From: Jay Wang <wanjay@amazon.com>
To: <sashiko-bot@kernel.org>
Cc: <bpf@vger.kernel.org>, <linux-modules@vger.kernel.org>
Subject: Re: [PATCH bpf-next v2 6/9] bpf: keep module BTF until the vmlinux BTF is available
Date: Fri, 25 Sep 2026 23:02:51 +0000 [thread overview]
Message-ID: <20260925230251.34380-1-wanjay@amazon.com> (raw)
In-Reply-To: <20260925212938.3B4D91F000FF@smtp.kernel.org>
No change for this in v3:
https://lore.kernel.org/bpf/20260925224229.1850-1-wanjay@amazon.com/
I don't think this can happen. do_init_module() runs the
MODULE_STATE_LIVE notifier chain before it drops the reference it holds
during initialization: the "Drop initial reference." module_put() comes
after the notifiers, under module_mutex. While the LIVE notifier runs,
the refcount is therefore above MODULE_REF_BASE, and a concurrent
delete_module() fails in try_stop_module() with -EWOULDBLOCK (short of
a forced unload, which is unsafe for any user of the module). So the
module and its kfunc sets and struct_ops stay valid for the whole of
btf_apply_deferred_regs() here, without a try_module_get().
Jay
next prev parent reply other threads:[~2026-09-25 23:02 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-25 21:13 [PATCH bpf-next v2 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 21:13 ` [PATCH bpf-next v2 1/9] bpf: pass the vmlinux BTF to btf_parse_module() and let it adopt the data Jay Wang
2026-09-25 21:13 ` [PATCH bpf-next v2 2/9] bpf: split the kfunc, dtor kfunc and struct_ops registration bodies Jay Wang
2026-09-25 21:13 ` [PATCH bpf-next v2 3/9] bpf: fetch the vmlinux BTF where kernel types enter a program Jay Wang
2026-09-25 21:42 ` sashiko-bot
2026-09-25 23:02 ` Jay Wang
2026-09-25 21:13 ` [PATCH bpf-next v2 4/9] bpf: take the vmlinux BTF from the btf_vmlinux module Jay Wang
2026-09-25 21:13 ` [PATCH bpf-next v2 5/9] bpf: defer vmlinux kfunc and struct_ops registrations Jay Wang
2026-09-25 21:13 ` [PATCH bpf-next v2 6/9] bpf: keep module BTF until the vmlinux BTF is available Jay Wang
2026-09-25 21:29 ` sashiko-bot
2026-09-25 23:02 ` Jay Wang [this message]
2026-09-25 21:13 ` [PATCH bpf-next v2 7/9] bpf: expose deferred .BTF.base module BTF in sysfs from module load Jay Wang
2026-09-25 21:13 ` [PATCH bpf-next v2 8/9] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate Jay Wang
2026-09-25 21:13 ` [PATCH bpf-next v2 9/9] kbuild, bpf: allow building the vmlinux BTF as a module Jay Wang
2026-09-25 21:33 ` sashiko-bot
2026-09-25 23:02 ` Jay Wang
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