Messages in this thread Patch in this message | | | From | Chengming Zhou <> | Subject | [PATCH] blk-iocost: fix very large vtime when iocg activate | Date | Mon, 16 May 2022 16:40:45 +0800 |
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When the first iocg activate after blk_iocost_init(), now->vnow maybe smaller than ioc->margins.target, cause very large vtarget since it's u64.
vtarget = now->vnow - ioc->margins.target; atomic64_add(vtarget - vtime, &iocg->vtime);
Then the iocg's vtime will be very large too, larger than now->vnow.
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> --- block/blk-iocost.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 5019dff524a4..a2ee12175c49 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1248,7 +1248,7 @@ static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; u64 last_period, cur_period; - u64 vtime, vtarget; + u64 vtime, vtarget = 0; int i; /* @@ -1290,7 +1290,8 @@ static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now) * Always start with the target budget. On deactivation, we throw away * anything above it. */ - vtarget = now->vnow - ioc->margins.target; + if (now->vnow > ioc->margins.target) + vtarget = now->vnow - ioc->margins.target; vtime = atomic64_read(&iocg->vtime); atomic64_add(vtarget - vtime, &iocg->vtime); -- 2.36.1
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