On Thu, Mar 25, 2021 at 8:10 PM Will Deacon <will@xxxxxxxxxx> wrote: > > On Thu, Mar 25, 2021 at 07:34:54PM +0100, Dmitry Vyukov wrote: > > On Thu, Mar 25, 2021 at 7:20 PM Will Deacon <will@xxxxxxxxxx> wrote: > > > > > > On Thu, Mar 18, 2021 at 08:34:16PM +0100, Dmitry Vyukov wrote: > > > > On Thu, Mar 18, 2021 at 8:31 PM syzbot > > > > <syzbot+0b036374a865ba0efa8e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > > Hello, > > > > > > > > > > syzbot found the following issue on: > > > > > > > > > > HEAD commit: bf152b0b Merge tag 'for_linus' of git://git.kernel.org/pub.. > > > > > git tree: upstream > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=17d5264ed00000 > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=2c9917c41f0bc04b > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=0b036374a865ba0efa8e > > > > > userspace arch: arm64 > > > > > > > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > > Reported-by: syzbot+0b036374a865ba0efa8e@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > > > > > watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [syz-executor.1:3684] > > > > > > > > +Will, arm > > > > > > > > If I am reading this commit correctly, this is caused by: > > > > > > > > commit cae118b6acc309539b33339e846cbb19187c164c > > > > Author: Will Deacon > > > > Date: Wed Mar 3 13:49:27 2021 +0000 > > > > arm64: Drop support for CMDLINE_EXTEND > > > > > > > > syzbot passes lots of critical things in CONFIG_CMDLINE: > > > > https://github.com/google/syzkaller/blob/c3c81c94865791469d376eba84f4a2d7763d3f71/dashboard/config/linux/upstream-arm64-kasan.config#L495 > > > > but also wants the bootloader args to be appended. > > > > What is the way to do it now? > > > > > > For now, there isn't a way to do it with CONFIG_CMDLINE, so I think you can > > > either: > > > > > > * Revert my patch for your kernels > > > * Pass the arguments via QEMU's -append option > > > * Take a look at one of the series which should hopefully add this > > > functionality back (but with well-defined semantics) [1] [2] > > > > Unfortunately none of these work for syzbot (and I assume other > > testing environments). > > > > syzbot does not support custom patches by design: > > http://bit.do/syzbot#no-custom-patches > > As any testing system, it tests the official trees. > > > > It's not humans who start these VMs, so it's not as easy as changing > > the command line after typing... > > There is no support for passing args specifically to qemu, syzkaller > > support not just qemu, so these things are specifically localized in > > the config. Additionally there is an issue of communicating all these > > scattered details to developers in bug reports. Currently syzbot > > reports the kernel config and it as well captures command line. > > > > Could you revert the patch? Is there any point in removing the > > currently supported feature before the new feature lands? > > Well, we only just merged it (in 5.10 I think?), and the semantics of the > new version will be different, so I really don't see the value in supporting > both (even worse, Android has its own implementation which is different > again). The timeline was: we merged CMDLINE_EXTEND, then we noticed it was > broken, my fixes were rejected, so we removed the feature rather than > support the broken version. In the relatively small window while it was > merged, syzbot started using it :( I didn't realize it was just introduced :) We used CMDLINE_EXTEND on x86, and I looked for a similar option for arm64 and found it. > So I really think the best bet is to wait until the patches are sorted out. > I think Christophe is about to spin a new version, and I reviewed his last > copy, so I don't see this being far off, If it's expected to be merged soon, let's wait.
