syzbot


INFO: rcu detected stall in sys_readlink (2)

Status: auto-obsoleted due to no activity on 2024/11/07 23:07
Reported-by: syzbot+4266c312676f3f5f97e1@syzkaller.appspotmail.com
First crash: 150d, last: 125d
Similar bugs (8)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_readlink (2) kernel 3 691d 750d 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 460d 460d 0/3 auto-obsoleted due to no activity on 2023/12/08 09:32
upstream INFO: rcu detected stall in sys_readlink fs 1 955d 955d 0/28 auto-closed as invalid on 2022/07/22 05:22
upstream INFO: rcu detected stall in sys_readlink (4) fs 2 365d 368d 0/28 auto-obsoleted due to no activity on 2024/03/02 18:22
linux-6.1 INFO: rcu detected stall in sys_readlink 3 32d 124d 0/3 upstream: reported on 2024/07/31 14:16
upstream INFO: rcu detected stall in sys_readlink (3) bpf fs 2 567d 573d 0/28 auto-obsoleted due to no activity on 2023/08/14 04:05
upstream INFO: rcu detected stall in sys_readlink (5) fs syz 23 17d 45d 0/28 upstream: reported syz repro on 2024/10/18 11:28
android-5-15 BUG: soft lockup in sys_readlink 2 175d 234d 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): P3028/1:b..l
	(detected by 1, t=10502 jiffies, g=8097, q=592)
task:udevd           state:R  running task     stack:24512 pid: 3028 ppid:     1 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6780
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:193
Code: 1f 84 00 00 00 00 00 0f 1f 00 53 48 89 fb e8 17 00 00 00 48 8b 3d 08 ed 68 0c 48 89 de 5b e9 c7 fc 48 00 cc cc cc cc cc cc cc <48> 8b 04 24 65 48 8b 0d 54 0e 82 7e 65 8b 15 55 0e 82 7e f7 c2 00
RSP: 0018:ffffc90002da77b0 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff8880187c91e0 RCX: 0000000080000000
RDX: ffff88807d4ed940 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff81dc301a R09: fffff520000f159d
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff8880187c91e0
R13: ffff88801f0a4758 R14: 00000000ef19cbd6 R15: dffffc0000000000
 hlist_bl_first_rcu include/linux/rculist_bl.h:24 [inline]
 __d_lookup+0x17f/0x730 fs/dcache.c:2430
 lookup_fast+0xdc/0x7b0 fs/namei.c:1621
 walk_component+0x115/0x610 fs/namei.c:1972
 link_path_walk+0x642/0xd90
 path_lookupat+0xa9/0x450 fs/namei.c:2454
 filename_lookup+0x230/0x5c0 fs/namei.c:2484
 user_path_at_empty+0x40/0x180 fs/namei.c:2883
 do_readlinkat+0x114/0x3a0 fs/stat.c:442
 __do_sys_readlink fs/stat.c:475 [inline]
 __se_sys_readlink fs/stat.c:472 [inline]
 __x64_sys_readlink+0x7b/0x90 fs/stat.c:472
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f56688f4d47
RSP: 002b:00007ffd5c6daa78 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffd5c6daa88 RCX: 00007f56688f4d47
RDX: 0000000000000400 RSI: 00007ffd5c6daa88 RDI: 00007ffd5c6daf68
RBP: 0000000000000400 R08: 0000561307f09c24 R09: 0000000000000000
R10: 0000000000000812 R11: 0000000000000246 R12: 00007ffd5c6daf68
R13: 00007ffd5c6daed8 R14: 0000561307ee5910 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10401 jiffies! g8097 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:26144 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:108 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:562
vkms_vblank_simulate: vblank timer overrun

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/30 23:06 linux-5.15.y 7e89efd3ae1c 6fde257d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_readlink
2024/07/25 01:32 linux-5.15.y 7c6d66f0266f d1a1b0ca .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_readlink
2024/07/05 21:29 linux-5.15.y f45bea23c39c 2a40360c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_readlink
* Struck through repros no longer work on HEAD.