syzbot
INFO: rcu detected stall in sys_newfstatat (2)
Status:
upstream: reported on 2026/05/10 20:40
Reported-by: syzbot+e56fb7f0a6923e2175ba@syzkaller.appspotmail.com
First crash: 137d, last: 12h07m
Sample crash report:
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): P5141/1:b..l
rcu: (detected by 1, t=10504 jiffies, g=21501, q=243 ncpus=2)
task:udevd state:R running task stack:23208 pid:5141 ppid:1 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7011
irqentry_exit+0x67/0x70 kernel/entry/common.c:441
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:check_kcov_mode kernel/kcov.c:180 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x30/0x60 kernel/kcov.c:212
Code: 04 24 65 48 8b 0d a0 2c 7c 7e 65 8b 15 a1 2c 7c 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 24 16 00 00 00 74 2c <8b> 91 00 16 00 00 83 fa 02 75 21 48 8b 91 08 16 00 00 48 8b 32 48
RSP: 0018:ffffc900032f75a0 EFLAGS: 00000246
RAX: ffffffff81eb11c1 RBX: 0000000000000008 RCX: ffff88807de19e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffff88801bc52d3f R09: 1ffff1100378a5a7
R10: dffffc0000000000 R11: ffffed100378a5a8 R12: 0000000000000001
R13: 1ffffffff2e6b948 R14: ffff88801bc52d40 R15: 0000000000000003
__page_table_check_zero+0x291/0x4b0 mm/page_table_check.c:160
page_table_check_free include/linux/page_table_check.h:41 [inline]
free_pages_prepare mm/page_alloc.c:1183 [inline]
free_unref_page_prepare+0x7e6/0x8f0 mm/page_alloc.c:2366
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
discard_slab mm/slub.c:2127 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
put_cpu_partial+0x17c/0x250 mm/slub.c:2743
__slab_free+0x319/0x400 mm/slub.c:3700
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
slab_alloc_node mm/slub.c:3495 [inline]
__kmem_cache_alloc_node+0x194/0x250 mm/slub.c:3534
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0xa7/0x240 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
tomoyo_realpath_from_path+0xe6/0x5c0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x282/0x560 security/tomoyo/file.c:822
security_inode_getattr+0xd3/0x120 security/security.c:2190
vfs_getattr fs/stat.c:173 [inline]
vfs_statx+0x172/0x680 fs/stat.c:248
vfs_fstatat+0x12a/0x1b0 fs/stat.c:299
__do_sys_newfstatat fs/stat.c:463 [inline]
__se_sys_newfstatat fs/stat.c:457 [inline]
__x64_sys_newfstatat+0x149/0x1f0 fs/stat.c:457
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb853311b0a
RSP: 002b:00007fff96acf148 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 000055726b2a0400 RCX: 00007fb853311b0a
RDX: 00007fff96acf150 RSI: 000055726b28e296 RDI: 00000000ffffff9c
RBP: 000055728a292148 R08: 000000000da85b6f R09: 0000000000745d1e
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff96acf150 R14: 0000000000000000 R15: 0000000000000000
</TASK>
net_ratelimit: 487 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:ea:e6:88:25:f4:86, 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 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:ea:e6:88:25:f4:86, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
net_ratelimit: 3660 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:ea:e6:88:25:f4:86, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
Struck through repros no longer work on HEAD.