On 2/19/2025 8:58 AM, Paul E. McKenney wrote: > On Wed, Feb 19, 2025 at 08:25:38AM -0500, Joel Fernandes wrote: >> On Tue, Feb 18, 2025 at 09:47:27AM -0800, syzbot wrote: >>> Hello, >>> >>> syzbot found the following issue on: >>> >>> HEAD commit: a64dcfb451e2 Linux 6.14-rc2 >>> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci >>> console output: https://syzkaller.appspot.com/x/log.txt?x=12398f18580000 >>> kernel config: https://syzkaller.appspot.com/x/.config?x=c9c47badcd079906 >>> dashboard link: https://syzkaller.appspot.com/bug?extid=ae5b16688c0c675b1a1f >>> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 >>> userspace arch: arm64 >>> >>> Unfortunately, I don't have any reproducer for this issue yet. >>> >>> Downloadable assets: >>> disk image: https://storage.googleapis.com/syzbot-assets/c0a862fcec77/disk-a64dcfb4.raw.xz >>> vmlinux: https://storage.googleapis.com/syzbot-assets/f03793fc001b/vmlinux-a64dcfb4.xz >>> kernel image: https://storage.googleapis.com/syzbot-assets/ae71c33eae14/Image-a64dcfb4.gz.xz >>> >>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>> Reported-by: syzbot+ae5b16688c0c675b1a1f@xxxxxxxxxxxxxxxxxxxxxxxxx >>> >>> ------------[ cut here ]------------ >>> WARNING: CPU: 0 PID: 6430 at kernel/rcu/srcutree.c:1798 srcu_invoke_callbacks+0x368/0x3d8 >> >> This is weird, happens to be WARN_ON_ONCE(ready_cbs.len); in >> srcu_invoke_callbacks(). > > Thank you for tracking that down! Sure! >> Perhaps, stack corruption or the SRCU cblist's ->seglen got corrupted? > > That has been the usual cause. And a double call_srcu() is a common > cause of ->cblist corruption. We have CONFIG_DEBUG_OBJECTS_RCU_HEAD=y > set up for SRCU as well as for RCU, it appears, so perhaps retry with > that should this ever become reproducible? Makes sense, will keep an eye out for it! thanks, - Joel
