On Fri, May 27, 2022 at 06:54:29PM +0200, Michal Koutný wrote: > Hello Tadeusz. > > On Fri, May 27, 2022 at 09:39:20AM -0700, Tadeusz Struk <tadeusz.struk@xxxxxxxxxx> wrote: > > As far as I can see we are trying to test the same thing suggested by Tejun. > > I just sent a test request to try this: > > https://github.com/tstruk/linux/commit/master > > Yup, I've added few more prints to get more fine-grained resolution. > Also, I decided to use ftrace printk not to interfere with timing too > much (due to the original race hypothesis). > > > Let me know if you have any more tests to run and I will hold off until > > you are done. > > My latest attempt is [1] (tip 5500e05d82fd5b5db2203eedb3f786857d3ccbea). > > So far, I'm not convinced, I extract the complete ftrace buffer from the > syzbot runs, so I'm not drawing any conclusions from the traces I've > got. I'm not going to continue today. You may have more luck with your > plain printk (if it's just imbalance and it avoids printk locking > sensitive paths). At least for triaging, it may be easier to use bpftrace to attach kprobes to the get/put functions with the right filter and record the kstack counts. Thanks. -- tejun
