On 07/15/2013 10:17 PM, Christoph Lameter wrote: > On Mon, 15 Jul 2013, Chen Gang wrote: > >> > On 07/12/2013 09:53 PM, Christoph Lameter wrote: >>> > > On Fri, 12 Jul 2013, Chen Gang wrote: >>> > > >>>> > >> Since all values which can be assigned to 'slub_debug' are 'unsigned >>>> > >> long', recommend also to define 'slub_debug' as 'unsigned long' to >>>> > >> match the type precisely >>> > > >>> > > The bit definitions in slab.h as well as slub.c all assume that these are >>> > > 32 bit entities. See f.e. the defition of the internal slub flags: >>> > > >>> > > /* Internal SLUB flags */ >>> > > #define __OBJECT_POISON 0x80000000UL /* Poison object */ >>> > > #define __CMPXCHG_DOUBLE 0x40000000UL /* Use cmpxchg_double */ >>> > > >> > >> > As far as I know, 'UL' means "unsigned long", is it correct ? > This is the way hex constants are generally specified. > > The C compiler will treat 'UL' as "unsigned long". If we really use 32-bit as unsigned number, better to use 'U' instead of 'UL' (e.g. 0x80000000U instead of 0x80000000UL). Since it is unsigned 32-bit number, it is better to use 'unsigned int' instead of 'int', which can avoid related warnings if "EXTRA_CFLAGS=-W". Thanks. -- Chen Gang -- 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>