On Tue, Jan 24, 2017 at 12:35:39PM +0000, David Laight wrote: > From: Marcelo Ricardo Leitner > > Sent: 23 January 2017 16:03 > ... > > > > Does kcalloc() zero the entire area, or just the length you ask for? > > > > If the latter you need to zero the rest here. > > > Better still, just use krealloc. You still need to zero out any space > > > beyond > > > the old length, but it will make the code shorter, and avoid the need for > > > additional temporary variables. > > > > Seems if we pass gfp | __GFP_ZERO to krealloc it will end up zeroing the > > slab for us before doing the memcpy. > > I didn't follow all paths but in slab_alloc_node it will end up calling: > > if (unlikely(gfpflags & __GFP_ZERO) && object) > > memset(object, 0, s->object_size); > > So I would expect that other paths also do it. > > You probably don't want krealloc() zeroing all of the new area.
Yep, agreed. Marcelo
