The patch titled
Subject: panic: call panic handlers before panic_other_cpus_shutdown()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
panic-call-panic-handlers-before-panic_other_cpus_shutdown.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/panic-call-panic-handlers-before-panic_other_cpus_shutdown.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Hamza Mahfooz <hamzamahfooz@xxxxxxxxxxxxxxxxxxx>
Subject: panic: call panic handlers before panic_other_cpus_shutdown()
Date: Fri, 21 Feb 2025 16:30:52 -0500
Since the panic handlers may require certain cpus to be online to panic
gracefully, we should call them before turning off SMP. Without this
re-ordering, on Hyper-V hv_panic_vmbus_unload() times out, because the
vmbus channel is bound to VMBUS_CONNECT_CPU and unless the crashing cpu is
the same as VMBUS_CONNECT_CPU, VMBUS_CONNECT_CPU will be offlined by
crash_smp_send_stop() before the vmbus channel can be deconstructed.
Link: https://lkml.kernel.org/r/20250221213055.133849-1-hamzamahfooz@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Hamza Mahfooz <hamzamahfooz@xxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Baoquan he <bhe@xxxxxxxxxx>
Cc: Dexuan Cui <decui@xxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: Hamza Mahfooz <hamzamahfooz@xxxxxxxxxxxxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Ryo Takakura <takakura@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/panic.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/panic.c~panic-call-panic-handlers-before-panic_other_cpus_shutdown
+++ a/kernel/panic.c
@@ -372,16 +372,16 @@ void panic(const char *fmt, ...)
if (!_crash_kexec_post_notifiers)
__crash_kexec(NULL);
- panic_other_cpus_shutdown(_crash_kexec_post_notifiers);
-
- printk_legacy_allow_panic_sync();
-
/*
* Run any panic handlers, including those that might need to
* add information to the kmsg dump output.
*/
atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
+ panic_other_cpus_shutdown(_crash_kexec_post_notifiers);
+
+ printk_legacy_allow_panic_sync();
+
panic_print_sys_info(false);
kmsg_dump_desc(KMSG_DUMP_PANIC, buf);
_
Patches currently in -mm which might be from hamzamahfooz@xxxxxxxxxxxxxxxxxxx are
panic-call-panic-handlers-before-panic_other_cpus_shutdown.patch
