From: Vivek Goyal <vgoyal@xxxxxxxxxx>
Subject: kexec: migrate to reboot cpu
Commit 1b3a5d02ee0 ("reboot: move arch/x86 reboot= handling to generic
kernel") moved reboot= handling to generic code. In the process it also
removed the code in native_machine_shutdown() which are moving reboot
process to reboot_cpu/cpu0.
I guess that thought must have been that all reboot paths are calling
migrate_to_reboot_cpu(), so we don't need this special handling. But
kexec reboot path (kernel_kexec()) is not calling migrate_to_reboot_cpu()
so above change broke kexec. Now reboot can happen on non-boot cpu and
when INIT is sent in second kerneo to bring up BP, it brings down the
machine.
So start calling migrate_to_reboot_cpu() in kexec reboot path to avoid
this problem.
Bisected by WANG Chao.
Reported-by: Matthew Whitehead <mwhitehe@xxxxxxxxxx>
Reported-by: Dave Young <dyoung@xxxxxxxxxx>
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Tested-by: Baoquan He <bhe@xxxxxxxxxx>
Tested-by: WANG Chao <chaowang@xxxxxxxxxx>
Acked-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/reboot.h | 1 +
kernel/kexec.c | 1 +
kernel/reboot.c | 2 +-
3 files changed, 3 insertions(+), 1 deletion(-)
diff -puN include/linux/reboot.h~kexec-migrate-to-reboot-cpu include/linux/reboot.h
--- a/include/linux/reboot.h~kexec-migrate-to-reboot-cpu
+++ a/include/linux/reboot.h
@@ -43,6 +43,7 @@ extern int unregister_reboot_notifier(st
* Architecture-specific implementations of sys_reboot commands.
*/
+extern void migrate_to_reboot_cpu(void);
extern void machine_restart(char *cmd);
extern void machine_halt(void);
extern void machine_power_off(void);
diff -puN kernel/kexec.c~kexec-migrate-to-reboot-cpu kernel/kexec.c
--- a/kernel/kexec.c~kexec-migrate-to-reboot-cpu
+++ a/kernel/kexec.c
@@ -1680,6 +1680,7 @@ int kernel_kexec(void)
{
kexec_in_progress = true;
kernel_restart_prepare(NULL);
+ migrate_to_reboot_cpu();
printk(KERN_EMERG "Starting new kernel\n");
machine_shutdown();
}
diff -puN kernel/reboot.c~kexec-migrate-to-reboot-cpu kernel/reboot.c
--- a/kernel/reboot.c~kexec-migrate-to-reboot-cpu
+++ a/kernel/reboot.c
@@ -104,7 +104,7 @@ int unregister_reboot_notifier(struct no
}
EXPORT_SYMBOL(unregister_reboot_notifier);
-static void migrate_to_reboot_cpu(void)
+void migrate_to_reboot_cpu(void)
{
/* The boot cpu is always logical cpu 0 */
int cpu = reboot_cpu;
_
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