On Wed, Apr 29, 2020 at 11:49:37AM +0200, Greg KH wrote: > On Wed, Apr 29, 2020 at 07:46:26AM +0000, Luis Chamberlain wrote: > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > > index 5c52976bd762..383045f67cb8 100644 > > --- a/kernel/trace/blktrace.c > > +++ b/kernel/trace/blktrace.c > > @@ -516,6 +518,11 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, > > */ > > strreplace(buts->name, '/', '_'); > > > > + if (q->blk_trace) { > > + pr_warn("Concurrent blktraces are not allowed\n"); > > + return -EBUSY; > > You have access to a block device here, please use dev_warn() instead > here for that, that makes it obvious as to what device a "concurrent > blktrace" was attempted for. The block device may be empty, one example is for scsi-generic, but I'll use buts->name. Luis