From patchwork Wed Sep 25 22:30:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 13812492 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1F57A13D891; Wed, 25 Sep 2024 22:30:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727303425; cv=none; b=cxrVOCQG6Xmc1vtrAkiNW5537Tu1uMYisx3+5Bz3+tuUiGP2TUnZUzCI7vHY29G8sfB8ppzECpOANtB779/g9X9ZAupupsywsu+uAFgXvzIg7t6zuqjIrNRf9pGaO1smYPfdkaP140IPz970z8EsCzn7kJlzb+yqImRlhFOWfms= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727303425; c=relaxed/simple; bh=/wpNuyYlQgTLd8to7yv58RW9K/fnJNPPR7Yi9IPGjww=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=twUTCMNbDadO3Ej2mWIZVfeWFG5snw9iF87zzqm3wCV/azjwte7Wgc1WJ8fGNboqE+JUT+uEhlo1A9b897f1e0aLjSD0sf8DO1n5Sq9pSXnFW5jKd5qHVxaTDso8uMTIa1Z9ZvUvH7FpeidFqpYaXplXc/OiTIrIlQm1MLLu6zA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Nog7Mu8r; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Nog7Mu8r" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF73CC4CEC3; Wed, 25 Sep 2024 22:30:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727303424; bh=/wpNuyYlQgTLd8to7yv58RW9K/fnJNPPR7Yi9IPGjww=; h=From:To:Cc:Subject:Date:From; b=Nog7Mu8ryCZIbKiU+7l2FP2MewyEIKi52moHSJyUsIYX3gegdE3ejjnLfaq5M0o/b a6deA05wMrLbyO0tzRI82+imB0c5GsmMLOvgsVwTiuHyrAC3K4i8XgZrY0qFBFCh2A l7dwnt91wtbhHEinc9g9ObRIRZpZrQxJiDqwhaKE0Z//BwFYEmwdf+sN3mRnsXDwDL 8JpdKFXAq41biEuyplUCfv27kj6yZ6zSg56wxIFKxNIRbeJAMzV4pSHFQdjfz+H67s fRCcXQjwTn7KsM+dF00n2Hh+TmUxzVH7IykxOgE3lf21yWDlIiNm07GijRmr87+kbz k09AM+jhu3u5A== From: Namhyung Kim To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , LKML , bpf@vger.kernel.org, Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org Subject: [RFC/PATCH bpf-next 0/3] bpf: Add slab iterator and kfunc (v1) Date: Wed, 25 Sep 2024 15:30:20 -0700 Message-ID: <20240925223023.735947-1-namhyung@kernel.org> X-Mailer: git-send-email 2.46.0.792.g87dc391469-goog Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net X-Patchwork-State: RFC Hello, I'm proposing a new iterator and a kfunc for the slab memory allocator to get information of each kmem_cache like in /proc/slabinfo or /sys/kernel/slab. Maybe I need to call it kmem_cache iter but slab was short and easier to call. :) My use case is `perf lock contention` tool which shows contended locks but many of them are not global locks and don't have symbols. If it can tranlate the address of the lock in a slab object to the name of the slab, it'd be much more useful. I'm not aware of type information in slab yet, but I was told there's a work to associate BTF ID with it. It'd be definitely helpful to my use case. Probably we need another kfunc to get the start address of the object or the offset in the object from an address if the type info is available. But I want to start with a simple thing first. The slab_iter iterates kmem_cache objects under slab_mutex and will be useful for userspace to prepare some work for specific slabs like setting up filters in advance. And the bpf_get_slab_cache() kfunc will return a pointer to a slab from the address of a lock. And the test code is to read from the iterator and make sure it finds a slab cache of the task_struct for the current task. The code is available at 'bpf/slab-iter-v1' branch in https://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git Thanks, Namhyung Namhyung Kim (3): bpf: Add slab iterator mm/bpf: Add bpf_get_slab_cache() kfunc selftests/bpf: Add a test for slab_iter include/linux/btf_ids.h | 1 + kernel/bpf/Makefile | 1 + kernel/bpf/helpers.c | 1 + kernel/bpf/slab_iter.c | 131 ++++++++++++++++++ mm/slab_common.c | 14 ++ .../selftests/bpf/prog_tests/slab_iter.c | 64 +++++++++ tools/testing/selftests/bpf/progs/bpf_iter.h | 7 + tools/testing/selftests/bpf/progs/slab_iter.c | 62 +++++++++ 8 files changed, 281 insertions(+) create mode 100644 kernel/bpf/slab_iter.c create mode 100644 tools/testing/selftests/bpf/prog_tests/slab_iter.c create mode 100644 tools/testing/selftests/bpf/progs/slab_iter.c Acked-by: Roman Gushchin (mm/*) Acked-by: Vlastimil Babka #mm/slab