From: Dmitry Safonov <dima@xxxxxxxxxx>
Subject: kdb: don't play with console_loglevel
Print the stack trace with KERN_EMERG - it should be always visible.
Playing with console_loglevel is a bad idea as there may be more messages
printed than wanted. Also the stack trace might be not printed at all if
printk() was deferred and console_loglevel was raised back before the
trace got flushed.
Unfortunately, after rebasing on commit 2277b492582d ("kdb: Fix stack
crawling on 'running' CPUs that aren't the master"), kdb_show_stack() uses
now kdb_dump_stack_on_cpu(), which for now won't be converted as it uses
dump_stack() instead of show_stack().
Convert for now the branch that uses show_stack() and remove
console_loglevel exercise from that case.
Link: http://lkml.kernel.org/r/20200418201944.482088-48-dima@xxxxxxxxxx
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Acked-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Cc: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/debug/kdb/kdb_bt.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
--- a/kernel/debug/kdb/kdb_bt.c~kdb-dont-play-with-console_loglevel
+++ a/kernel/debug/kdb/kdb_bt.c
@@ -21,17 +21,18 @@
static void kdb_show_stack(struct task_struct *p, void *addr)
{
- int old_lvl = console_loglevel;
-
- console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
kdb_trap_printk++;
- if (!addr && kdb_task_has_cpu(p))
+ if (!addr && kdb_task_has_cpu(p)) {
+ int old_lvl = console_loglevel;
+
+ console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
kdb_dump_stack_on_cpu(kdb_process_cpu(p));
- else
- show_stack(p, addr);
+ console_loglevel = old_lvl;
+ } else {
+ show_stack_loglvl(p, addr, KERN_EMERG);
+ }
- console_loglevel = old_lvl;
kdb_trap_printk--;
}
_
