From: Guilherme G. Piccoli gpiccoli@igalia.com
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@infradead.org: fix table format warning] Link: https://lkml.kernel.org/r/20220109055635.6999-1-rdunlap@infradead.org
Link: https://lkml.kernel.org/r/20211109202848.610874-1-gpiccoli@igalia.com Link: https://lkml.kernel.org/r/20211109202848.610874-2-gpiccoli@igalia.com Fixes: de6da1e8bcf0 ("panic: add an option to replay all the printk message in buffer") Signed-off-by: Guilherme G. Piccoli gpiccoli@igalia.com Reviewed-by: Feng Tang feng.tang@intel.com Cc: Luis Chamberlain mcgrof@kernel.org Cc: Kees Cook keescook@chromium.org Cc: Iurii Zaikin yzaikin@google.com Cc: Samuel Iglesias Gonsalvez siglesias@igalia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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::