will be overlooked and can + * be removed completely. Call out such sections. + */ + if (!online_section(ms)) + pr_err("Boot memory [%llx %llx] is offline, can be removed\n", + addr, addr + (1UL << PA_SECTION_SHIFT)); + } + } +} + static int __init prevent_bootmem_remove_init(void) { int ret = 0; @@ -1545,6 +1592,7 @@ static int __init prevent_bootmem_remove_init(void) if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE)) return ret; + validate_bootmem_online(); ret = register_memory_notifier(&prevent_bootmem_remove_nb); if (ret) pr_err("%s: Notifier registration failed %d\n", __func__, ret); |