INFO: task syz-executor:5836 blocked for more than 143 seconds. Not tainted 6.12.0-rc5-syzkaller-00063-g0fc810ae3ae1 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:20992 pid:5836 tgid:5836 ppid:1 flags:0x00004006 Call Trace: context_switch kernel/sched/core.c:5328 [inline] __schedule+0x185a/0x4b70 kernel/sched/core.c:6690 __schedule_loop kernel/sched/core.c:6767 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6782 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6839 rwsem_down_write_slowpath+0xeee/0x13b0 kernel/locking/rwsem.c:1176 __down_write_common kernel/locking/rwsem.c:1304 [inline] __down_write kernel/locking/rwsem.c:1313 [inline] down_write+0x1d7/0x220 kernel/locking/rwsem.c:1578 __bch2_fs_stop+0xfd/0x5c0 fs/bcachefs/super.c:619 generic_shutdown_super+0x139/0x2d0 fs/super.c:642 bch2_kill_sb+0x41/0x50 fs/bcachefs/fs.c:2278 deactivate_locked_super+0xc4/0x130 fs/super.c:473 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1373 task_work_run+0x24f/0x310 kernel/task_work.c:239 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9b1a17fa47 RSP: 002b:00007fff5bbc5358 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f9b1a17fa47 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff5bbc5410 RBP: 00007fff5bbc5410 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fff5bbc6490 R13: 00007f9b1a1f11cc R14: 00000000000104da R15: 00007fff5bbc64d0 INFO: task kworker/0:4:5870 blocked for more than 144 seconds. Not tainted 6.12.0-rc5-syzkaller-00063-g0fc810ae3ae1 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:4 state:D stack:24184 pid:5870 tgid:5870 ppid:2 flags:0x00004000 Workqueue: events_long bch2_fs_read_only_work Call Trace: context_switch kernel/sched/core.c:5328 [inline] __schedule+0x185a/0x4b70 kernel/sched/core.c:6690 __schedule_loop kernel/sched/core.c:6767 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6782 schedule_timeout+0xb0/0x310 kernel/time/timer.c:2591 do_wait_for_common kernel/sched/completion.c:95 [inline] __wait_for_common kernel/sched/completion.c:116 [inline] wait_for_common kernel/sched/completion.c:127 [inline] wait_for_completion+0x355/0x620 kernel/sched/completion.c:148 kthread_stop+0x19e/0x640 kernel/kthread.c:712 bch2_copygc_stop+0x4f/0x150 fs/bcachefs/movinggc.c:411 __bch2_fs_read_only+0x47/0x430 fs/bcachefs/super.c:265 bch2_fs_read_only+0xb57/0x1200 fs/bcachefs/super.c:355 bch2_fs_read_only_work+0x2d/0x40 fs/bcachefs/super.c:393 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 INFO: task kworker/1:4:5903 blocked for more than 144 seconds. Not tainted 6.12.0-rc5-syzkaller-00063-g0fc810ae3ae1 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:4 state:D stack:17008 pid:5903 tgid:5903 ppid:2 flags:0x00004000 Workqueue: bcachefs_write_ref bch2_delete_dead_snapshots_work (bcachefs-delete-dead-snapshots/) Call Trace: context_switch kernel/sched/core.c:5328 [inline] __schedule+0x185a/0x4b70 kernel/sched/core.c:6690 __schedule_loop kernel/sched/core.c:6767 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6782 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2615 __closure_sync_timeout+0x2d8/0x450 lib/closure.c:217 closure_sync_timeout include/linux/closure.h:206 [inline] __bch2_wait_on_allocator+0x11a/0x250 fs/bcachefs/alloc_foreground.c:1799 bch2_wait_on_allocator fs/bcachefs/alloc_foreground.h:239 [inline] bch2_btree_update_start+0x11a2/0x14e0 fs/bcachefs/btree_update_interior.c:1274 bch2_btree_split_leaf+0x123/0x840 fs/bcachefs/btree_update_interior.c:1850 bch2_trans_commit_error+0x212/0x1390 fs/bcachefs/btree_trans_commit.c:942 __bch2_trans_commit+0x7ead/0x93c0 fs/bcachefs/btree_trans_commit.c:1140 bch2_trans_commit fs/bcachefs/btree_update.h:184 [inline] bch2_delete_dead_snapshots+0x19b6/0x5ae0 fs/bcachefs/snapshot.c:1643 bch2_delete_dead_snapshots_work+0x34/0x40 fs/bcachefs/snapshot.c:1718 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 INFO: task bch-copygc/loop:5938 blocked for more than 145 seconds. Not tainted 6.12.0-rc5-syzkaller-00063-g0fc810ae3ae1 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:bch-copygc/loop state:D stack:17168 pid:5938 tgid:5938 ppid:2 flags:0x00024000 Call Trace: context_switch kernel/sched/core.c:5328 [inline] __schedule+0x185a/0x4b70 kernel/sched/core.c:6690 __schedule_loop kernel/sched/core.c:6767 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6782 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2615 __closure_sync_timeout+0x2d8/0x450 