Commit c97102ba authored Dec 18, 2013 by Vivek Goyal Committed by Linus Torvalds Dec 18, 2013

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: Matthew Whitehead <mwhitehe@redhat.com>
Reported-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Tested-by: Baoquan He <bhe@redhat.com>
Tested-by: WANG Chao <chaowang@redhat.com>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus 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;

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