[PATCH V2] powerpc/mm: Limit the max memory we can support
From: Aneesh Kumar K.V <hidden>
Date: 2015-05-29 08:21:33
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
We need to limit the max memory based on Linux page table format. Add checks to limit memory based on pte size. Also limit the memory based on MAX_PHSYSMEM_BITS. Signed-off-by: Aneesh Kumar K.V <redacted> --- Changes from V1: * Update commit message. 4K can handle 64TB * Also limit based on MAX_PHSYSMEM_BITS arch/powerpc/include/asm/mmu.h | 8 ++++++++ arch/powerpc/include/asm/sparsemem.h | 2 -- arch/powerpc/kernel/prom.c | 25 ++++++++++++++++++++++--- 3 files changed, 30 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 3d5abfe6ba67..d44d49093c8d 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h@@ -200,6 +200,14 @@ static inline void assert_pte_locked(struct mm_struct *mm, unsigned long addr) # include <asm/mmu-8xx.h> #endif +#ifdef CONFIG_PHYS_64BIT +/* + * Max supported memory on 64bit system is 64TB. + */ +#define MAX_PHYSMEM_BITS 46 +#else +#define MAX_PHYSMEM_BITS 32 +#endif #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_MMU_H_ */
diff --git a/arch/powerpc/include/asm/sparsemem.h b/arch/powerpc/include/asm/sparsemem.h
index f6fc0ee813d7..fc3808378893 100644
--- a/arch/powerpc/include/asm/sparsemem.h
+++ b/arch/powerpc/include/asm/sparsemem.h@@ -11,8 +11,6 @@ #define SECTION_SIZE_BITS 24 #define MAX_PHYSADDR_BITS 46 -#define MAX_PHYSMEM_BITS 46 - #endif /* CONFIG_SPARSEMEM */ #ifdef CONFIG_MEMORY_HOTPLUG
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 308c5e15676b..c09315b32ca7 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c@@ -698,9 +698,28 @@ void __init early_init_devtree(void *params) #endif reserve_crashkernel(); early_reserve_mem(); - - /* Ensure that total memory size is page-aligned. */ - limit = ALIGN(memory_limit ?: memblock_phys_mem_size(), PAGE_SIZE); + /* + * if not specified limit the memory based on the pfn count that + * we can fit in pte_t. Also ensure that total memory size is + * page-aligned. + */ + if (!memory_limit) { + int bit_count; + phys_addr_t pte_mem_limit; + + limit = memblock_phys_mem_size(); + if (limit >= (1ULL << MAX_PHYSMEM_BITS)) + limit = (1ULL << MAX_PHYSMEM_BITS) - 1; + + BUILD_BUG_ON(sizeof(pte_basic_t) > 8); + bit_count = (sizeof(pte_basic_t) * 8) - PTE_RPN_SHIFT + PAGE_SHIFT; + pte_mem_limit = ~0ULL >> (64 - bit_count); + if (limit > pte_mem_limit) + limit = pte_mem_limit; + } else + limit = memory_limit; + + limit = ALIGN(limit, PAGE_SIZE); memblock_enforce_memory_limit(limit); memblock_allow_resize();
--
2.1.4