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 patches. 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:: Patches currently in stable-queue which might be from gpiccoli@xxxxxxxxxx are queue-5.17/docs-sysctl-kernel-add-missing-bit-to-panic_print.patch