summaryrefslogtreecommitdiff
path: root/tools/bpf/bpftool/prog.c
diff options
context:
space:
mode:
authorQuentin Monnet <quentin@isovalent.com>2022-06-10 12:26:47 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2022-06-14 22:18:06 +0200
commit6b4384ff108874cf336fe2fb1633313c2c7620bf (patch)
tree8a61fe1fc670563a4429fc935721eeeeaa812ff7 /tools/bpf/bpftool/prog.c
parentfc386ba7211d514f2c20285cb6b9b502618634e0 (diff)
Revert "bpftool: Use libbpf 1.0 API mode instead of RLIMIT_MEMLOCK"
This reverts commit a777e18f1bcd32528ff5dfd10a6629b655b05eb8. In commit a777e18f1bcd ("bpftool: Use libbpf 1.0 API mode instead of RLIMIT_MEMLOCK"), we removed the rlimit bump in bpftool, because the kernel has switched to memcg-based memory accounting. Thanks to the LIBBPF_STRICT_AUTO_RLIMIT_MEMLOCK, we attempted to keep compatibility with other systems and ask libbpf to raise the limit for us if necessary. How do we know if memcg-based accounting is supported? There is a probe in libbpf to check this. But this probe currently relies on the availability of a given BPF helper, bpf_ktime_get_coarse_ns(), which landed in the same kernel version as the memory accounting change. This works in the generic case, but it may fail, for example, if the helper function has been backported to an older kernel. This has been observed for Google Cloud's Container-Optimized OS (COS), where the helper is available but rlimit is still in use. The probe succeeds, the rlimit is not raised, and probing features with bpftool, for example, fails. A patch was submitted [0] to update this probe in libbpf, based on what the cilium/ebpf Go library does [1]. It would lower the soft rlimit to 0, attempt to load a BPF object, and reset the rlimit. But it may induce some hard-to-debug flakiness if another process starts, or the current application is killed, while the rlimit is reduced, and the approach was discarded. As a workaround to ensure that the rlimit bump does not depend on the availability of a given helper, we restore the unconditional rlimit bump in bpftool for now. [0] https://lore.kernel.org/bpf/20220609143614.97837-1-quentin@isovalent.com/ [1] https://github.com/cilium/ebpf/blob/v0.9.0/rlimit/rlimit.go#L39 Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Yafang Shao <laoar.shao@gmail.com> Cc: Stanislav Fomichev <sdf@google.com> Link: https://lore.kernel.org/bpf/20220610112648.29695-2-quentin@isovalent.com
Diffstat (limited to 'tools/bpf/bpftool/prog.c')
-rw-r--r--tools/bpf/bpftool/prog.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index e71f0b2da50b..f081de398b60 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1590,6 +1590,8 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
}
}
+ set_max_rlimit();
+
if (verifier_logs)
/* log_level1 + log_level2 + stats, but not stable UAPI */
open_opts.kernel_log_level = 1 + 2 + 4;
@@ -2287,6 +2289,7 @@ static int do_profile(int argc, char **argv)
}
}
+ set_max_rlimit();
err = profiler_bpf__load(profile_obj);
if (err) {
p_err("failed to load profile_obj");