From: Zhen Lei <thunder.leizhen@xxxxxxxxxx> The statistics function of softirq is supported by commit aa0ce5bbc2db ("softirq: introduce statistics for softirq") in 2009. At that time, 64-bit processors should not have many cores and would not face significant count overflow problems. Now it's common for a processor to have hundreds of cores. Assume that there are 100 cores and 10 TIMER_SOFTIRQ are generated per second, then the 32-bit sum will be overflowed after 50 days. For example: seq_put_decimal_ull(p, "softirq ", (unsigned long long)sum_softirq); for (i = 0; i < NR_SOFTIRQS; i++) seq_put_decimal_ull(p, " ", per_softirq_sums[i]); $ cat /proc/stat | tail -n 1 softirq 22929066124 9 2963267579 4128150 2618598635 546358555 0 \ 629391610 1326100278 74637 1956244783 Here, the sum of per_softirq_sums[] is 10044164236 and is not equal to 22929066124. Because integers overflowed. Therefore, change the type of local variable per_softirq_sums[] to u64. Fixes: d3d64df21d3d ("proc: export statistics for softirq to /proc") Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx> --- fs/proc/stat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/proc/stat.c b/fs/proc/stat.c index da60956b2915645..84aac577a50cabb 100644 --- a/fs/proc/stat.c +++ b/fs/proc/stat.c @@ -86,7 +86,7 @@ static int show_stat(struct seq_file *p, void *v) u64 guest, guest_nice; u64 sum = 0; u64 sum_softirq = 0; - unsigned int per_softirq_sums[NR_SOFTIRQS] = {0}; + u64 per_softirq_sums[NR_SOFTIRQS] = {0}; struct timespec64 boottime; user = nice = system = idle = iowait = -- 2.25.1