On 8/25/22 9:25 PM, gumi@xxxxxxxxxxxxxxxxx wrote: > On 8/25/22 00:09, Gu Mi wrote: >> The problem occurs in two async processes, One is when a new IO calls >> the blk_mq_start_request() interface to start sending,The other is >> that the block layer timer process calls the blk_mq_req_expired >> interface to check whether there is an IO timeout. >> >> When an instruction out of sequence occurs between blk_add_timer and >> WRITE_ONCE(rq->state,MQ_RQ_IN_FLIGHT) in the interface >> blk_mq_start_request,at this time, the block timer is checking the >> new IO timeout, Since the req status has been set to MQ_RQ_IN_FLIGHT >> and >> req->deadline is 0 at this time, the new IO will be misjudged as a >> timeout. >> >> Our repair plan is for the deadline to be 0, and we do not think that >> a timeout occurs. At the same time, because the jiffies of the 32-bit >> system will be reversed shortly after the system is turned on, we >> will add 1 jiffies to the deadline at this time. >> >> Signed-off-by: Gu Mi <gumi@xxxxxxxxxxxxxxxxx> >> --- >> v1->v2: >> >> time_after_eq() can handle the overflow, so remove the change on >> 32-bit in blk_add_timer(). >> >> block/blk-mq.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/block/blk-mq.c b/block/blk-mq.c index 4b90d2d..6defaa1 >> 100644 >> --- a/block/blk-mq.c >> +++ b/block/blk-mq.c >> @@ -1451,6 +1451,8 @@ static bool blk_mq_req_expired(struct request *rq, unsigned long *next) >> return false; >> >> deadline = READ_ONCE(rq->deadline); >> + if (unlikely(deadline == 0)) >> + return false; >> if (time_after_eq(jiffies, deadline)) >> return true; >> > > rq->deadline == 0 can be a valid deadline value so the above patch > doesn't look right to me. Gu, you need to fix your quoting of emails, these are impossible to read. That aside, I think there's a misunderstanding here. v1 has some parts and v2 has others. Please post a v3 that has the hunk that guarantees that deadline always has the lowest bit set if assigned, and the !deadline check as well. -- Jens Axboe --- Hi Jens Thanks for your reminder, I I will post a v3 patch later, my v3 patch and V1 patch are the same, please review again Thanks, Gu Mi
