INFO: task syz-executor.1:31558 blocked for more than 143 seconds. Not tainted 6.3.0-rc5-syzkaller-00005-g148341f0a2f5 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.1 state:D stack:27560 pid:31558 ppid:5090 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5307 [inline] __schedule+0x173b/0x4630 kernel/sched/core.c:6625 schedule+0xc3/0x180 kernel/sched/core.c:6701 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6760 __mutex_lock_common+0xe33/0x2530 kernel/locking/mutex.c:679 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799 blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 blkdev_open+0x132/0x2f0 block/fops.c:493 do_dentry_open+0x7f9/0x10f0 fs/open.c:920 do_open fs/namei.c:3560 [inline] path_openat+0x27b3/0x3170 fs/namei.c:3715 do_filp_open+0x234/0x490 fs/namei.c:3742 do_sys_openat2+0x13f/0x500 fs/open.c:1348 do_sys_open fs/open.c:1364 [inline] __do_sys_openat fs/open.c:1380 [inline] __se_sys_openat fs/open.c:1375 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1375 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fa73fc8c169 RSP: 002b:00007fa740909168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fa73fdabf80 RCX: 00007fa73fc8c169 RDX: 0000000000000000 RSI: 0000000020001680 RDI: ffffffffffffff9c RBP: 00007fa73fce7ca1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffdd60ab01f R14: 00007fa740909300 R15: 0000000000022000 INFO: task syz-executor.0:31560 blocked for more than 144 seconds. Not tainted 6.3.0-rc5-syzkaller-00005-g148341f0a2f5 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.0 state:D stack:27560 pid:31560 ppid:5089 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5307 [inline] __schedule+0x173b/0x4630 kernel/sched/core.c:6625 schedule+0xc3/0x180 kernel/sched/core.c:6701 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6760 __mutex_lock_common+0xe33/0x2530 kernel/locking/mutex.c:679 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799 blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 blkdev_open+0x132/0x2f0 block/fops.c:493 do_dentry_open+0x7f9/0x10f0 fs/open.c:920 do_open fs/namei.c:3560 [inline] path_openat+0x27b3/0x3170 fs/namei.c:3715 do_filp_open+0x234/0x490 fs/namei.c:3742 do_sys_openat2+0x13f/0x500 fs/open.c:1348 do_sys_open fs/open.c:1364 [inline] __do_sys_openat fs/open.c:1380 [inline] __se_sys_openat fs/open.c:1375 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1375 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7ff34de8c169 RSP: 002b:00007ff34c9fe168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007ff34dfabf80 RCX: 00007ff34de8c169 RDX: 0000000000000000 RSI: 0000000020000040 RDI: ffffffffffffff9c RBP: 00007ff34dee7ca1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff7f87cc7f R14: 00007ff34c9fe300 R15: 0000000000022000 INFO: task syz-executor.2:31559 blocked for more than 145 seconds. Not tainted 6.3.0-rc5-syzkaller-00005-g148341f0a2f5 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.2 state:D stack:27560 pid:31559 ppid:5109 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5307 [inline] __schedule+0x173b/0x4630 kernel/sched/core.c:6625 schedule+0xc3/0x180 kernel/sched/core.c:6701 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6760 __mutex_lock_common+0xe33/0x2530 kernel/locking/mutex.c:679 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799 blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 blkdev_open+0x132/0x2f0 block/fops.c:493 do_dentry_open+0x7f9/0x10f0 fs/open.c:920 do_open fs/namei.c:3560 [inline] path_openat+0x27b3/0x3170 fs/namei.c:3715 do_filp_open+0x234/0x490 fs/namei.c:3742 do_sys_openat2+0x13f/0x500 fs/open.c:1348 do_sys_open fs/open.c:1364 [inline] __do_sys_openat fs/open.c:1380 [inline] __se_sys_openat fs/open.c:1375 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1375 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f730268c169 RSP: 002b:00007f73033d4168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f73027abf80 RCX: 00007f730268c169 RDX: 0000000000000000 RSI: 0000000020001680 RDI: ffffffffffffff9c RBP: 00007f73026e7ca1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fffa315061f R14: 00007f73033d4300 R15: 0000000000022000 INFO: task syz-executor.3:31592 blocked for more than 146 seconds. Not tainted 6.3.0-rc5-syzkaller-00005-g148341f0a2f5 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.3 state:D stack:27320 pid:31592 ppid:31572 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5307 [inline] __schedule+0x173b/0x4630 kernel/sched/core.c:6625 schedule+0xc3/0x180 