From 9af386c8dc5a9dce56f36b484647ad6401758c85 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 28 Apr 2011 18:44:31 +0100 Subject: [PATCH] ARM: 6890/1: memmap: only free allocated memmap entries when using SPARSEMEM The SPARSEMEM code allocates memmap entries only for sections which are present (i.e. those which contain some valid memory). The membank checks in free_unused_memmap do not take this into account and can incorrectly attempt to free memory which is not allocated, resulting in a BUG() in the bootmem code. However, if memory is configured as follows: |<----section---->|<----hole---->|<----section---->| +--------+--------+--------------+--------+--------+ | bank 0 | unused | | bank 1 | unused | +--------+--------+--------------+--------+--------+ where a bank only occupies part of a section, the memmap allocated for the remainder of the section *can* be freed. This patch modifies the checks in free_unused_memmap so that only valid memmap entries are considered for removal. Acked-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/mm/init.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index e5f6fc428348..e591513bb53e 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -392,7 +392,7 @@ free_memmap(unsigned long start_pfn, unsigned long end_pfn) * Convert start_pfn/end_pfn to a struct page pointer. */ start_pg = pfn_to_page(start_pfn - 1) + 1; - end_pg = pfn_to_page(end_pfn); + end_pg = pfn_to_page(end_pfn - 1) + 1; /* * Convert to physical addresses, and @@ -426,6 +426,14 @@ static void __init free_unused_memmap(struct meminfo *mi) bank_start = bank_pfn_start(bank); +#ifdef CONFIG_SPARSEMEM + /* + * Take care not to free memmap entries that don't exist + * due to SPARSEMEM sections which aren't present. + */ + bank_start = min(bank_start, + ALIGN(prev_bank_end, PAGES_PER_SECTION)); +#endif /* * If we had a previous bank, and there is a space * between the current bank and the previous, free it. @@ -440,6 +448,12 @@ static void __init free_unused_memmap(struct meminfo *mi) */ prev_bank_end = ALIGN(bank_pfn_end(bank), MAX_ORDER_NR_PAGES); } + +#ifdef CONFIG_SPARSEMEM + if (!IS_ALIGNED(prev_bank_end, PAGES_PER_SECTION)) + free_memmap(prev_bank_end, + ALIGN(prev_bank_end, PAGES_PER_SECTION)); +#endif } static void __init free_highpages(void)