================================================================== BUG: KCSAN: data-race in userfaultfd_ioctl / userfaultfd_ioctl write to 0xffff888124beeff0 of 4 bytes by task 16432 on cpu 0: userfaultfd_api fs/userfaultfd.c:1868 [inline] userfaultfd_ioctl+0x718/0x2530 fs/userfaultfd.c:1892 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 read to 0xffff888124beeff0 of 4 bytes by task 16440 on cpu 1: userfaultfd_ioctl+0x8f/0x2530 fs/userfaultfd.c:1887 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 16440 Comm: syz-executor.1 Not tainted 5.9.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ================================================================== Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 16440 Comm: syz-executor.1 Not tainted 5.9.0-rc4-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+0x10f/0x19d lib/dump_stack.c:118 panic+0x207/0x64a kernel/panic.c:231 kcsan_report+0x684/0x690 kernel/kcsan/report.c:630 kcsan_setup_watchpoint+0x41e/0x4a0 kernel/kcsan/core.c:540 userfaultfd_ioctl+0x8f/0x2530 fs/userfaultfd.c:1887 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f02954a4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000001a380 RCX: 000000000045d5b9 RDX: 00000000200000c0 RSI: 00000000c020aa00 RDI: 0000000000000003 RBP: 000000000118d020 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cfec R13: 00007ffddce6439f R14: 00007f02954a59c0 R15: 000000000118cfec Kernel Offset: disabled Rebooting in 86400 seconds..