In DAMON_STAT's damon_stat_damon_call_fn(), time_before_eq() is used to avoid unnecessarily frequent stat update. On 32-bit systems, the kernel initializes jiffies to "-5 minutes" to make jiffies wrap bugs appear earlier. However, this causes time_before_eq() in DAMON_STAT to unexpectedly return true during the first 5 minutes after boot on 32-bit systems (see [1] for more explanation, which fixes another jiffies-related issue in DAMON). As a result, DAMON_STAT does not update any monitoring results during that period, which can be more confusing when DAMON_STAT_ENABLED_DEFAULT is enabled. Fix it by setting last_refresh_jiffies to jiffies at startup. [1] https://lkml.kernel.org/r/20250822025057.1740854-1-ekffu200098@gmail.com Fixes: fabdd1e911da ("mm/damon/stat: calculate and expose estimated memory bandwidth") Signed-off-by: Quanmin Yan --- mm/damon/stat.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/damon/stat.c b/mm/damon/stat.c index 6c4503d2aee3..6dc3e18de910 100644 --- a/mm/damon/stat.c +++ b/mm/damon/stat.c @@ -132,6 +132,9 @@ static int damon_stat_damon_call_fn(void *data) struct damon_ctx *c = data; static unsigned long last_refresh_jiffies; + if (unlikely(!last_refresh_jiffies)) + last_refresh_jiffies = jiffies; + /* avoid unnecessarily frequent stat update */ if (time_before_eq(jiffies, last_refresh_jiffies + msecs_to_jiffies(5 * MSEC_PER_SEC))) -- 2.43.0