From: Hui Zhu <[email protected]> Add a sample eBPF program demonstrating the new memory controller eBPF support. This example serves as both a reference implementation and a validation tool for the memcg eBPF functionality.
The sample includes: - memcg_printk.bpf.c: An eBPF program that attaches to the try_charge_memcg hook and prints detailed information about memory charging events, including: * Memory cgroup name * GFP flags and page count * Reclamation options * Affected memory cgroup (when applicable) - memcg_printk.c: A userspace loader program that: * Loads the eBPF object file * Finds and attaches the memcg_ops struct ops * Keeps the program attached until interrupted * Provides proper error handling and cleanup Usage: $ ./samples/bpf/memcg_printk This will attach the eBPF program to the memcg charging path. Output can be viewed via kernel trace events (e.g., trace_printk logs). The program demonstrates: - Accessing memory cgroup context fields - Using bpf_printk for debugging and monitoring - Proper struct ops registration via libbpf - Integration with the kernel's BPF infrastructure Signed-off-by: Geliang Tang <[email protected]> Signed-off-by: Hui Zhu <[email protected]> --- MAINTAINERS | 2 + samples/bpf/Makefile | 2 + samples/bpf/memcg_printk.bpf.c | 30 +++++++++++++ samples/bpf/memcg_printk.c | 82 ++++++++++++++++++++++++++++++++++ 4 files changed, 116 insertions(+) create mode 100644 samples/bpf/memcg_printk.bpf.c create mode 100644 samples/bpf/memcg_printk.c diff --git a/MAINTAINERS b/MAINTAINERS index dc3aa53d2346..c8f32f7dad3f 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6356,6 +6356,8 @@ F: mm/memcontrol_bpf.h F: mm/page_counter.c F: mm/swap_cgroup.c F: samples/cgroup/* +F: samples/memcg_printk.bpf.c +F: samples/memcg_printk.c F: tools/testing/selftests/bpf/*/memcg_ops.c F: tools/testing/selftests/cgroup/memcg_protection.m F: tools/testing/selftests/cgroup/test_hugetlb_memcg.c diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 95a4fa1f1e44..d50e958fc8d5 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -37,6 +37,7 @@ tprogs-y += xdp_fwd tprogs-y += task_fd_query tprogs-y += ibumad tprogs-y += hbm +tprogs-y += memcg_printk # Libbpf dependencies LIBBPF_SRC = $(TOOLS_PATH)/lib/bpf @@ -122,6 +123,7 @@ always-y += task_fd_query_kern.o always-y += ibumad_kern.o always-y += hbm_out_kern.o always-y += hbm_edt_kern.o +always-y += memcg_printk.bpf.o COMMON_CFLAGS = $(TPROGS_USER_CFLAGS) TPROGS_LDFLAGS = $(TPROGS_USER_LDFLAGS) diff --git a/samples/bpf/memcg_printk.bpf.c b/samples/bpf/memcg_printk.bpf.c new file mode 100644 index 000000000000..66c87bf4cbcb --- /dev/null +++ b/samples/bpf/memcg_printk.bpf.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "vmlinux.h" + +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +SEC("struct_ops/try_charge_memcg") +int BPF_PROG(handle_try_charge_memcg, struct try_charge_memcg *tcm) +{ + bpf_printk( + "memcg %s gfp_mask 0x%x nr_pages %lu reclaim_options 0x%lx\n", + tcm->memcg->css.cgroup->kn->name, + tcm->gfp_mask, + tcm->nr_pages, + tcm->reclaim_options); + if (!tcm->charge_done) + bpf_printk("memcg %s mem_over_limit %s\n", + tcm->memcg->css.cgroup->kn->name, + tcm->mem_over_limit->css.cgroup->kn->name); + + return 0; +} + +SEC(".struct_ops") +struct memcg_ops mcg_ops = { + .try_charge_memcg = (void *)handle_try_charge_memcg, +}; + +char _license[] SEC("license") = "GPL"; diff --git a/samples/bpf/memcg_printk.c b/samples/bpf/memcg_printk.c new file mode 100644 index 000000000000..a2c5be2415ea --- /dev/null +++ b/samples/bpf/memcg_printk.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define _GNU_SOURCE + +#include <errno.h> +#include <signal.h> +#include <bpf/libbpf.h> + +static bool exiting; + +static void sig_handler(int sig) +{ + exiting = true; +} + +static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args) +{ + return vfprintf(stderr, format, args); +} + +int main(int argc, char **argv) +{ + struct bpf_object *obj = NULL; + struct bpf_link *link = NULL; + struct bpf_map *map; + char filename[256]; + int err; + + exiting = false; + + signal(SIGINT, sig_handler); + signal(SIGTERM, sig_handler); + + libbpf_set_print(libbpf_print_fn); + + snprintf(filename, sizeof(filename), "%s.bpf.o", argv[0]); + obj = bpf_object__open_file(filename, NULL); + err = libbpf_get_error(obj); + if (err) { + fprintf(stderr, "Failed to open BPF object file: %d\n", + err); + obj = NULL; + goto cleanup; + } + + err = bpf_object__load(obj); + if (err) { + fprintf(stderr, "Failed to loading BPF object file: %d\n", + err); + goto cleanup; + } + + map = bpf_object__find_map_by_name(obj, "mcg_ops"); + if (!map) { + fprintf(stderr, "Failed to find struct_ops map 'mcg_ops'\n"); + err = -ENOENT; + goto cleanup; + } + + link = bpf_map__attach_struct_ops(map); + err = libbpf_get_error(link); + if (err) { + fprintf(stderr, "Failed to attach struct ops: %d\n", + err); + link = NULL; + goto cleanup; + } + + printf("Press Ctrl+C to exit...\n"); + + while (!exiting) + sleep(1); + + printf("Bye!\n"); + +cleanup: + if (link) + bpf_link__destroy(link); + if (obj) + bpf_object__close(obj); + + return err; +} -- 2.43.0
