mm: kfence: print the elapsed time for allocated/freed track

Print the elapsed time for the allocated or freed track, which can be
useful in some debugging scenarios.

Link: https://lkml.kernel.org/r/20240807025627.37419-1-qiwu.chen@transsion.com
Signed-off-by: qiwu.chen <qiwu.chen@transsion.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: chenqiwu <qiwu.chen@transsion.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/kfence/report.c b/mm/kfence/report.c
index c509aed..73a6fe4 100644 (file)
--- a/mm/kfence/report.c
+++ b/mm/kfence/report.c
@@ -16,6 +16,7 @@
 #include <linux/sprintf.h>
 #include <linux/stacktrace.h>
 #include <linux/string.h>
+#include <linux/sched/clock.h>
 #include <trace/events/error_report.h>
 
 #include <asm/kfence.h>
@@ -108,11 +109,14 @@ static void kfence_print_stack(struct seq_file *seq, const struct kfence_metadat
        const struct kfence_track *track = show_alloc ? &meta->alloc_track : &meta->free_track;
        u64 ts_sec = track->ts_nsec;
        unsigned long rem_nsec = do_div(ts_sec, NSEC_PER_SEC);
+       u64 interval_nsec = local_clock() - meta->alloc_track.ts_nsec;
+       unsigned long rem_interval_nsec = do_div(interval_nsec, NSEC_PER_SEC);
 
        /* Timestamp matches printk timestamp format. */
-       seq_con_printf(seq, "%s by task %d on cpu %d at %lu.%06lus:\n",
+       seq_con_printf(seq, "%s by task %d on cpu %d at %lu.%06lus (%lu.%06lus ago):\n",
                       show_alloc ? "allocated" : "freed", track->pid,
-                      track->cpu, (unsigned long)ts_sec, rem_nsec / 1000);
+                      track->cpu, (unsigned long)ts_sec, rem_nsec / 1000,
+                      (unsigned long)interval_nsec, rem_interval_nsec / 1000);
 
        if (track->num_stack_entries) {
                /* Skip allocation/free internals stack. */