On Tue, 2013-08-27 at 17:37 +0800, Tang Chen wrote: > memblock_alloc_base_nid() is a common API of memblock. And it calls > memblock_find_in_range_node() with %start = 0, which means it has no > limit for the lowest address by default. > > memblock_find_in_range_node(0, max_addr, size, align, nid); > > Since we introduced current_limit_low to memblock, if we have no limit > for the lowest address or we are not sure, we should pass > MEMBLOCK_ALLOC_ACCESSIBLE to %start so that it will be limited by the > default low limit. > > dma_contiguous_reserve() and setup_log_buf() will eventually call > memblock_alloc_base_nid() to allocate memory. So if the allocation order > is from low to high, they will allocate memory from the lowest limit > to higher memory. This requires the callers to use MEMBLOCK_ALLOC_ACCESSIBLE instead of 0. Is there a good way to make sure that all callers will follow this rule going forward? Perhaps, memblock_find_in_range_node() should emit some message if 0 is passed when current_order is low to high and the boot option is specified? Similarly, I wonder if we should have a check to the allocation size to make sure that all allocations will stay small in this case. Thanks, -Toshi > > Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx> > Reviewed-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx> > --- > mm/memblock.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 961d4a5..be8c4d1 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -851,7 +851,8 @@ 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); > > - found = memblock_find_in_range_node(0, max_addr, size, align, nid); > + found = memblock_find_in_range_node(MEMBLOCK_ALLOC_ACCESSIBLE, > + max_addr, size, align, nid); > if (found && !memblock_reserve(found, size)) > return found; > -- 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>