Commit d57d6fe5 authored by Stephen Brennan's avatar Stephen Brennan Committed by Wei Liu
Browse files

drivers: hv: log when enabling crash_kexec_post_notifiers 



Recently I went down a rabbit hole looking at a race condition in
panic() on a Hyper-V guest. I assumed, since it was missing from the
command line, that crash_kexec_post_notifiers was disabled. Only after
a rather long reproduction and analysis process did I learn that Hyper-V
actually enables this setting unconditionally.

Users and debuggers alike would like to know when these things happen. I
think it would be good to print a message to the kernel log when this
happens, so that a grep for "crash_kexec_post_notifiers" shows relevant
results.

Signed-off-by: default avatarStephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220215013735.358327-1-stephen.s.brennan@oracle.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 6de74d10

drivers/hv/hv_common.c

+3 −1
Original line number Diff line number Diff line
@@ -79,8 +79,10 @@ int __init hv_common_init(void) 
	 * calling crash enlightment interface before running kdump

	 * kernel.

	 */

	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)

	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {

		crash_kexec_post_notifiers = true;

		pr_info("Hyper-V: enabling crash_kexec_post_notifiers\n");

	}



	/*

	 * Allocate the per-CPU state for the hypercall input arg.