On Friday 22 February 2013 12:57 AM, Yinghai Lu wrote: > [+Cc: hpa] > > On Thu, Feb 21, 2013 at 10:39 AM, Vineet Gupta > <[email protected]> wrote: >> 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 BUG_ON() if effective size for allocation (as passed by caller >> and/or computed after alignemtn rounding) is zero. > should we just make align to 1 instead of 0 ?
Where - you mean if user passes 0, just make it 1. Nah - it's better to complain and get the call site fixed ! > or BUG_ON(!align) instead? That could be done too but you would also need BUG_ON(!size) - to catch another API abuse. BUG_ON(!size) however catches both the cases. > >> 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 | 2 ++ >> 1 files changed, 2 insertions(+), 0 deletions(-) >> >> diff --git a/mm/memblock.c b/mm/memblock.c >> index 1bcd9b9..32b36d0 100644 >> --- a/mm/memblock.c >> +++ b/mm/memblock.c >> @@ -824,6 +824,8 @@ 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); >> >> + BUG_ON(!size); >> + >> 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/ -- 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/
