From: Jay Wang <wanjay@amazon.com>
To: <bot+bpf-ci@kernel.org>, <bpf@vger.kernel.org>, <ast@kernel.org>,
<daniel@iogearbox.net>, <andrii@kernel.org>, <eddyz87@gmail.com>,
<memxor@gmail.com>
Cc: <alan.maguire@oracle.com>, <martin.lau@linux.dev>,
<yonghong.song@linux.dev>, <jolsa@kernel.org>,
<nathan@kernel.org>, <nsc@kernel.org>,
<linux-kbuild@vger.kernel.org>, <mcgrof@kernel.org>,
<petr.pavlu@suse.com>, <samitolvanen@google.com>,
<linux-modules@vger.kernel.org>, <ojeda@kernel.org>,
<rust-for-linux@vger.kernel.org>, <arnd@arndb.de>,
<linux-kernel@vger.kernel.org>, <abuehaze@amazon.com>,
<doebel@amazon.de>, <mpohlack@amazon.de>,
<jay.wang.upstream@gmail.com>, <martin.lau@kernel.org>,
<mason@kernel.org>, <ihor.solodrai@linux.dev>,
<rostedt@goodmis.org>, <mhiramat@kernel.org>,
<linux-trace-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next v3 7/9] bpf: expose deferred .BTF.base module BTF in sysfs from module load
Date: Thu, 1 Oct 2026 23:52:45 +0000 [thread overview]
Message-ID: <20261001235245.6625-1-wanjay@amazon.com> (raw)
In-Reply-To: <3541dcaa6eba351d0e66f2c324b2919453a7ad4f1a29170d8ce9b4435feeb0d8@mail.kernel.org>
Right, fixed in v4 (patch 8/12):
https://lore.kernel.org/bpf/20261001225214.12351-1-wanjay@amazon.com/
The reader no longer loads the vmlinux BTF itself. If it is not there
yet, the reader queues a work item that calls bpf_load_btf_vmlinux(),
and waits for the module's BTF to be published, for @gone, or for the
load attempt to end without the BTF. MODULE_STATE_GOING sets @gone and
wakes before it removes the file, so the drain no longer waits on a
module load: in your cycle the reader returns -ENODEV, the drain
completes, GOING returns, and the kworker's modprobe gets the rwsem once
the writer is done.
On the lock comment, you are right that the btf_module_mutex ->
cand_cache_mutex edge is gone. v4 states what the separate lock does
keep: btf_module_mutex, which the module notifier takes, is never taken
under btf_vmlinux_lock.
Jay
next prev parent reply other threads:[~2026-10-01 23:52 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-25 22:42 [PATCH bpf-next v3 0/9] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory Jay Wang
2026-09-25 22:42 ` [PATCH bpf-next v3 1/9] bpf: pass the vmlinux BTF to btf_parse_module() and let it adopt the data Jay Wang
2026-09-25 22:42 ` [PATCH bpf-next v3 2/9] bpf: split the kfunc, dtor kfunc and struct_ops registration bodies Jay Wang
2026-09-25 22:42 ` [PATCH bpf-next v3 3/9] bpf: fetch the vmlinux BTF where kernel types enter a program Jay Wang
2026-09-25 22:42 ` [PATCH bpf-next v3 4/9] bpf: take the vmlinux BTF from the btf_vmlinux module Jay Wang
2026-09-25 23:23 ` bot+bpf-ci
2026-10-01 23:51 ` Jay Wang
2026-09-26 8:29 ` Alexei Starovoitov
2026-10-01 23:51 ` Jay Wang
2026-09-25 22:42 ` [PATCH bpf-next v3 5/9] bpf: defer vmlinux kfunc and struct_ops registrations Jay Wang
2026-09-25 23:34 ` bot+bpf-ci
2026-10-01 23:52 ` Jay Wang
2026-09-25 22:42 ` [PATCH bpf-next v3 6/9] bpf: keep module BTF until the vmlinux BTF is available Jay Wang
2026-09-25 22:42 ` [PATCH bpf-next v3 7/9] bpf: expose deferred .BTF.base module BTF in sysfs from module load Jay Wang
2026-09-25 23:23 ` bot+bpf-ci
2026-10-01 23:52 ` Jay Wang [this message]
2026-09-25 22:42 ` [PATCH bpf-next v3 8/9] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate Jay Wang
2026-09-25 23:23 ` bot+bpf-ci
2026-10-01 23:53 ` Jay Wang
2026-09-25 22:42 ` [PATCH bpf-next v3 9/9] kbuild, bpf: allow building the vmlinux BTF as a module Jay Wang
2026-09-25 23:34 ` bot+bpf-ci
2026-10-01 23:53 ` Jay Wang
2026-09-28 10:00 ` Alan Maguire
[not found] ` <DM6PR18MB2666F6B235D5B356AA157A7DA98D2@DM6PR18MB2666.namprd18.prod.outlook.com>
2026-09-29 18:25 ` Alan Maguire
2026-10-01 23:53 ` Jay Wang
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