Re: [PATCH v3] slob: add size header to all allocations

Rustam Kovhaev
2021-11-16T23:19:55Z

On Tue, Nov 16, 2021 at 12:26:17PM +0100, Vlastimil Babka wrote:
> On 10/29/21 05:05, Rustam Kovhaev wrote:
> > Let's prepend both kmalloc() and kmem_cache_alloc() allocations with the
> > size header.
> > It simplifies the slab API and guarantees that both kmem_cache_alloc()
> > and kmalloc() memory could be freed by kfree().
> >
> > meminfo right after the system boot, x86-64 on xfs, without the patch:
> > Slab: 35456 kB
> >
> > the same, with the patch:
> > Slab: 36100 kB
> >
> > Link: https://lore.kernel.org/lkml/20210929212347.1139666-1-rkovhaev@gmail.com
> > Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
>
> Sorry for the late reply. I think we can further simplify this. We have:
>
> static void *slob_alloc(size_t size, gfp_t gfp, int align,
> int node, int align_offset)
>
> Previously there was one caller that passed size as unchanged, align_offset
> = 0, the other passed size + SLOB_HDR_SIZE, align_offset = SLOB_HDR_SIZE.
> Now both callers do the latter. We can drop the align_offset parameter and
> pass size unchanged. slob_alloc() can internally add SLOB_HDR_SIZE to size,
> and use SLOB_HDR_SIZE instead of align_offset.

Thank you, I'll send a v4.