kernel/sched/core.c:6701 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6760 __mutex_lock_common+0xe33/0x2530 kernel/locking/mutex.c:679 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799 blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 blkdev_open+0x132/0x2f0 block/fops.c:493 do_dentry_open+0x7f9/0x10f0 fs/open.c:920 do_open fs/namei.c:3560 [inline] path_openat+0x27b3/0x3170 fs/namei.c:3715 do_filp_open+0x234/0x490 fs/namei.c:3742 do_sys_openat2+0x13f/0x500 fs/open.c:1348 do_sys_open fs/open.c:1364 [inline] __do_sys_openat fs/open.c:1380 [inline] __se_sys_openat fs/open.c:1375 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1375 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f225d28c169 RSP: 002b:00007f225e080168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f225d3abf80 RCX: 00007f225d28c169 RDX: 0000000000000000 RSI: 0000000020000040 RDI: ffffffffffffff9c RBP: 00007f225d2e7ca1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff03f8f1ff R14: 00007f225e080300 R15: 0000000000022000 Showing all locks held in the system: 1 lock held by rcu_tasks_kthre/12: #0: ffffffff8cf25530 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:510 1 lock held by rcu_tasks_trace/13: #0: ffffffff8cf25d30 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:510 1 lock held by khungtaskd/27: #0: ffffffff8cf25360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 2 locks held by kworker/1:1/33: #0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x77e/0x10e0 kernel/workqueue.c:2363 #1: ffffc90000a9fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7c8/0x10e0 kernel/workqueue.c:2365 2 locks held by getty/4747: #0: ffff8880288ab098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:244 #1: ffffc900015802f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6ab/0x1db0 drivers/tty/n_tty.c:2177 3 locks held by kworker/0:4/5154: #0: ffff888149fbcd38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x77e/0x10e0 kernel/workqueue.c:2363 #1: ffffc9000489fd20 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7c8/0x10e0 kernel/workqueue.c:2365 #2: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x16b0 net/ipv6/addrconf.c:4088 3 locks held by kworker/0:6/5185: #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x77e/0x10e0 kernel/workqueue.c:2363 #1: ffffc900048efd20 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7c8/0x10e0 kernel/workqueue.c:2365 #2: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:277 2 locks held by kworker/u4:10/21516: 3 locks held by kworker/0:0/27927: #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x77e/0x10e0 kernel/workqueue.c:2363 #1: ffffc900048afd20 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x7c8/0x10e0 kernel/workqueue.c:2365 #2: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:75 1 lock held by syz-executor.4/31396: 1 lock held by syz-executor.3/31460: 3 locks held by kworker/1:4/31484: #0: ffff888149fbcd38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x77e/0x10e0 kernel/workqueue.c:2363 #1: ffffc900032efd20 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7c8/0x10e0 kernel/workqueue.c:2365 #2: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x16b0 net/ipv6/addrconf.c:4088 1 lock held by syz-executor.4/31551: 1 lock held by syz-executor.1/31558: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.0/31560: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.2/31559: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.3/31592: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.4/31707: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.4/31708: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.3/31715: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.0/31721: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.2/31726: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.1/31731: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.1/31732: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by syz-executor.4/31760: #0: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:75 [inline] #0: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ce/0xf40 net/core/rtnetlink.c:6171 1 lock held by syz-executor.2/31770: #0: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:75 [inline] #0: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ce/0xf40 net/core/rtnetlink.c:6171 8 locks held by syz-executor.1/31784: #0: ffff88802c82a460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x26d/0xbb0 fs/read_write.c:580 #1: ffff8880b14d8888 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1eb/0x4f0 fs/kernfs/file.c:325 #2: ffff8880212d03a8 (kn->active#51){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x20f/0x4f0 fs/kernfs/file.c:326 #3: ffffffff8d9fe628 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: del_device_store+0xfc/0x480 drivers/net/netdevsim/bus.c:209 #4: ffff888076f5c0e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:832 [inline] #4: ffff888076f5c0e8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1063 [inline] #4: ffff888076f5c0e8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xce/0x7a0 drivers/base/dd.c:1260 #5: ffff888076f5e250 (&devlink->lock_key#14){+.