Messages in this thread | | | From | Marco Elver <> | Date | Wed, 30 Jun 2021 21:34:30 +0200 | Subject | Re: [V9fs-developer] KCSAN BUG report on p9_client_cb / p9_client_rpc |
| |
On Tue, 22 Jun 2021 at 23:03, Dominique Martinet <asmadeus@codewreck.org> wrote:
> jim.cromie@gmail.com wrote on Tue, Jun 22, 2021 at 02:55:19PM -0600: > > heres a fuller report - Im seeing some new stuff here.
There are lots of known data races. A non-exhaustive list can be seen here: https://syzkaller.appspot.com/upstream?manager=ci2-upstream-kcsan-gce
> Thanks, the one two should be the same as p9_client_cb / p9_client_rpc > and p9_client_cb / p9_virtio_zc_request are very similar, and also the > same to the first you had, so the patch didn't really work. > > I thought after sending it that it probably needs to be tag = > READ_ONCE(req->tc.tag) instead of just assigning it... Would you mind > trying that? > > > Im running in a vm, using virtme, which uses 9p to share host filesystems > > since 1st report to you, Ive added --smp 2 to my testing, it seems to > > have increased reporting > > I'm ashamed to say I've just never tried KCSAN... I can give it a try over > the next few weeks* if that patch + READ_ONCE doesn't cut it
In case it helps, we have this LWN article series: https://lwn.net/Articles/816850/
Paul McKenney also kindly wrote a summary of some parts of it: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/memory-model/Documentation/access-marking.txt
There are some upcoming changes to KCSAN that can help filter some data races that aren't too interesting today -- see linux-next and set CONFIG_KCSAN_PERMISSIVE=y (the opposite of that is CONFIG_KCSAN_STRICT=y, but not recommended at this time unless you're writing complex concurrent code).
Thanks, -- Marco
| |