From mboxrd@z Thu Jan 1 00:00:00 1970 From: b32955@freescale.com (Huang Shijie) Date: Thu, 13 Jun 2013 16:57:05 +0800 Subject: [PATCH 1/2] ARM: mmu: fix the hang when we steal a section unaligned size memory Message-ID: <1371113826-1231-1-git-send-email-b32955@freescale.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org If we want to steal 128K memory in the machine_desc->reserve() hook, we will hang up immediately. The hang reason is like this: [1] Stealing 128K makes the left memory is not aligned with the SECTION_SIZE. [2] So when the map_lowmem() tries to maps the lowmem memory banks, it will call the memblock_alloc(in early_alloc_aligned()) to allocate a page to store the pte. This pte page is in the unaligned region which is not mapped yet. [3] And when we use the memset() in the early_alloc_aligned(), we will hang right now. [4] The hang only occurs in the map_lowmem(). After the map_lowmem(), we have setup the PTE mappings. So in the later places, such as dma_contiguous_remap(), the hang will never occurs, This patch adds a global variable, in_map_lowmem, to check if we are in the map_lowmem() or not. If we are in the map_lowmem(), and we steal a SECTION_SIZE unaligned memory, we will use the memblock_alloc_base() to allocate the pte page. The @max_addr for memblock_alloc_base() is the last mapped address. Signed-off-by: Huang Shijie --- arch/arm/mm/mmu.c | 34 ++++++++++++++++++++++++++++++---- 1 files changed, 30 insertions(+), 4 deletions(-) diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index faa36d7..56d1a22 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -113,6 +113,8 @@ static struct cachepolicy cache_policies[] __initdata = { } }; +static bool in_map_lowmem __initdata; + #ifdef CONFIG_CPU_CP15 /* * These are useful for identifying cache coherency @@ -595,10 +597,32 @@ static void __init *early_alloc(unsigned long sz) return early_alloc_aligned(sz, sz); } -static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr, unsigned long prot) +static void __init *early_alloc_max_addr(unsigned long sz, phys_addr_t maddr) +{ + void *ptr; + + if (maddr == MEMBLOCK_ALLOC_ACCESSIBLE) + return early_alloc_aligned(sz, sz); + + ptr = __va(memblock_alloc_base(sz, sz, maddr)); + memset(ptr, 0, sz); + return ptr; +} + +static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr, + unsigned long end, unsigned long prot) { if (pmd_none(*pmd)) { - pte_t *pte = early_alloc(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE); + pte_t *pte; + phys_addr_t maddr = MEMBLOCK_ALLOC_ACCESSIBLE; + + if (in_map_lowmem && (end & SECTION_MASK)) { + end &= PGDIR_MASK; + BUG_ON(!end); + maddr = __virt_to_phys(end); + } + pte = early_alloc_max_addr(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE, + maddr); __pmd_populate(pmd, __pa(pte), prot); } BUG_ON(pmd_bad(*pmd)); @@ -609,7 +633,7 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr, unsigned long end, unsigned long pfn, const struct mem_type *type) { - pte_t *pte = early_pte_alloc(pmd, addr, type->prot_l1); + pte_t *pte = early_pte_alloc(pmd, addr, end, type->prot_l1); do { set_pte_ext(pte, pfn_pte(pfn, __pgprot(type->prot_pte)), 0); pfn++; @@ -1253,7 +1277,7 @@ static void __init kmap_init(void) { #ifdef CONFIG_HIGHMEM pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE), - PKMAP_BASE, _PAGE_KERNEL_TABLE); + PKMAP_BASE, 0, _PAGE_KERNEL_TABLE); #endif } @@ -1261,6 +1285,7 @@ static void __init map_lowmem(void) { struct memblock_region *reg; + in_map_lowmem = 1; /* Map all the lowmem memory banks. */ for_each_memblock(memory, reg) { phys_addr_t start = reg->base; @@ -1279,6 +1304,7 @@ static void __init map_lowmem(void) create_mapping(&map); } + in_map_lowmem = 0; } /* -- 1.7.1