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ARM: 6890/1: memmap: only free allocated memmap entries when using SPARSEMEM

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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 <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon 2011-04-28 18:44:31 +01:00 committed by Russell King
parent 362607df9f
commit 9af386c8dc
1 changed files with 15 additions and 1 deletions
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16
arch/arm/mm/init.c
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@ -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)