Changelog
v2
- Added review-by's
- Sync with mainline
Allow to study performance shutdown via kexec reboot calls by having kmsg
log saved via pstore.
Previous submissions
v1 https://lore.kernel.org/lkml/[email protected]
Pavel Tatashin (1):
kexec: dump kmessage before machine_kexec
kernel/kexec_core.c | 2 ++
1 file changed, 2 insertions(+)
--
2.25.1
kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before
machine_restart(), machine_halt(), machine_power_off(), the only one that
is missing is machine_kexec().
The dmesg output that it contains can be used to study the shutdown
performance of both kernel and systemd during kexec reboot.
Here is example of dmesg data collected after kexec:
root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail
...
<6>[ 70.914592] psci: CPU3 killed (polled 0 ms)
<5>[ 70.915705] CPU4: shutdown
<6>[ 70.916643] psci: CPU4 killed (polled 4 ms)
<5>[ 70.917715] CPU5: shutdown
<6>[ 70.918725] psci: CPU5 killed (polled 0 ms)
<5>[ 70.919704] CPU6: shutdown
<6>[ 70.920726] psci: CPU6 killed (polled 4 ms)
<5>[ 70.921642] CPU7: shutdown
<6>[ 70.922650] psci: CPU7 killed (polled 0 ms)
Signed-off-by: Pavel Tatashin <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
Reviewed-by: Bhupesh Sharma <[email protected]>
---
kernel/kexec_core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 4f8efc278aa7..e253c8b59145 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -37,6 +37,7 @@
#include <linux/compiler.h>
#include <linux/hugetlb.h>
#include <linux/objtool.h>
+#include <linux/kmsg_dump.h>
#include <asm/page.h>
#include <asm/sections.h>
@@ -1180,6 +1181,7 @@ int kernel_kexec(void)
machine_shutdown();
}
+ kmsg_dump(KMSG_DUMP_SHUTDOWN);
machine_kexec(kexec_image);
#ifdef CONFIG_KEXEC_JUMP
--
2.25.1
On 01/26/21 at 03:41pm, Pavel Tatashin wrote:
> kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before
> machine_restart(), machine_halt(), machine_power_off(), the only one that
> is missing is machine_kexec().
>
> The dmesg output that it contains can be used to study the shutdown
> performance of both kernel and systemd during kexec reboot.
>
> Here is example of dmesg data collected after kexec:
>
> root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail
> ...
> <6>[ 70.914592] psci: CPU3 killed (polled 0 ms)
> <5>[ 70.915705] CPU4: shutdown
> <6>[ 70.916643] psci: CPU4 killed (polled 4 ms)
> <5>[ 70.917715] CPU5: shutdown
> <6>[ 70.918725] psci: CPU5 killed (polled 0 ms)
> <5>[ 70.919704] CPU6: shutdown
> <6>[ 70.920726] psci: CPU6 killed (polled 4 ms)
> <5>[ 70.921642] CPU7: shutdown
> <6>[ 70.922650] psci: CPU7 killed (polled 0 ms)
>
> Signed-off-by: Pavel Tatashin <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
> Reviewed-by: Petr Mladek <[email protected]>
> Reviewed-by: Bhupesh Sharma <[email protected]>
> ---
> kernel/kexec_core.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 4f8efc278aa7..e253c8b59145 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -37,6 +37,7 @@
> #include <linux/compiler.h>
> #include <linux/hugetlb.h>
> #include <linux/objtool.h>
> +#include <linux/kmsg_dump.h>
>
> #include <asm/page.h>
> #include <asm/sections.h>
> @@ -1180,6 +1181,7 @@ int kernel_kexec(void)
> machine_shutdown();
> }
>
> + kmsg_dump(KMSG_DUMP_SHUTDOWN);
> machine_kexec(kexec_image);
Looks good to me, thx.
Acked-by: Baoquan He <[email protected]>
>
> #ifdef CONFIG_KEXEC_JUMP
> --
> 2.25.1
>
>
> _______________________________________________
> kexec mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/kexec
>
Pavel Tatashin <[email protected]> writes:
> kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before
> machine_restart(), machine_halt(), machine_power_off(), the only one that
> is missing is machine_kexec().
>
> The dmesg output that it contains can be used to study the shutdown
> performance of both kernel and systemd during kexec reboot.
>
> Here is example of dmesg data collected after kexec:
As long was we keep kmsg_dump out of the crash_kexec path where
it completely breaks kexec on panic this seems a reasonable thing to do.
On the ordinary kernel_kexec path everything is expected to be working.
Is kmsg_dump expected to work after all of the device drivers
are shut down? Otherwise this placement of kmsg_dump is too late.
Eric
> root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail
> ...
> <6>[ 70.914592] psci: CPU3 killed (polled 0 ms)
> <5>[ 70.915705] CPU4: shutdown
> <6>[ 70.916643] psci: CPU4 killed (polled 4 ms)
> <5>[ 70.917715] CPU5: shutdown
> <6>[ 70.918725] psci: CPU5 killed (polled 0 ms)
> <5>[ 70.919704] CPU6: shutdown
> <6>[ 70.920726] psci: CPU6 killed (polled 4 ms)
> <5>[ 70.921642] CPU7: shutdown
> <6>[ 70.922650] psci: CPU7 killed (polled 0 ms)
>
> Signed-off-by: Pavel Tatashin <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
> Reviewed-by: Petr Mladek <[email protected]>
> Reviewed-by: Bhupesh Sharma <[email protected]>
> ---
> kernel/kexec_core.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 4f8efc278aa7..e253c8b59145 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -37,6 +37,7 @@
> #include <linux/compiler.h>
> #include <linux/hugetlb.h>
> #include <linux/objtool.h>
> +#include <linux/kmsg_dump.h>
>
> #include <asm/page.h>
> #include <asm/sections.h>
> @@ -1180,6 +1181,7 @@ int kernel_kexec(void)
> machine_shutdown();
> }
>
> + kmsg_dump(KMSG_DUMP_SHUTDOWN);
> machine_kexec(kexec_image);
>
> #ifdef CONFIG_KEXEC_JUMP
On Thu, Jan 28, 2021 at 3:01 PM Eric W. Biederman <[email protected]> wrote:
>
> Pavel Tatashin <[email protected]> writes:
>
> > kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before
> > machine_restart(), machine_halt(), machine_power_off(), the only one that
> > is missing is machine_kexec().
> >
> > The dmesg output that it contains can be used to study the shutdown
> > performance of both kernel and systemd during kexec reboot.
> >
> > Here is example of dmesg data collected after kexec:
>
> As long was we keep kmsg_dump out of the crash_kexec path where
> it completely breaks kexec on panic this seems a reasonable thing to do.
> On the ordinary kernel_kexec path everything is expected to be working.
This is an ordinary kexec reboot path, not kdump.
>
> Is kmsg_dump expected to work after all of the device drivers
> are shut down? Otherwise this placement of kmsg_dump is too late.
Yes it is. It is called after device_shutdown(); in all other places.
Thank you,
Pasha