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INFO: rcu detected stall in sys_readlink

Status: upstream: reported on 2024/07/31 14:16
Reported-by: syzbot+add64c6d165305e327c7@syzkaller.appspotmail.com
First crash: 47d, last: 47d
▶ ▼ Similar bugs (7)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_readlink (2) kernel 3 614d 673d 0/28 auto-obsoleted due to no activity on 2023/04/24 08:02
linux-5.15 INFO: rcu detected stall in sys_readlink 1 383d 383d 0/3 auto-obsoleted due to no activity on 2023/12/08 09:32
upstream INFO: rcu detected stall in sys_readlink fs 1 877d 877d 0/28 auto-closed as invalid on 2022/07/22 05:22
linux-5.15 INFO: rcu detected stall in sys_readlink (2) 3 47d 72d 0/3 upstream: reported on 2024/07/05 21:29
upstream INFO: rcu detected stall in sys_readlink (4) fs 2 288d 291d 0/28 auto-obsoleted due to no activity on 2024/03/02 18:22
upstream INFO: rcu detected stall in sys_readlink (3) bpf fs 2 489d 496d 0/28 auto-obsoleted due to no activity on 2023/08/14 04:05
android-5-15 BUG: soft lockup in sys_readlink 2 98d 157d 0/2 auto-obsoleted due to no activity on 2024/09/08 11:06

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P102/1:b..l P3093/1:b..l
	(detected by 0, t=10502 jiffies, g=14293, q=407 ncpus=2)
task:udevd           state:R  running task     stack:22600 pid:3093  ppid:1      flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6873
 irqentry_exit+0x53/0x80 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:653
RIP: 0010:preempt_count_add+0x2/0x180 kernel/sched/core.c:5700
Code: 0c 24 80 e1 07 80 c1 03 38 c1 7c 97 48 8b 3c 24 e8 e3 c1 83 00 eb 8c e9 f2 fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 66 90 41 57 <41> 56 53 89 fb 48 c7 c0 60 11 f3 91 48 c1 e8 03 49 bf 00 00 00 00
RSP: 0018:ffffc9000310f958 EFLAGS: 00000293
RAX: ffffffff84354c5a RBX: ffff8880238cb810 RCX: ffff88807d82d940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff81f551ce R09: fffff52000621f86
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000621f85
R13: ffffc9000310fc20 R14: ffff8880238cb810 R15: dffffc0000000000
 __raw_spin_lock include/linux/spinlock_api_smp.h:132 [inline]
 _raw_spin_lock+0xe/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 lockref_get_not_dead+0x22/0xb0 lib/lockref.c:184
 __legitimize_path fs/namei.c:708 [inline]
 legitimize_path fs/namei.c:718 [inline]
 try_to_unlazy+0x12c/0x5b0 fs/namei.c:779
 may_lookup fs/namei.c:1717 [inline]
 link_path_walk+0x2a0/0xee0 fs/namei.c:2267
 path_lookupat+0xa9/0x450 fs/namei.c:2478
 filename_lookup+0x251/0x600 fs/namei.c:2508
 user_path_at_empty+0x3e/0x60 fs/namei.c:2907
 do_readlinkat+0x114/0x3a0 fs/stat.c:468
 __do_sys_readlink fs/stat.c:501 [inline]
 __se_sys_readlink fs/stat.c:498 [inline]
 __x64_sys_readlink+0x7b/0x90 fs/stat.c:498
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc761f17d47
RSP: 002b:00007fff93fa6e58 EFLAGS: 00000206 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc761f17d47
RDX: 0000000000000400 RSI: 00007fff93fa7268 RDI: 00007fff93fa6e68
RBP: 00007fff93fa76a8 R08: 00005588979161fd R09: 0000000000000000
R10: 0000000000000010 R11: 0000000000000206 R12: 0000000000000200
R13: 00007fff93fa7268 R14: 00007fff93fa6e68 R15: 0000000000000000
 </TASK>
task:kworker/u4:4    state:R  running task     stack:22936 pid:102   ppid:2      flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6873
 irqentry_exit+0x53/0x80 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:653
RIP: 0010:lock_acquire+0x26f/0x5a0 kernel/locking/lockdep.c:5666
Code: 2b 00 74 08 4c 89 f7 e8 3f b5 77 00 f6 44 24 61 02 0f 85 84 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc900015978e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff920002b2f28 RCX: 1ffff920002b2ec8
RDX: dffffc0000000000 RSI: ffffffff8b0c13c0 RDI: ffffffff8b5d5ba0
RBP: ffffc90001597a28 R08: dffffc0000000000 R09: fffffbfff20e7245
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920002b2f24
R13: dffffc0000000000 R14: ffffc90001597940 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 inet_twsk_purge+0x150/0xa40 net/ipv4/inet_timewait_sock.c:295
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x763/0xb60 net/core/net_namespace.c:604
 process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: rcu_preempt kthread starved for 9356 jiffies! g14293 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:26712 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 schedule+0xbf/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:22 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:130 [inline]
RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
RIP: 0010:acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567
Code: 6c db f6 48 83 e3 08 0f 85 0b 01 00 00 4c 8d 74 24 20 e8 34 2b e2 f6 0f 1f 44 00 00 e8 6a 68 db f6 0f 00 2d b3 4d b8 00 fb f4 <4c> 89 f3 48 c1 eb 03 42 80 3c 3b 00 74 08 4c 89 f7 e8 bb f0 32 f7
RSP: 0018:ffffffff8d007b20 EFLAGS: 000002d3
RAX: ffffffff8aaf3326 RBX: 0000000000000000 RCX: ffffffff8d0bd800
RDX: 0000000000000000 RSI: ffffffff8b0c0240 RDI: ffffffff8b5d5ba0
RBP: ffffffff8d007bb0 R08: ffffffff8aaf3308 R09: fffffbfff1a17b01
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffffffff1a00f64
R13: ffff8881482ca004 R14: ffffffff8d007b40 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe43f66698 CR3: 000000007f683000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 </IRQ>
 <TASK>
 acpi_idle_enter+0x352/0x4f0 drivers/acpi/processor_idle.c:704
 cpuidle_enter_state+0x516/0xf80 drivers/cpuidle/cpuidle.c:239
 cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:356
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:236 [inline]
 do_idle+0x3ce/0x680 kernel/sched/idle.c:303
 cpu_startup_entry+0x3d/0x60 kernel/sched/idle.c:401
 rest_init+0x2da/0x300 init/main.c:733
 arch_call_rest_init+0xa/0xa init/main.c:893
 start_kernel+0x496/0x53f init/main.c:1140
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/31 14:15 linux-6.1.y c1cec4dad96b 6fde257d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_readlink
* Struck through repros no longer work on HEAD.