From: chenqiwu <chenqiwu(a)xiaomi.com&gt; Fix for the "log -a" option. The printk logbuf is a ring buffer, if log_first_idx is larger than log_next_idx, there are two buffer zones must be handled for logdump: 1) [log_first_idx, log_buf_len] 2) [0, log_next_idx] However, the original code ignores the logdump for the second buffer zone if log_first_idx is larger than log_next_idx. Without this patch, the option fails with the following error message "duplicate log_buf message pointer". Signed-off-by: chenqiwu <chenqiwu(a)xiaomi.com&gt; --- kernel.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel.c b/kernel.c index 68ee282..7604fac 100644 --- a/kernel.c +++ b/kernel.c @@ -5278,8 +5278,12 @@ dump_variable_length_record_log(int msg_flags) idx = log_next(idx, logbuf); if (idx >= log_buf_len) { - error(INFO, "\ninvalid log_buf entry encountered\n"); - break; + if (log_first_idx > log_next_idx) + idx = 0; + else { + error(INFO, "\ninvalid log_buf entry encountered\n"); + break; + } } if (CRASHDEBUG(1) && (idx == log_next_idx)) -- 1.9.1