From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 22 Mar 2011 19:34:09 +0000 Subject: [PATCH] ARM: memmap: only free allocated memmap entries when using SPARSEMEM Message-ID: <1300822449-7324-1-git-send-email-will.deacon@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. Cc: Russell King - ARM Linux Acked-by: Catalin Marinas Signed-off-by: Will Deacon --- arch/arm/mm/init.c | 16 +++++++++++++++- 1 files changed, 15 insertions(+), 1 deletions(-) diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index ce406e5..dfd4286 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -399,7 +399,7 @@ 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 @@ -433,6 +433,14 @@ 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. @@ -447,6 +455,12 @@ 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) -- 1.7.0.4