syzbot


INFO: rcu detected stall in full_proxy_write

Status: auto-obsoleted due to no activity on 2026/04/14 15:16
Subsystems: mm
[Documentation on labels]
First crash: 220d, last: 105d

Sample crash report:
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8595/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=26093, q=1577 ncpus=1)
task:syz.3.603       state:R  running task     stack:26872 pid:8595  tgid:8591  ppid:5830   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190
 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x62/0x330 kernel/locking/lockdep.c:5872
Code: ea 18 12 83 f8 07 0f 87 a2 02 00 00 89 c0 48 0f a3 05 d2 6b ef 0e 0f 82 74 02 00 00 8b 35 4a 9c ef 0e 85 f6 0f 85 8d 00 00 00 <48> 8b 44 24 30 65 48 2b 05 e9 e9 18 12 0f 85 ad 02 00 00 48 83 c4
RSP: 0018:ffffc90004737790 EFLAGS: 00000206
RAX: 0000000000000046 RBX: ffffffff8e3c9520 RCX: 00000000a7be7270
RDX: 0000000000000000 RSI: ffffffff8daa50c6 RDI: ffffffff8bf2b680
RBP: 0000000000000002 R08: 000000000127e9da R09: 00000000a0127e9d
R10: 0000000000000002 R11: ffff88803008e6b0 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:867 [inline]
 page_ref_add_unless.constprop.0+0x36/0x390 include/linux/page_ref.h:235
 folio_ref_add_unless include/linux/page_ref.h:248 [inline]
 folio_try_get include/linux/page_ref.h:264 [inline]
 split_huge_pages_all mm/huge_memory.c:4538 [inline]
 split_huge_pages_write+0x10fd/0x2300 mm/huge_memory.c:4829
 full_proxy_write+0x131/0x1a0 fs/debugfs/file.c:388
 vfs_write+0x2a0/0x11d0 fs/read_write.c:684
 ksys_write+0x12a/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7fc4d8f7c9
RSP: 002b:00007f7fc5bd4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f7fc4fe6090 RCX: 00007f7fc4d8f7c9
RDX: 0000000000000001 RSI: 0000200000000100 RDI: 0000000000000008
RBP: 00007f7fc4e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7fc4fe6128 R14: 00007f7fc4fe6090 R15: 00007ffed6e41328
 </TASK>
net_ratelimit: 15455 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
net_ratelimit: 15879 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:52:ec:e5:1e:39:af, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/14 15:09 upstream c537e12daeec d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in full_proxy_write
2025/12/10 18:00 upstream 0048fbb4011e d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in full_proxy_write
2025/09/20 19:40 upstream cd89d487374c 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in full_proxy_write
* Struck through repros no longer work on HEAD.