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Commit c97102ba authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
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kexec: migrate to reboot cpu 



Commit 1b3a5d02 ("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: default avatarMatthew Whitehead <mwhitehe@redhat.com>
Reported-by: default avatarDave Young <dyoung@redhat.com>
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Tested-by: default avatarBaoquan He <bhe@redhat.com>
Tested-by: default avatarWANG Chao <chaowang@redhat.com>
Acked-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b0031f22

include/linux/reboot.h

+1 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ extern int unregister_reboot_notifier(struct notifier_block *); 
 * 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);

kernel/kexec.c

+1 −0
Original line number Diff line number Diff line
@@ -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();

	}

kernel/reboot.c

+1 −1
Original line number Diff line number Diff line
@@ -104,7 +104,7 @@ int unregister_reboot_notifier(struct notifier_block *nb) 
}

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;