From: Eiichi Tsukata devel@etsukata.com
commit 6d54ceb539aacc3df65c89500e8b045924f3ef81 upstream.
Commit c5c27a0a5838 ("x86/stacktrace: Remove the pointless ULONG_MAX marker") removes ULONG_MAX marker from user stack trace entries but trace_user_stack_print() still uses the marker and it outputs unnecessary "??".
For example:
less-1911 [001] d..2 34.758944: <user stack trace> => <00007f16f2295910> => ?? => ?? => ?? => ?? => ?? => ?? => ??
The user stack trace code zeroes the storage before saving the stack, so if the trace is shorter than the maximum number of entries it can terminate the print loop if a zero entry is detected.
Link: http://lkml.kernel.org/r/20190630085438.25545-1-devel@etsukata.com
Cc: stable@vger.kernel.org Fixes: 4285f2fcef80 ("tracing: Remove the ULONG_MAX stack trace hackery") Signed-off-by: Eiichi Tsukata devel@etsukata.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/trace/trace_output.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-)
--- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1109,17 +1109,10 @@ static enum print_line_t trace_user_stac for (i = 0; i < FTRACE_STACK_ENTRIES; i++) { unsigned long ip = field->caller[i];
- if (ip == ULONG_MAX || trace_seq_has_overflowed(s)) + if (!ip || trace_seq_has_overflowed(s)) break;
trace_seq_puts(s, " => "); - - if (!ip) { - trace_seq_puts(s, "??"); - trace_seq_putc(s, '\n'); - continue; - } - seq_print_user_ip(s, mm, ip, flags); trace_seq_putc(s, '\n'); }