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Date:   Sat, 8 Jun 2019 18:26:59 +0800
From:   Baoquan He <bhe@redhat.com>
To:     Borislav Petkov <bp@alien8.de>
Cc:     lijiang <lijiang@redhat.com>, linux-kernel@vger.kernel.org,
        kexec@lists.infradead.org, tglx@linutronix.de, mingo@redhat.com,
        akpm@linux-foundation.org, dave.hansen@linux.intel.com,
        luto@kernel.org, peterz@infradead.org, x86@kernel.org,
        hpa@zytor.com, dyoung@redhat.com, Thomas.Lendacky@amd.com
Subject: Re: [PATCH 0/3 v11] add reserved e820 ranges to the kdump kernel
 e820 table
Message-ID: <20190608102659.GA9130@MiWiFi-R3L-srv>
References: <20190423013007.17838-1-lijiang@redhat.com>
 <12847a03-3226-0b29-97b5-04d404410147@redhat.com>
 <20190607174211.GN20269@zn.tnic>
 <20190608035451.GB26148@MiWiFi-R3L-srv>
 <20190608091030.GB32464@zn.tnic>
 <20190608100139.GC26148@MiWiFi-R3L-srv>
 <20190608100623.GA9138@zn.tnic>
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On 06/08/19 at 12:06pm, Borislav Petkov wrote:
> On Sat, Jun 08, 2019 at 06:01:39PM +0800, Baoquan He wrote:
> > OK, it may be different with the case we met, if panic happened when
> > load a kdump kernel.
> > 
> > We can load with 'kexec -l' or 'kexec -p', but can't boot after triggering
> > crash or execute 'kexec -e' to do kexec jumping.
> 
> No, I load a kdump kernel properly with this command:
> 
>  kexec -s -p /boot/vmlinuz-5.2.0-rc3+ --initrd=/boot/initrd.img-5.2.0-rc3+ --command-line="maxcpus=1 root=/dev/sda5 ro debug ignore_loglevel
> log_buf_len=16M no_console_suspend net.ifnames=0 systemd.log_target=null mem_encrypt=on kvm_amd.sev=1 nr_cpus=1 irqpoll reset_devices vga=normal
> LANG=en_US.UTF-8 earlyprintk=serial cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail acpi_no_memhotplug
> transparent_hugepage=never disable_cpu_apicid=0"
> 
> And that succeeds judging from
> 
> $ grep . /sys/kernel/kexec_*
> 
> Then I trigger a panic with
> 
> echo c > /proc/sysrq-trigger
> 
> and this is where it hangs and doesn't load the kdump kernel.

OK, I see. Then it should be the issue we have met and talked about with
Tom.
https://lkml.kernel.org/r/20190604134952.GC26891@MiWiFi-R3L-srv

You can apply Tom's patch as below. I tested it, it can make kexec
kernel succeed to boot, but failed for kdump kernel booting. The kdump
kernel can boot till the end of kernel initialization, then hang with a
call trace. I have pasted the log in the above thread. Haven't got the
reason.
http://lkml.kernel.org/r/508c2853-dc4f-70a6-6fa8-97c950dc31c6@amd.com