Hello, On (04/02/18 09:58), Wen Yang wrote: > There would be so many same lines printed by frequent printk if one > disk went wrong, like, > [ 546.185242] sd 0:1:0:0: rejecting I/O to offline device > [ 546.185258] sd 0:1:0:0: rejecting I/O to offline device > [ 546.185280] sd 0:1:0:0: rejecting I/O to offline device > [ 546.185307] sd 0:1:0:0: rejecting I/O to offline device > [ 546.185334] sd 0:1:0:0: rejecting I/O to offline device > [ 546.185364] sd 0:1:0:0: rejecting I/O to offline device > [ 546.185390] sd 0:1:0:0: rejecting I/O to offline device > [ 546.185410] sd 0:1:0:0: rejecting I/O to offline device > For slow serial console, the frequent printk may be blocked for a > long time, and if any spin_lock has been acquired before the printk > like in scsi_request_fn, watchdog could be triggered. Did you test the patch? Rate limiting does not completely remove printk calls. printk is still there, in a loop under spin_lock. A big enough I/O request queue can cause the same lockup problems. -ss
