From: Stephen Brennan Date: Tue, 15 Feb 2022 01:37:35 +0000 (-0800) Subject: drivers: hv: log when enabling crash_kexec_post_notifiers X-Git-Tag: v5.18-rc1~138^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d57d6fe5bf3463aad1332ecfc7555a6888b04fd9;p=thirdparty%2Fkernel%2Flinux.git 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: Stephen Brennan Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20220215013735.358327-1-stephen.s.brennan@oracle.com Signed-off-by: Wei Liu --- diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c index 181d16bbf49d7..c1dd21d0d7ef8 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -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.