Hello, Andrew and Linus. We are stuck because Peter cannot respond. I think it is time to send this patch to linux-next. What do you think?
On 2021/01/20 19:18, Dmitry Vyukov wrote: > On Wed, Jan 20, 2021 at 11:12 AM Tetsuo Handa > <[email protected]> wrote: >> >> Since syzkaller continues various test cases until the kernel crashes, >> syzkaller tends to examine more locking dependencies than normal systems. >> As a result, syzbot is reporting that the fuzz testing was terminated >> due to hitting upper limits lockdep can track [1] [2] [3]. >> >> Peter Zijlstra does not want to allow tuning these limits via kernel >> config options, for such change discourages thinking. But analysis via >> /proc/lockdep* did not show any obvious culprit [4] [5]. It is possible >> that many hundreds of kn->active lock instances are to some degree >> contributing to these problems, but there is no means to verify whether >> these instances are created for protecting same callback functions. >> Unless Peter provides a way to make these instances per "which callback >> functions the lock instance will call (identified by something like MD5 >> of string representations of callback functions which each lock instance >> will protect)" than plain "serial number", I don't think that we can >> verify the culprit. >> >> [1] >> https://syzkaller.appspot.com/bug?id=3d97ba93fb3566000c1c59691ea427370d33ea1b >> [2] >> https://syzkaller.appspot.com/bug?id=381cb436fe60dc03d7fd2a092b46d7f09542a72a >> [3] >> https://syzkaller.appspot.com/bug?id=a588183ac34c1437fc0785e8f220e88282e5a29f >> [4] >> https://lkml.kernel.org/r/[email protected] >> [5] >> https://lkml.kernel.org/r/[email protected] >> >> Reported-by: syzbot <[email protected]> >> Reported-by: syzbot <[email protected]> >> Reported-by: syzbot <[email protected]> >> Signed-off-by: Tetsuo Handa <[email protected]> >> Acked-by: Dmitry Vyukov <[email protected]> > > Thanks for your persistence! > I still support this. And assessment of lockdep stats on overflow > seems to confirm it's just a very large lock graph triggered by > syzkaller. >