+.}-{3:3}, at: nsim_drv_remove+0x50/0x160 drivers/net/netdevsim/dev.c:1675 #6: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x3e/0x150 drivers/net/netdevsim/netdev.c:374 #7: ffffffff8cf2a838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:325 [inline] #7: ffffffff8cf2a838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x46c/0x890 kernel/rcu/tree_exp.h:989 1 lock held by syz-executor.0/31787: #0: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:75 [inline] #0: ffffffff8e086aa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ce/0xf40 net/core/rtnetlink.c:6171 1 lock held by syz-executor.3/31819: #0: ffff88801ecee4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa30 block/bdev.c:735 1 lock held by dhcpcd/31843: #0: ffff8880774ea610 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline] #0: ffff8880774ea610 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: __sock_release net/socket.c:652 [inline] #0: ffff8880774ea610 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: sock_close+0x9c/0x230 net/socket.c:1395 2 locks held by dhcpcd/31844: #0: ffff8880a98e2130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1697 [inline] #0: ffff8880a98e2130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2a/0xbd0 net/packet/af_packet.c:3193 #1: ffffffff8cf2a838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:325 [inline] #1: ffffffff8cf2a838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x46c/0x890 kernel/rcu/tree_exp.h:989 1 lock held by dhcpcd/31845: #0: ffff888039b76130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1697 [inline] #0: ffff888039b76130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2a/0xbd0 net/packet/af_packet.c:3193 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 27 Comm: khungtaskd Not tainted 6.3.0-rc5-syzkaller-00005-g148341f0a2f5 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 nmi_cpu_backtrace+0x498/0x4d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x187/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline] watchdog+0xec2/0xf00 kernel/hung_task.c:379 kthread+0x270/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 11 Comm: kworker/u4:1 Not tainted 6.3.0-rc5-syzkaller-00005-g148341f0a2f5 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 Workqueue: phy17 ieee80211_iface_work RIP: 0010:hlock_class kernel/locking/lockdep.c:228 [inline] RIP: 0010:__lock_acquire+0xf7f/0x1f80 kernel/locking/lockdep.c:5052 Code: 00 8b 1b 81 e3 ff 1f 00 00 48 89 d8 48 c1 e8 06 48 8d 3c c5 c0 b1 2d 90 be 08 00 00 00 e8 e9 f6 75 00 48 0f a3 1d b1 9d c3 0e <0f> 83 bb 01 00 00 48 8d 04 5b 48 c1 e0 06 48 8d 98 c0 10 fd 8f 48 RSP: 0000:ffffc90000107480 EFLAGS: 00000057 RAX: 0000000000000001 RBX: 000000000000033d RCX: ffffffff816a1407 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff902db220 RBP: b5598d9acc86daa5 R08: dffffc0000000000 R09: fffffbfff205b645 R10: 0000000000000000 R11: dffffc0000000001 R12: ffff8880167ec4b0 R13: ffff8880167eba80 R14: 0000000000000000 R15: 1ffff11002cfd8aa FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005585e2f20600 CR3: 000000000cd30000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1e1/0x520 kernel/locking/lockdep.c:5669 rcu_lock_acquire+0x2e/0x40 include/linux/rcupdate.h:327 rcu_read_lock include/linux/rcupdate.h:773 [inline] ieee80211_bss_info_update+0x406/0xf00 net/mac80211/scan.c:177 ieee80211_rx_bss_info net/mac80211/ibss.c:1120 [inline] ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1609 [inline] ieee80211_ibss_rx_queued_mgmt+0x192f/0x2cf0 net/mac80211/ibss.c:1638 ieee80211_iface_process_skb net/mac80211/iface.c:1583 [inline] ieee80211_iface_work+0x7bd/0xd00 net/mac80211/iface.c:1637 process_one_work+0x8a0/0x10e0 kernel/workqueue.c:2390 worker_thread+0xa63/0x1210 kernel/workqueue.c:2537 kthread+0x270/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308