lib/closure.c:217 closure_sync_timeout include/linux/closure.h:206 [inline] __bch2_wait_on_allocator+0x11a/0x250 fs/bcachefs/alloc_foreground.c:1799 bch2_wait_on_allocator fs/bcachefs/alloc_foreground.h:239 [inline] __bch2_write+0x562a/0x5dd0 fs/bcachefs/io_write.c:1504 bch2_write+0x9b5/0x1760 fs/bcachefs/io_write.c:1634 closure_queue include/linux/closure.h:270 [inline] closure_call include/linux/closure.h:432 [inline] bch2_data_update_read_done+0x22e/0x330 fs/bcachefs/data_update.c:424 move_write fs/bcachefs/move.c:133 [inline] bch2_moving_ctxt_do_pending_writes+0x44c/0x8d0 fs/bcachefs/move.c:164 move_buckets_wait+0x182/0x1290 fs/bcachefs/movinggc.c:120 bch2_copygc_thread+0x83f/0xc20 fs/bcachefs/movinggc.c:392 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Showing all locks held in the system: 3 locks held by kworker/u8:0/11: #0: ffff888030a1a148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff888030a1a148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310 #1: ffffc90000107d00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc90000107d00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310 #2: ffffffff8fcc0e88 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x19/0x30 net/ipv6/addrconf.c:4736 3 locks held by kworker/u8:1/12: #0: ffff8880b863ea58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:598 #1: ffff8880b8628948 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x41d/0x7a0 kernel/sched/psi.c:987 #2: ffff8880b862a718 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x112/0x240 kernel/time/timer.c:1051 1 lock held by khungtaskd/30: #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6720 5 locks held by kworker/u8:5/1131: #0: ffff88801baeb148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88801baeb148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310 #1: ffffc90003dc7d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc90003dc7d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310 #2: ffffffff8fcb4390 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x16a/0xcc0 net/core/net_namespace.c:580 #3: ffffffff8fcc0e88 (rtnl_mutex){+.+.}-{3:3}, at: cleanup_net+0x6af/0xcc0 net/core/net_namespace.c:616 #4: ffffffff8e93d338 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:329 [inline] #4: ffffffff8e93d338 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x451/0x830 kernel/rcu/tree_exp.h:976 1 lock held by udevd/5202: #0: ffff8880b863ea58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:598 1 lock held by dhcpcd/5496: #0: ffffffff8fcc0e88 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:79 [inline] #0: ffffffff8fcc0e88 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x6e6/0xcf0 net/core/rtnetlink.c:6672 2 locks held by getty/5579: #0: ffff8881489260a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc900032532f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211 2 locks held by syz-executor/5836: #0: ffff888031c380e0 (&type->s_umount_key#59){++++}-{3:3}, at: __super_lock fs/super.c:56 [inline] #0: ffff888031c380e0 (&type->s_umount_key#59){++++}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline] #0: ffff888031c380e0 (&type->s_umount_key#59){++++}-{3:3}, at: deactivate_super+0xb5/0xf0 fs/super.c:505 #1: ffff88804f400278 (&c->state_lock){+.+.}-{3:3}, at: __bch2_fs_stop+0xfd/0x5c0 fs/bcachefs/super.c:619 3 locks held by kworker/0:4/5870: #0: ffff88801ac81148 ((wq_completion)events_long){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88801ac81148 ((wq_completion)events_long){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310 #1: ffffc90003ce7d00 ((work_completion)(&c->read_only_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc90003ce7d00 ((work_completion)(&c->read_only_work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310 #2: ffff88804f400278 (&c->state_lock){+.+.}-{3:3}, at: bch2_fs_read_only_work+0x25/0x40 fs/bcachefs/super.c:392 4 locks held by kworker/1:4/5903: #0: ffff88802dd51148 ((wq_completion)bcachefs_write_ref){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88802dd51148 ((wq_completion)bcachefs_write_ref){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310 #1: ffffc90004077d00 ((work_completion)(&c->snapshot_delete_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc90004077d00 ((work_completion)(&c->snapshot_delete_work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310 #2: ffff88804f404398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:151 [inline] #2: ffff88804f404398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:250 [inline] #2: ffff88804f404398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: bch2_trans_srcu_lock+0x97/0x1a0 fs/bcachefs/btree_iter.c:3040 #3: ffff88804f4266d0 (&c->gc_lock){.