[PATCH 5.16 1003/1017] docs: sysctl/kernel: add missing bit to panic_print

From: Greg Kroah-Hartman
Date: Tue Apr 05 2022 - 10:07:25 EST

From: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>

commit a1ff1de00db21ecb956213f046b79741b64c6b65 upstream.

Patch series "Some improvements on panic_print".

This is a mix of a documentation fix with some additions to the
"panic_print" syscall / parameter. The goal here is being able to collect
all CPUs backtraces during a panic event and also to enable "panic_print"
in a kdump event - details of the reasoning and design choices in the

This patch (of 3):

Commit de6da1e8bcf0 ("panic: add an option to replay all the printk
message in buffer") added a new bit to the sysctl/kernel parameter
"panic_print", but the documentation was added only in
kernel-parameters.txt, not in the sysctl guide.

Fix it here by adding bit 5 to sysctl admin-guide documentation.

[rdunlap@xxxxxxxxxxxxx: fix table format warning]
Link: https://lkml.kernel.org/r/20220109055635.6999-1-rdunlap@xxxxxxxxxxxxx

Link: https://lkml.kernel.org/r/20211109202848.610874-1-gpiccoli@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20211109202848.610874-2-gpiccoli@xxxxxxxxxx
Fixes: de6da1e8bcf0 ("panic: add an option to replay all the printk message in buffer")
Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>
Reviewed-by: Feng Tang <feng.tang@xxxxxxxxx>
Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Iurii Zaikin <yzaikin@xxxxxxxxxx>
Cc: Samuel Iglesias Gonsalvez <siglesias@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Documentation/admin-guide/sysctl/kernel.rst | 1 +
1 file changed, 1 insertion(+)

--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -795,6 +795,7 @@ bit 1 print system memory info
bit 2 print timer info
bit 3 print locks info if ``CONFIG_LOCKDEP`` is on
bit 4 print ftrace buffer
+bit 5 print all printk messages in buffer
===== ============================================

So for example to print tasks and memory info on panic, user can::