syzbot has found a reproducer for the following issue on: HEAD commit: 99c710c4 Merge tag 'platform-drivers-x86-v5.10-2' of git:/.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1780c563500000 kernel config: https://syzkaller.appspot.com/x/.config?x=6d1e98d0b97781e4 dashboard link: https://syzkaller.appspot.com/bug?extid=dd74984384afdb86e904 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11e6161d500000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1651b32d500000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+dd74984384afdb86e904@xxxxxxxxxxxxxxxxxxxxxxxxx ------------[ cut here ]------------ WARNING: CPU: 1 PID: 9857 at include/linux/cpumask.h:137 rcu_read_unlock include/linux/rcupdate.h:696 [inline] WARNING: CPU: 1 PID: 9857 at include/linux/cpumask.h:137 ttwu_stat kernel/sched/core.c:2441 [inline] WARNING: CPU: 1 PID: 9857 at include/linux/cpumask.h:137 try_to_wake_up+0xef6/0x1330 kernel/sched/core.c:2984 Modules linked in: CPU: 1 PID: 9857 Comm: io_wq_manager Not tainted 5.10.0-rc5-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 RIP: 0010:cpu_max_bits_warn include/linux/cpumask.h:137 [inline] RIP: 0010:cpumask_check include/linux/cpumask.h:144 [inline] RIP: 0010:cpumask_check include/linux/cpumask.h:142 [inline] RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:367 [inline] RIP: 0010:is_cpu_allowed kernel/sched/core.c:1705 [inline] RIP: 0010:select_task_rq kernel/sched/core.c:2370 [inline] RIP: 0010:try_to_wake_up+0xef6/0x1330 kernel/sched/core.c:2964 Code: 80 3d 93 2a 8c 0b 00 0f 84 f1 00 00 00 e8 82 80 10 00 48 c7 c6 d9 6d 4c 81 48 c7 c7 e0 77 33 8b e8 0f b7 09 00 e9 15 f9 ff ff <0f> 0b e9 65 f4 ff ff 4c 89 ff 48 89 4c 24 08 e8 b6 51 ff ff 48 8b RSP: 0018:ffffc900009c7d50 EFLAGS: 00010002 RAX: dffffc0000000000 RBX: 1ffff92000138faf RCX: ffff88804825c438 RDX: 1ffff1100904b886 RSI: ffffffff83b63c9b RDI: 0000000000000006 RBP: ffff88804825c0c0 R08: ffff88804825c0d0 R09: ffffffff8cecc98f R10: 0000000000000040 R11: 0000000000000000 R12: 0000000000000202 R13: ffff88804825c8f8 R14: 0000000000000008 R15: ffff88804825c430 FS: 0000000000000000(0000) GS:ffff88802cb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000560a8007e384 CR3: 00000000133db000 CR4: 0000000000350ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: create_io_worker+0x590/0x8d0 fs/io-wq.c:720 io_wq_manager+0x16b/0xb80 fs/io-wq.c:785 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
