This came to light when calling memblock allocator from arc port (for copying flattended DT). If a "0" alignment is passed, the allocator round_up() call incorrectly rounds up the size to 0.
round_up(num, alignto) => ((num - 1) | (alignto -1)) + 1 While the obvious allocation failure causes kernel to panic, it is better to warn the caller to fix the code. Tejun suggested that instead of BUG_ON(!align) - which might be ineffective due to pending console init and such, it is better to WARN_ON, and continue the boot with a reasonable default align. Caller passing @size need not be handled similarly as the subsequent panic will indicate that anyhow. Signed-off-by: Vineet Gupta <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Tejun Heo <[email protected]> Cc: Yinghai Lu <[email protected]> Cc: Wanpeng Li <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: [email protected] Cc: [email protected] --- mm/memblock.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index 1bcd9b9..f3804bd 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -824,6 +824,9 @@ static phys_addr_t __init memblock_alloc_base_nid(phys_addr_t size, /* align @size to avoid excessive fragmentation on reserved array */ size = round_up(size, align); + if (WARN_ON(!align)) + align = __alignof__(long long); + found = memblock_find_in_range_node(0, max_addr, size, align, nid); if (found && !memblock_reserve(found, size)) return found; -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
