Re: [PATCH] slab: fix /proc/slabinfo alignment

[Matthew Wilcox <willy@infradead.org>]

On Tue, Feb 20, 2018 at 10:23:41AM -0600, Christopher Lameter wrote:
> On Tue, 20 Feb 2018, Matthew Wilcox wrote:
> 
> > I don't think it's fixable; there's just too much information per slab.
> > Anyway, I preferred the solution you & I were working on to limit the
> > length of names to 16 bytes, except for the cgroup slabs.
> 
> So what do we do with the cgroup slab names? have a slabinfo per cgroup?

What I had in mind ...

struct kmem_cache_attr {
        const char name[16];
        unsigned int size;
        unsigned int align;
        unsigned int useroffset;
        unsigned int usersize;
        slab_flags_t flags;
        kmem_cache_ctor ctor;
}

struct kmem_cache {
        const struct kmem_cache_attr *a;
        const char *name;
	...
};

In kmem_cache_create_usercopy:

	s->name = a->name;

In memcg_create_kmem_cache:

	s->name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", a->name,
				css->serial_nr, memcg_name_buf);

In slab_kmem_cache_release:

	if (s->name != s->a->name)
		kfree_const(s->name);

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