+.+}-{3:3}, at: bch2_btree_update_start+0x682/0x14e0 fs/bcachefs/btree_update_interior.c:1202 3 locks held by kworker/1:7/5919: #0: ffff88801ac80948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88801ac80948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310 #1: ffffc90004177d00 (deferred_process_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc90004177d00 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310 #2: ffffffff8fcc0e88 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104 3 locks held by kworker/u8:8/6129: #0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310 #1: ffffc900043c7d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc900043c7d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310 #2: ffffffff8fcc0e88 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:276 7 locks held by syz-executor/8297: #0: ffff888023c6c420 (sb_writers#8){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2931 [inline] #0: ffff888023c6c420 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x225/0xd30 fs/read_write.c:679 #1: ffff88807a61d488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1ea/0x500 fs/kernfs/file.c:325 #2: ffff888143f7e4b8 (kn->active#50){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x20e/0x500 fs/kernfs/file.c:326 #3: ffffffff8f55ed88 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: new_device_store+0x1b4/0x890 drivers/net/netdevsim/bus.c:166 #4: ffff8880580ec0e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline] #4: ffff8880580ec0e8 (&dev->mutex){....}-{3:3}, at: __device_attach+0x8e/0x520 drivers/base/dd.c:1005 #5: ffff8880580ed250 (&devlink->lock_key#14){+.+.}-{3:3}, at: nsim_drv_probe+0xcb/0xb80 drivers/net/netdevsim/dev.c:1537 #6: ffffffff8fcc0e88 ( rtnl_mutex ){+.+.}-{3:3} , at: nsim_init_netdevsim drivers/net/netdevsim/netdev.c:678 [inline] , at: nsim_create+0x408/0x890 drivers/net/netdevsim/netdev.c:750 1 lock held by syz-executor/8372: #0: ffffffff8fcc0e88 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:79 [inline] #0: ffffffff8fcc0e88 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x6e6/0xcf0 net/core/rtnetlink.c:6672 1 lock held by syz.4.285/8587: #0: ffff888031c380e0 (&type->s_umount_key#59){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline] #0: ffff888031c380e0 (&type->s_umount_key#59){++++}-{3:3}, at: super_lock+0x27c/0x400 fs/super.c:120 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.12.0-rc5-syzkaller-00063-g0fc810ae3ae1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline] watchdog+0xff4/0x1040 kernel/hung_task.c:379 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 61 Comm: kworker/u8:4 Not tainted 6.12.0-rc5-syzkaller-00063-g0fc810ae3ae1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events_unbound cfg80211_wiphy_work RIP: 0010:task_wait_context kernel/locking/lockdep.c:4754 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4847 [inline] RIP: 0010:__lock_acquire+0x7cc/0x2050 kernel/locking/lockdep.c:5152 Code: 00 00 00 fc ff df eb aa 48 c7 c7 c0 44 80 8e 48 89 de e8 d7 c8 7c 03 48 8b 34 24 48 ba 00 00 00 00 00 fc ff df e9 65 ff ff ff <65> 8b 05 c9 31 92 7e b3 02 85 c0 75 21 48 8b 44 24 58 0f b6 04 10 RSP: 0018:ffffc900015c7450 EFLAGS: 00000096 RAX: 0000000000000000 RBX: 00000000000800c0 RCX: 0000000000000002 RDX: dffffc0000000000 RSI: ffff888021a864e0 RDI: 000000000000000f RBP: 00000000ffffffff R08: ffffffff94296807 R09: 1ffffffff2852d00 R10: dffffc0000000000 R11: fffffbfff2852d01 R12: 0000000000000000 R13: ffff888021a864d8 R14: 1ffff11004350caf R15: ffff888021a86578 FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9c26909178 CR3: 0000000012532000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162 debug_object_assert_init+0x164/0x440 lib/debugobjects.c:897 debug_timer_assert_init kernel/time/timer.c:846 [inline] debug_assert_init kernel/time/timer.c:891 [inline] __mod_timer+0x10d/0xeb0 kernel/time/timer.c:1072 ieee80211_sta_merge_ibss net/mac80211/ibss.c:1271 [inline] ieee80211_ibss_work+0x4f0/0x14c0 net/mac80211/ibss.c:1671 cfg80211_wiphy_work+0x2db/0x490 net/wireless/core.c:440 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244