On 11/24/25 19:06, Josh Poimboeuf wrote:
On Mon, Nov 24, 2025 at 05:54:15PM -0500, Andrey Grodzovsky wrote:
On 11/24/25 17:51, Josh Poimboeuf wrote:
On Mon, Nov 24, 2025 at 05:06:04PM -0500, Andrey Grodzovsky wrote:
Andrey, can you try this patch?
Hey Josh, thank you for looking, can you please advise the stable
kernel version you have made this changes on top off so I can cleanly
apply ? Alternatively just provide git commit sha in Linus
tree I can reset my branch to.
I will happily test this as soon as I can and report back.
It's based on Linus's tree.
Latest more or less ?
Yes, it still applies to his latest master (v6.18-rc7).
Tested, looks good.
kernel as above, before patch application dmesg
ubuntu-24-04@ubuntu-24-04:~/livepatch-bpf-test$ sudo insmod
livepatches/livepatch_cmdline_test.ko
ubuntu-24-04@ubuntu-24-04:~/livepatch-bpf-test$ sudo dmesg -w
[ 128.434944] livepatch_cmdline_test: loading out-of-tree module taints
kernel.
[ 128.434955] livepatch_cmdline_test: tainting kernel with TAINT_LIVEPATCH
[ 128.434958] livepatch_cmdline_test: module verification failed:
signature and/or required key missing - tainting kernel
[ 128.435579] livepatch_cmdline_test: initializing
[ 128.435640] livepatch: enabling patch 'livepatch_cmdline_test'
[ 128.435643] livepatch: 'livepatch_cmdline_test': initializing
patching transition
[ 128.439051] livepatch: 'livepatch_cmdline_test': starting patching
transition
[ 128.439982] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 128.440028] livepatch: klp_try_switch_task: swapper/0:0 is running
[ 128.440041] livepatch: klp_try_switch_task: swapper/1:0 is running
[ 128.440051] livepatch: klp_try_switch_task: swapper/3:0 is running
[ 128.440060] livepatch: klp_try_switch_task: swapper/4:0 is running
[ 128.440069] livepatch: klp_try_switch_task: swapper/5:0 is running
[ 128.440078] livepatch: klp_try_switch_task: swapper/6:0 is running
[ 128.440090] livepatch: klp_try_switch_task: swapper/7:0 is running
[ 128.440099] livepatch: klp_try_switch_task: swapper/8:0 is running
[ 128.440125] livepatch: klp_try_switch_task: swapper/9:0 is running
[ 128.440138] livepatch: klp_try_switch_task: swapper/12:0 is running
[ 128.440147] livepatch: klp_try_switch_task: swapper/13:0 is running
[ 128.440161] livepatch_cmdline_test: patch enabled successfully
[ 129.586202] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 130.651011] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 131.595098] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 132.910147] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 134.578055] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 135.613832] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 136.646585] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 137.589959] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 138.607729] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 139.570125] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 140.601715] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 141.643745] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 142.595307] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 143.605116] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 144.628517] livepatch: klp_try_switch_task: tcp_recv_hang:1219 has an
unreliable stack
[ 144.628544] livepatch: signaling remaining tasks
[ 145.611813] livepatch: 'livepatch_cmdline_test': completing patching
transition
[ 145.612271] livepatch: 'livepatch_cmdline_test': patching complete
After patch application -
ubuntu-24-04@ubuntu-24-04:~$ sudo insmod
livepatches/livepatc^Ccmdline_test.ko
ubuntu-24-04@ubuntu-24-04:~$ cd livepatch-bpf-test/
ubuntu-24-04@ubuntu-24-04:~/livepatch-bpf-test$ sudo insmod
livepatches/livepatch_cmdline_test.ko
ubuntu-24-04@ubuntu-24-04:~/livepatch-bpf-test$ sudo dmesg -dw
[ 270.168371 < 0.000000>] livepatch_cmdline_test: loading
out-of-tree module taints kernel.
[ 270.168386 < 0.000015>] livepatch_cmdline_test: tainting kernel
with TAINT_LIVEPATCH
[ 270.168389 < 0.000003>] livepatch_cmdline_test: module
verification failed: signature and/or required key missing - tainting kernel
[ 270.169202 < 0.000813>] livepatch_cmdline_test: initializing
[ 270.169260 < 0.000058>] livepatch: enabling patch
'livepatch_cmdline_test'
[ 270.169262 < 0.000002>] livepatch: 'livepatch_cmdline_test':
initializing patching transition
[ 270.171969 < 0.002707>] livepatch: 'livepatch_cmdline_test':
starting patching transition
[ 270.172892 < 0.000923>] livepatch: klp_try_switch_task:
swapper/0:0 is running
[ 270.172904 < 0.000012>] livepatch: klp_try_switch_task:
swapper/2:0 is running
[ 270.172912 < 0.000008>] livepatch: klp_try_switch_task:
swapper/4:0 is running
[ 270.172920 < 0.000008>] livepatch: klp_try_switch_task:
swapper/5:0 is running
[ 270.172927 < 0.000007>] livepatch: klp_try_switch_task:
swapper/7:0 is running
[ 270.172935 < 0.000008>] livepatch: klp_try_switch_task:
swapper/8:0 is running
[ 270.172942 < 0.000007>] livepatch: klp_try_switch_task:
swapper/9:0 is running
[ 270.172954 < 0.000012>] livepatch: klp_try_switch_task:
swapper/10:0 is running
[ 270.172959 < 0.000005>] livepatch: klp_try_switch_task:
swapper/11:0 is running
[ 270.172966 < 0.000007>] livepatch: klp_try_switch_task:
swapper/13:0 is running
[ 270.172971 < 0.000005>] livepatch_cmdline_test: patch enabled
successfully
[ 271.008394 < 0.835423>] livepatch: 'livepatch_cmdline_test':
completing patching transition
[ 271.009156 < 0.000762>] livepatch: 'livepatch_cmdline_test':
patching complete
ubuntu-24-04@ubuntu-24-04:~/livepatch-bpf-test$ sudo cat /proc/kallsyms
| grep cmdline_proc_show
ffffffffb4a55c20 t __pfx_cmdline_proc_show
ffffffffb4a55c30 t cmdline_proc_show
ffffffffc09300b0 t livepatch_cmdline_proc_show [livepatch_cmdline_test]
ffffffffc09300a0 t __pfx_livepatch_cmdline_proc_show
[livepatch_cmdline_test]
ubuntu-24-04@ubuntu-24-04:~/livepatch-bpf-test$
Andrey
