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Wed, 28 Apr 2021 07:40:31 -0700 (PDT) Date: Wed, 28 Apr 2021 07:40:31 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000053287805c1095c9d@google.com> Subject: [syzbot] WARNING in percpu_ref_switch_to_atomic_rcu (2) From: syzbot To: bp@alien8.de, dwmw@amazon.co.uk, hpa@zytor.com, linux-kernel@vger.kernel.org, luto@kernel.org, mingo@redhat.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, x86@kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, syzbot found the following issue on: HEAD commit: 57fa2369 Merge tag 'cfi-v5.13-rc1' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=173e8725d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=c37352b2923ef305 dashboard link: https://syzkaller.appspot.com/bug?extid=842c825a3ade3fb904bf syz repro: https://syzkaller.appspot.com/x/repro.syz?x=135f0c7dd00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+842c825a3ade3fb904bf@syzkaller.appspotmail.com ------------[ cut here ]------------ percpu ref (free_ioctx_reqs) <= 0 (0) after switching to atomic WARNING: CPU: 0 PID: 9966 at lib/percpu-refcount.c:196 percpu_ref_switch_to_atomic_rcu+0x3e4/0x4a0 lib/percpu-refcount.c:196 Modules linked in: CPU: 0 PID: 9966 Comm: kworker/u4:4 Not tainted 5.12.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound call_usermodehelper_exec_work RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x3e4/0x4a0 lib/percpu-refcount.c:196 Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 ba 00 00 00 48 8b 44 24 08 4c 89 e2 48 c7 c7 80 05 c2 89 48 8b 70 e8 e8 cb 7c fb 04 <0f> 0b e9 3b ff ff ff 48 c7 c7 a4 27 c6 8d e8 39 a9 ee fd e9 19 fd RSP: 0018:ffffc90000007e28 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff88803c80b880 RSI: ffffffff815c3fc5 RDI: fffff52000000fb7 RBP: ffff888027181980 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815bcd5e R11: 0000000000000000 R12: 0000000000000000 R13: 0000607f46081cc0 R14: 0000000000000007 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000300 CR3: 0000000012084000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_do_batch kernel/rcu/tree.c:2559 [inline] rcu_core+0x74a/0x12f0 kernel/rcu/tree.c:2794 __do_softirq+0x29b/0x9f6 kernel/softirq.c:559 invoke_softirq kernel/softirq.c:433 [inline] __irq_exit_rcu kernel/softirq.c:637 [inline] irq_exit_rcu+0x134/0x200 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632 RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:163 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:197 Code: f0 4d 89 03 e9 f2 fc ff ff b9 ff ff ff ff ba 08 00 00 00 4d 8b 03 48 0f bd ca 49 8b 45 00 48 63 c9 e9 64 ff ff ff 0f 1f 40 00 <65> 8b 05 29 07 8e 7e 89 c1 48 8b 34 24 81 e1 00 01 00 00 65 48 8b RSP: 0018:ffffc9000b2f78d0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000200 RCX: 0000000000000000 RDX: ffff88803c80b880 RSI: ffffffff816465bf RDI: 0000000000000003 RBP: 0000000000044664 R08: 0000000000000000 R09: ffffffff901948b7 R10: ffffffff816465b5 R11: 0000000000000000 R12: 0000000000000000 R13: dffffc0000000000 R14: ffffffff8bf92b90 R15: 0000000000002192 __seqprop_raw_spinlock_sequence include/linux/seqlock.h:276 [inline] timekeeping_get_delta kernel/time/timekeeping.c:252 [inline] timekeeping_get_ns kernel/time/timekeeping.c:386 [inline] ktime_get_with_offset+0x1f5/0x500 kernel/time/timekeeping.c:872 ktime_get_boottime include/linux/timekeeping.h:94 [inline] ktime_get_boottime_ns include/linux/timekeeping.h:163 [inline] copy_process+0x350f/0x71a0 kernel/fork.c:2226 kernel_clone+0xe7/0xab0 kernel/fork.c:2500 kernel_thread+0xb5/0xf0 kernel/fork.c:2552 call_usermodehelper_exec_work kernel/umh.c:172 [inline] call_usermodehelper_exec_work+0xcc/0x180 kernel/umh.c:158 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 --- 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@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches