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| author | Odin Ugedal <odin@uged.al> | 2021-06-29 15:14:52 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-07-02 16:58:24 +0300 |
| commit | 72d0ad7cb5bad265adb2014dbe46c4ccb11afaba (patch) | |
| tree | 93567a1879448c91711ed8ff217a59c039403767 | |
| parent | ceb6ba45dc8074d2a1ec1117463dc94a20d4203d (diff) | |
| download | linux-72d0ad7cb5bad265adb2014dbe46c4ccb11afaba.tar.xz | |
sched/fair: Fix CFS bandwidth hrtimer expiry type
The time remaining until expiry of the refresh_timer can be negative.
Casting the type to an unsigned 64-bit value will cause integer
underflow, making the runtime_refresh_within return false instead of
true. These situations are rare, but they do happen.
This does not cause user-facing issues or errors; other than
possibly unthrottling cfs_rq's using runtime from the previous period(s),
making the CFS bandwidth enforcement less strict in those (special)
situations.
Signed-off-by: Odin Ugedal <odin@uged.al>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Link: https://lore.kernel.org/r/20210629121452.18429-1-odin@uged.al
| -rw-r--r-- | kernel/sched/fair.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1e263c9cdc13..1b15a19910a3 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5054,7 +5054,7 @@ static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) { struct hrtimer *refresh_timer = &cfs_b->period_timer; - u64 remaining; + s64 remaining; /* if the call-back is running a quota refresh is already occurring */ if (hrtimer_callback_running(refresh_timer)) @@ -5062,7 +5062,7 @@ static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) /* is a quota refresh about to occur? */ remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); - if (remaining < min_expire) + if (remaining < (s64)min_expire) return 1; return 0; |