From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 18 May 2011 17:05:11 +0100 Subject: [PATCH] ARM: sparsemem: fix highmem detection when using SPARSEMEM Message-ID: <1305734711-6710-1-git-send-email-will.deacon@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org sanity_check_meminfo walks over the registered memory banks and attempts to split banks across lowmem and highmem when they would otherwise overlap with the vmalloc space. When SPARSEMEM is used, there are two potential problems that occur when the virtual address of the start of a bank is equal to vmalloc_min. 1.) The end of lowmem is calculated as __pa(vmalloc_min - 1) + 1. In the above scenario, this will give the end address of the previous bank, rather than the actual bank we are interested in. This value is later used as the memblock limit and artificially restricts the total amount of available memory. 2.) The checks to determine whether or not a bank belongs to highmem or not only check if __va(bank->start) is greater or less than vmalloc_min. In the case that it is equal, the bank is incorrectly treated as lowmem, which hoses the vmalloc area. This patch fixes these two problems by checking whether the virtual start address of a bank is >= vmalloc_min and then calculating lowmem_end by finding the virtual end address of the highest lowmem bank. Cc: Russell King Acked-by: Catalin Marinas Signed-off-by: Will Deacon --- Russell - I hit this problem on a RealView-PBX board when trying to use the full 1GB of memory with a 3:1 split configuration. arch/arm/mm/mmu.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 6cf76b3..9d8f0c8 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -765,15 +765,12 @@ static void __init sanity_check_meminfo(void) { int i, j, highmem = 0; - lowmem_limit = __pa(vmalloc_min - 1) + 1; - memblock_set_current_limit(lowmem_limit); - for (i = 0, j = 0; i < meminfo.nr_banks; i++) { struct membank *bank = &meminfo.bank[j]; *bank = meminfo.bank[i]; #ifdef CONFIG_HIGHMEM - if (__va(bank->start) > vmalloc_min || + if (__va(bank->start) >= vmalloc_min || __va(bank->start) < (void *)PAGE_OFFSET) highmem = 1; @@ -831,6 +828,9 @@ static void __init sanity_check_meminfo(void) bank->size = newsize; } #endif + if (!bank->highmem && bank->start + bank->size > lowmem_limit) + lowmem_limit = bank->start + bank->size; + j++; } #ifdef CONFIG_HIGHMEM @@ -854,6 +854,7 @@ static void __init sanity_check_meminfo(void) } #endif meminfo.nr_banks = j; + memblock_set_current_limit(lowmem_limit); } static inline void prepare_page_table(void) -- 1.7.0.4