syzbot has found a reproducer for the following issue on: HEAD commit: 7af08140 Revert "gcov: clang: fix clang-11+ build" git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15416871d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=c0a6882014fd3d45 dashboard link: https://syzkaller.appspot.com/bug?extid=7692cea7450c97fa2a0a compiler: Debian clang version 11.0.1-2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=145c9ffed00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12de31ded00000 The issue was bisected to: commit 1cf8dfe8a661f0462925df943140e9f6d1ea5233 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Date: Sat Jul 13 09:21:25 2019 +0000 perf/core: Fix race between close() and fork() bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1523f40c600000 final oops: https://syzkaller.appspot.com/x/report.txt?x=1723f40c600000 console output: https://syzkaller.appspot.com/x/log.txt?x=1323f40c600000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7692cea7450c97fa2a0a@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 1cf8dfe8a661 ("perf/core: Fix race between close() and fork()") INFO: task syz-executor890:6628 blocked for more than 143 seconds. Not tainted 5.12.0-rc8-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor890 state:D stack:25968 pid: 6628 ppid: 8391 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4322 [inline] __schedule+0xa4d/0xf80 kernel/sched/core.c:5073 schedule+0x14b/0x200 kernel/sched/core.c:5152 perf_event_free_task+0x575/0x6a0 kernel/events/core.c:12623 copy_process+0x418f/0x57e0 kernel/fork.c:2376 kernel_clone+0x21a/0x7d0 kernel/fork.c:2500 __do_sys_clone kernel/fork.c:2617 [inline] __se_sys_clone kernel/fork.c:2601 [inline] __x64_sys_clone+0x236/0x2b0 kernel/fork.c:2601 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x44b6e9 RSP: 002b:00007fd6c1512208 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00000000004d7288 RCX: 000000000044b6e9 RDX: 9999999999999999 RSI: 0000000000000000 RDI: 0000000022086605 RBP: 00000000004d7280 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004d728c R13: 00007ffc3bab65ef R14: 00007fd6c1512300 R15: 0000000000022000 Showing all locks held in the system: 1 lock held by khungtaskd/1623: #0: ffffffff8cd10280 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 arch/x86/pci/mmconfig_64.c:151 2 locks held by systemd-journal/4819: 1 lock held by in:imklog/8079: #0: ffff8880163265f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:974 2 locks held by syz-executor890/6495: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1623 Comm: khungtaskd Not tainted 5.12.0-rc8-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x202/0x31e lib/dump_stack.c:120 nmi_cpu_backtrace+0x16c/0x190 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x191/0x2f0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0xcfb/0xd40 kernel/hung_task.c:294 kthread+0x39a/0x3c0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 6495 Comm: syz-executor890 Not tainted 5.12.0-rc8-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:155 [inline] RIP: 0010:unwind_next_frame+0x184/0x1f90 arch/x86/kernel/unwind_orc.c:443 Code: 89 7c 24 70 0f 84 1a 01 00 00 48 c7 c0 00 00 00 81 49 39 c4 0f 82 16 01 00 00 48 c7 c0 52 83 e0 89 49 39 c4 0f 83 06 01 00 00 <48> c7 c0 00 00 00 81 4c 89 e5 48 29 c5 48 c1 ed 08 48 c7 c0 e8 8d RSP: 0000:ffffc9000dd5f720 EFLAGS: 00000087 RAX: ffffffff89e08352 RBX: ffffc9000dd5f828 RCX: ffffffff9031ab03 RDX: ffffc9000dd5fc20 RSI: ffffffff814e6de0 RDI: 0000000000000001 RBP: ffffc9000dd5f815 R08: 0000000000000003 R09: ffffc9000dd5f8b0 R10: fffff52001babf08 R11: 0000000000000000 R12: ffffffff814e6ddf R13: ffffc9000dd5f7e0 R14: dffffc0000000000 R15: 1ffff92001babf02 FS: 00007fd6c1512700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000022000 CR3: 0000000034d8b000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: arch_stack_walk+0xb2/0xe0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x104/0x1e0 kernel/stacktrace.c:121 kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:427 [inline] __kasan_slab_alloc+0x8f/0xc0 mm/kasan/common.c:460 kasan_slab_alloc include/linux/kasan.h:223 [inline] slab_post_alloc_hook mm/slab.h:516 [inline] slab_alloc_node mm/slub.c:2907 [inline] slab_alloc mm/slub.c:2915 [inline] kmem_cache_alloc+0x1c3/0x350 mm/slub.c:2920 __sigqueue_alloc+0x2c2/0x490 kernel/signal.c:435 __send_signal+0x210/0xe50 kernel/signal.c:1116 force_sig_info_to_task+0x2a4/0x3f0 kernel/signal.c:1334 force_sig_fault_to_task kernel/signal.c:1673 [inline] force_sig_fault+0x11e/0x1c0 kernel/signal.c:1680 __bad_area_nosemaphore+0x390/0x570 arch/x86/mm/fault.c:840 handle_page_fault arch/x86/mm/fault.c:1475 [inline] exc_page_fault+0xa1/0x1e0 arch/x86/mm/fault.c:1531 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:577 RIP: 0033:0x22000 Code: Unable to access opcode bytes at RIP 0x21fd6. RSP: 002b:00007fd6c1512220 EFLAGS: 00010206 RAX: ffffffffffffffff RBX: 00000000004d7288 RCX: ffffffffffffffbc RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000000 RBP: 00000000004d7280 R08: 0000000000000000 R09: 00007fd6c1512300 R10: 00000000ffffffff R11: 0000000000000246 R12: 00000000004d728c R13: 00007ffc3bab65ef R14: 00007fd6c1512300 R15: 0000000000022000
