On Thu, Feb 21, 2013 at 12:10 PM, Vineet Gupta <Vineet.Gupta1@xxxxxxxxxxxx> 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 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 <vgupta@xxxxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Tejun Heo <tj@xxxxxxxxxx> > Cc: Yinghai Lu <yinghai@xxxxxxxxxx> > Cc: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: linux-mm@xxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > --- > 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); > + the checking should be put before round_up? > 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>