On Wed, Feb 19, 2025 at 10:09:06AM -0500, Joel Fernandes wrote: > > > 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: [email protected] > >>> > >>> ------------[ 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 > Hello all,
syzbot reports that this issue is still occurring on recent kernels, for example 6.16 (see https://syzkaller.appspot.com/bug?extid=ae5b16688c0c675b1a1f). And the "CONFIG_DEBUG_OBJECTS_RCU_HEAD=y" has been set as well. (see https://syzkaller.appspot.com/text?tag=KernelConfig&x=dcbf08d90aa89bca) But there were no logs related with double call_srcu(). (see https://syzkaller.appspot.com/text?tag=CrashLog&x=13e40434580000) Unfortunately we don’t yet have a simple reproducer to reliably trigger the warning. Could you please advise whether a patch for this has already landed in mainline, or suggest any additional methods we could use to further validate and test it? Thanks. Youngmin
