[PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory · Jay Wang <hidden> · 2026-10-01
[PATCH bpf-next v4 01/12] bpf: pass the vmlinux BTF to btf_parse_module() and let it adopt the data · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 01/12] bpf: pass the vmlinux BTF to btf_parse_module() and let it adopt the data · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 02/12] bpf: split the kfunc, dtor kfunc and struct_ops registration bodies · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 02/12] bpf: split the kfunc, dtor kfunc and struct_ops registration bodies · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 03/12] bpf: fetch the vmlinux BTF where kernel types enter a program · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 03/12] bpf: fetch the vmlinux BTF where kernel types enter a program · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 04/12] bpf: take the vmlinux BTF from the btf_vmlinux module · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 04/12] bpf: take the vmlinux BTF from the btf_vmlinux module · bot+bpf-ci@kernel.org · 2026-10-01
Re: [PATCH bpf-next v4 04/12] bpf: take the vmlinux BTF from the btf_vmlinux module · sashiko-bot@kernel.org · 2026-10-02
Re: [PATCH bpf-next v4 04/12] bpf: take the vmlinux BTF from the btf_vmlinux module · Alexei Starovoitov <hidden> · 2026-10-02
[PATCH bpf-next v4 05/12] bpf, tracing: load the vmlinux BTF where tracefs and bpffs requests start · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 05/12] bpf, tracing: load the vmlinux BTF where tracefs and bpffs requests start · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 06/12] bpf: defer vmlinux kfunc and struct_ops registrations · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 06/12] bpf: defer vmlinux kfunc and struct_ops registrations · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 07/12] bpf: keep module BTF until the vmlinux BTF is available · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 07/12] bpf: keep module BTF until the vmlinux BTF is available · bot+bpf-ci@kernel.org · 2026-10-01
Re: [PATCH bpf-next v4 07/12] bpf: keep module BTF until the vmlinux BTF is available · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 08/12] bpf: expose deferred .BTF.base module BTF in sysfs from module load · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 08/12] bpf: expose deferred .BTF.base module BTF in sysfs from module load · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 09/12] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 09/12] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 10/12] resolve_btfids: add --btf_link to fill in .BTF.link records · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 10/12] resolve_btfids: add --btf_link to fill in .BTF.link records · bot+bpf-ci@kernel.org · 2026-10-01
Re: [PATCH bpf-next v4 10/12] resolve_btfids: add --btf_link to fill in .BTF.link records · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 11/12] tools, samples: take the vmlinux BTF from vmlinux.unstripped first · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 11/12] tools, samples: take the vmlinux BTF from vmlinux.unstripped first · sashiko-bot@kernel.org · 2026-10-02
[PATCH bpf-next v4 12/12] kbuild, bpf: allow building the vmlinux BTF as a module · Jay Wang <hidden> · 2026-10-01
Re: [PATCH bpf-next v4 12/12] kbuild, bpf: allow building the vmlinux BTF as a module · sashiko-bot@kernel.org · 2026-10-02
Re: [PATCH bpf-next v4 12/12] kbuild, bpf: allow building the vmlinux BTF as a module · Alan Maguire <hidden> · 2026-10-02
Re: [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory · Ihor Solodrai <ihor.solodrai@linux.dev> · 2026-10-02
Re: [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory · Jay Wang <hidden> · 2026-10-02
Re: [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory · Alan Maguire <hidden> · 2026-10-02
Re: [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory · Ihor Solodrai <ihor.solodrai@linux.dev> · 2026-10-02
Re: [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory · Alexei Starovoitov <hidden> · 2026-10-03
Re: [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory · Alan Maguire <hidden> · 2026-10-03
Re: [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory · Alexei Starovoitov <hidden> · 2026-10-03

Re: [PATCH bpf-next v4 08/12] bpf: expose deferred .BTF.base module BTF in sysfs from module load

From: sashiko-bot@kernel.org
Date: 2026-10-02 09:14:19
Also in: bpf, linux-input, linux-perf-users, linux-trace-kernel, sched-ext

A module with a .BTF.base section (built out of tree) that is loaded
before the vmlinux BTF only gets its /sys/kernel/btf file once the
vmlinux BTF has been loaded and its BTF relocated, because the raw .BTF
is only valid against the distilled base and relocation rewrites it in
place.  Until then the module is missing from /sys/kernel/btf, unlike
with =y, and reading its file cannot trigger the load.

Create the file at module load instead, with its final size: relocation
only rewrites type ids and string offsets, never the length.  Its reader,
btf_module_sysfs_read_deferred(), has the vmlinux BTF loaded, which parses
and relocates the kept modules, then waits until this module's BTF is
published (btf_mod->ready) before serving it, so no unrelocated or
half-relocated data is ever visible.  If the module goes away or its BTF
turns out unusable first (btf_mod->gone), or the vmlinux BTF cannot be
loaded, the read fails with -ENODEV.
[ ... ]

Modules without .BTF.base are unchanged: their data is final and is
served as is.

Signed-off-by: Jay Wang <redacted>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261001225214.12351-1-wanjay@amazon.com?part=8

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