On Fri, Jun 9, 2017 at 11:43 AM, Krister Johansen <k...@templeofstupid.com> wrote: > On Fri, Jun 09, 2017 at 11:18:44AM -0700, Cong Wang wrote: >> On Thu, Jun 8, 2017 at 1:12 PM, Krister Johansen >> <k...@templeofstupid.com> wrote: >> > The way this works is that if there's still a reference on the dst entry >> > at the time we try to free it, it gets placed in the gc list by >> > __dst_free and the dst_destroy() call is invoked by the gc task once the >> > refcount is 0. If the gc task processes a 10th or less of its entries >> > on a single pass, it inreases the amount of time it waits between gc >> > intervals. >> > >> > Looking at the gc_task intervals, they started at 663ms when we invoked >> > __dst_free(). After that, they increased to 1663, 3136, 5567, 8191, >> > 10751, and 14848. The release that set the refcnt to 0 on our dst entry >> > occurred after the gc_task was enqueued for 14 second interval so we had >> > to wait longer than the warning time in wait_allrefs in order for the >> > dst entry to get free'd and the hold on 'lo' to be released. >> > >> >> I am glad to see you don't have a dst leak here. >> >> But from my experience of a similar bug (refcnt wait on lo), this goes >> infinitely rather than just 14sec, so it looked more like a real leak than >> just a gc delay. So in your case, this annoying warning eventually >> disappears, right? > > That's correct. The problem occurs intermittently, and the warnings are > less frequent than the interval in netdev_wait_allrefs(). At least when > I observed it, it tended to conincide with our controlplane canary > issuing an API call that lead to a network namespace teardown on the > dataplane.
Great! Then the bug I saw is different from this one and it is probably a dst leak. Thanks.
