Re: [PATCH v4 5/7] mm, kasan: Stackdepot implementation. Enable stackdepot for SLAB
From: Steven Rostedt
Date: Fri Mar 11 2016 - 11:10:42 EST
On Fri, 11 Mar 2016 14:43:45 +0300
Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> wrote:
> >> This is not about size, this about fragmentation. vmalloc allows to
> >> utilize available low-order pages,
> >> hence reduce the fragmentation.
> > I've attempted to add __vmalloc(STACK_ALLOC_SIZE, alloc_flags,
> > PAGE_KERNEL) (also tried vmalloc(STACK_ALLOC_SIZE)) instead of
> > page_alloc() and am now getting a crash in
> > kmem_cache_alloc_node_trace() in mm/slab.c, because it doesn't allow
> > the kmem_cache pointer to be NULL (it's dereferenced when calling
> > trace_kmalloc_node()).
> > Steven, do you know if this because of my code violating some contract
> > (e.g. I'm calling vmalloc() too early, when kmalloc_caches haven't
> > been initialized),
> Probably. kmem_cache_init() goes before vmalloc_init().
Agreed, that function can not be called with cachep NULL, nor can it be
called before kmem_cache is set up to point to kmem_cache_boot.