Hello, syzbot found the following issue on: HEAD commit: 4e78c578 Add linux-next specific files for 20201030 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=148969d4500000 kernel config: https://syzkaller.appspot.com/x/.config?x=83318758268dc331 dashboard link: https://syzkaller.appspot.com/bug?extid=b57abf7ee60829090495 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17e1346c500000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1388fbca500000 The issue was bisected to: commit 4d004099a668c41522242aa146a38cc4eb59cb1e Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Date: Fri Oct 2 09:04:21 2020 +0000 lockdep: Fix lockdep recursion bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1354e614500000 final oops: https://syzkaller.appspot.com/x/report.txt?x=10d4e614500000 console output: https://syzkaller.appspot.com/x/log.txt?x=1754e614500000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b57abf7ee60829090495@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 4d004099a668 ("lockdep: Fix lockdep recursion") ================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: null-ptr-deref in atomic_inc include/asm-generic/atomic-instrumented.h:240 [inline] BUG: KASAN: null-ptr-deref in mmgrab include/linux/sched/mm.h:36 [inline] BUG: KASAN: null-ptr-deref in kthread_use_mm+0x11c/0x2a0 kernel/kthread.c:1257 Write of size 4 at addr 0000000000000060 by task io_uring-sq/26191 CPU: 1 PID: 26191 Comm: io_uring-sq Not tainted 5.10.0-rc1-next-20201030-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:118 __kasan_report mm/kasan/report.c:549 [inline] kasan_report.cold+0x5/0x37 mm/kasan/report.c:562 check_memory_region_inline mm/kasan/generic.c:186 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:192 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic_inc include/asm-generic/atomic-instrumented.h:240 [inline] mmgrab include/linux/sched/mm.h:36 [inline] kthread_use_mm+0x11c/0x2a0 kernel/kthread.c:1257 __io_sq_thread_acquire_mm fs/io_uring.c:1092 [inline] __io_sq_thread_acquire_mm+0x1c4/0x220 fs/io_uring.c:1085 io_sq_thread_acquire_mm_files.isra.0+0x125/0x180 fs/io_uring.c:1104 io_init_req fs/io_uring.c:6661 [inline] io_submit_sqes+0x89d/0x25f0 fs/io_uring.c:6757 __io_sq_thread fs/io_uring.c:6904 [inline] io_sq_thread+0x462/0x1630 fs/io_uring.c:6971 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 ================================================================== Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 26191 Comm: io_uring-sq Tainted: G B 5.10.0-rc1-next-20201030-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:118 panic+0x306/0x73d kernel/panic.c:231 end_report+0x58/0x5e mm/kasan/report.c:106 __kasan_report mm/kasan/report.c:552 [inline] kasan_report.cold+0xd/0x37 mm/kasan/report.c:562 check_memory_region_inline mm/kasan/generic.c:186 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:192 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic_inc include/asm-generic/atomic-instrumented.h:240 [inline] mmgrab include/linux/sched/mm.h:36 [inline] kthread_use_mm+0x11c/0x2a0 kernel/kthread.c:1257 __io_sq_thread_acquire_mm fs/io_uring.c:1092 [inline] __io_sq_thread_acquire_mm+0x1c4/0x220 fs/io_uring.c:1085 io_sq_thread_acquire_mm_files.isra.0+0x125/0x180 fs/io_uring.c:1104 io_init_req fs/io_uring.c:6661 [inline] io_submit_sqes+0x89d/0x25f0 fs/io_uring.c:6757 __io_sq_thread fs/io_uring.c:6904 [inline] io_sq_thread+0x462/0x1630 fs/io_uring.c:6971 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Kernel Offset: disabled Rebooting in 86400 seconds.. --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
