On Mon, Oct 30, 2017 at 7:12 PM, Cong Wang <xiyou.wangc...@gmail.com> wrote: > On Mon, Oct 30, 2017 at 3:39 PM, Lucas Bates <luc...@mojatatu.com> wrote: >> e.On Thu, Oct 26, 2017 at 9:24 PM, Cong Wang <xiyou.wangc...@gmail.com> >> wrote: >>> Recently, the RCU callbacks used in TC filters and TC actions keep >>> drawing my attention, they introduce at least 4 race condition bugs: >> <snip> >>> As suggested by Paul, we could defer the work to a workqueue and >>> gain the permission of holding RTNL again without any performance >>> impact, however, in tcf_block_put() we could have a deadlock when >>> flushing workqueue while hodling RTNL lock, the trick here is to >>> defer the work itself in workqueue and make it queued after all >>> other works so that we keep the same ordering to avoid any >>> use-after-free. Please see the first patch for details. >> >> Cong, I don't believe the problem's been resolved just yet.... I have >> a new kernel, compiled just today and I'm still tripping over a kernel >> bug in this scenario when I run Chris' new test case. >> > > Without a stack trace, I can't do anything. "a kernel bug" could > be anything, why do you believe it is caused by this patchset? > (Sending again due to email format issues)
The stack trace I saw touched on the same code that was affected by the patchset. I've sent a photo of the trace to you directly - I'm sorry, I should have sent it earlier. I also apologize for having to send the photo but I was doing the testing on a small device lacking any kind of serial console access. >> I'm doing this on a machine where I don't have a spare device to use >> on the run. Instead I created a veth pair that will have one end >> migrated into the container. >> >> The bug isn't consistent. I'm running into it anywhere between one and >> four runs of the d052 test case. >> >> Steps to reproduce: >> >> sudo ip li add foo type veth >> sudo ./tdc.py -d foo -c flower >> [repeat until kernel bug encountered] > > I tested with basic and u32 filter, since it is not specific to any type > of filters, all filters had the same problem. I will try flower filter too > before you provide a stack trace or a detailed report. If you need more information or need me to try something else, I'll be able to tomorrow.
