Re: [PATCH bpf-next 0/5] bpf: BPF specific memory allocator.

[Christoph Hellwig <hch@infradead.org>]

I'd suggest you discuss you needs with the slab mainainers and the mm
community firs.

On Wed, Jun 22, 2022 at 05:32:25PM -0700, Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@kernel.org>
> 
> Introduce any context BPF specific memory allocator.
> 
> Tracing BPF programs can attach to kprobe and fentry. Hence they
> run in unknown context where calling plain kmalloc() might not be safe.
> Front-end kmalloc() with per-cpu per-bucket cache of free elements.
> Refill this cache asynchronously from irq_work.
> 
> There is a lot more work ahead, but this set is useful base.
> Future work:
> - get rid of call_rcu in hash map
> - get rid of atomic_inc/dec in hash map
> - tune watermarks per allocation size
> - adopt this approach alloc_percpu_gfp
> - expose bpf_mem_alloc as uapi FD to be used in dynptr_alloc, kptr_alloc
> - add sysctl to force bpf_mem_alloc in hash map when safe even if pre-alloc
>   requested to reduce memory consumption
> - convert lru map to bpf_mem_alloc
> 
> Alexei Starovoitov (5):
>   bpf: Introduce any context BPF specific memory allocator.
>   bpf: Convert hash map to bpf_mem_alloc.
>   selftests/bpf: Improve test coverage of test_maps
>   samples/bpf: Reduce syscall overhead in map_perf_test.
>   bpf: Relax the requirement to use preallocated hash maps in tracing
>     progs.
> 
>  include/linux/bpf_mem_alloc.h           |  26 ++
>  kernel/bpf/Makefile                     |   2 +-
>  kernel/bpf/hashtab.c                    |  16 +-
>  kernel/bpf/memalloc.c                   | 512 ++++++++++++++++++++++++
>  kernel/bpf/verifier.c                   |  31 +-
>  samples/bpf/map_perf_test_kern.c        |  22 +-
>  tools/testing/selftests/bpf/test_maps.c |  38 +-
>  7 files changed, 610 insertions(+), 37 deletions(-)
>  create mode 100644 include/linux/bpf_mem_alloc.h
>  create mode 100644 kernel/bpf/memalloc.c
> 
> -- 
> 2.30.2
> 
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