syzbot
INFO: rcu detected stall in drm_gem_mmap (2)
Status: auto-obsoleted due to no activity on 2026/08/05 08:33
Subsystems:
kernel
Labels:
prio:high
[Documentation on labels]
First crash: 108d, last: 108d
Sample crash report:
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P17489/1:b..l
rcu: (detected by 1, t=10502 jiffies, g=141233, q=3771 ncpus=2)
task:syz.5.3540 state:R running task stack:24888 pid:17489 tgid:17478 ppid:10692 task_flags:0x400040 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x17b4/0x5680 kernel/sched/core.c:7189
preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
irqentry_exit+0x14f/0x730 kernel/entry/common.c:164
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 51 94 06 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 3b 4f 97 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 48 4e 92
RSP: 0018:ffffc900051ae9b8 EFLAGS: 00000286
RAX: e17df4b6db6b4500 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 00000000b025bb95 RSI: ffffffff8e218a98 RDI: ffffffff8c28ace0
RBP: ffffffff8176f256 R08: ffffffff8176f256 R09: ffffffff8e95cd60
R10: ffffc900051aeb28 R11: fffff52000a35d71 R12: 0000000000000002
R13: ffffffff8e95cd60 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:838 [inline]
class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
unwind_next_frame+0xc3/0x2550 arch/x86/kernel/unwind_orc.c:495
__unwind_start+0x5b8/0x760 arch/x86/kernel/unwind_orc.c:787
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xe3/0x150 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2689 [inline]
slab_free mm/slub.c:6250 [inline]
kmem_cache_free+0x182/0x650 mm/slub.c:6377
__merge_or_add_vmap_area mm/vmalloc.c:1473 [inline]
merge_or_add_vmap_area mm/vmalloc.c:1523 [inline]
decay_va_pool_node+0x786/0xec0 mm/vmalloc.c:2250
__purge_vmap_area_lazy+0x160/0xb40 mm/vmalloc.c:2355
_vm_unmap_aliases+0x73d/0x7e0 mm/vmalloc.c:2990
change_page_attr_set_clr+0x307/0xf40 arch/x86/mm/pat/set_memory.c:2101
_set_pages_array+0x193/0x270 arch/x86/mm/pat/set_memory.c:2530
drm_gem_shmem_get_pages_locked+0x2fa/0x480 drivers/gpu/drm/drm_gem_shmem_helper.c:236
drm_gem_shmem_mmap+0x193/0x440 drivers/gpu/drm/drm_gem_shmem_helper.c:740
drm_gem_mmap_obj+0x18a/0x4c0 drivers/gpu/drm/drm_gem.c:1227
drm_gem_mmap+0xc5/0x1a0 drivers/gpu/drm/drm_gem.c:1370
vfs_mmap include/linux/fs.h:2071 [inline]
mmap_file mm/internal.h:168 [inline]
__mmap_new_file_vma mm/vma.c:2496 [inline]
__mmap_new_vma mm/vma.c:2562 [inline]
__mmap_region mm/vma.c:2771 [inline]
mmap_region+0x19a3/0x22a0 mm/vma.c:2857
do_mmap+0xc39/0x10c0 mm/mmap.c:560
vm_mmap_pgoff+0x2c9/0x4f0 mm/util.c:581
ksys_mmap_pgoff+0x51e/0x760 mm/mmap.c:606
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f156fb9cdd9
RSP: 002b:00007f156ddb4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f156fe16180 RCX: 00007f156fb9cdd9
RDX: 0000000000000004 RSI: 0000000000004000 RDI: 0000200000001000
RBP: 00007f156fc32d69 R08: 0000000000000009 R09: 0000000100000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f156fe16218 R14: 00007f156fe16180 R15: 00007f156ff3fa48
</TASK>
rcu: rcu_preempt kthread starved for 4573 jiffies! g141233 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:27640 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x17b4/0x5680 kernel/sched/core.c:7189
__schedule_loop kernel/sched/core.c:7268 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7283
schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: 0b 7e 02 e9 93 f6 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 53 21 21 00 fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e20 EFLAGS: 00000246
RAX: 00000000010d1417 RBX: ffffffff819a91ea RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8dfa5b55 RDI: ffffffff8c28ace0
RBP: ffffc90000197f10 R08: ffff8880b87339db R09: 1ffff110170e673b
R10: dffffc0000000000 R11: ffffed10170e673c R12: 0000000000000001
R13: 1ffff11003b5b000 R14: 0000000000000001 R15: 1ffff11003b5b000
FS: 0000000000000000(0000) GS:ffff888125390000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555703414e8 CR3: 000000007a262000 CR4: 00000000003526f0
Call Trace:
<TASK>
arch_safe_halt arch/x86/kernel/process.c:766 [inline]
default_idle+0x9/0x20 arch/x86/kernel/process.c:767
default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:199 [inline]
do_idle+0x36a/0x5f0 kernel/sched/idle.c:352
cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451
start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
common_startup_64+0x13e/0x147
</TASK>
net_ratelimit: 15728 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:96:ef:ac:45:ec:fc, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:96:ef:ac:45:ec:fc, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 20496 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:96:ef:ac:45:ec:fc, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:96:ef:ac:45:ec:fc, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
Struck through repros no longer work on HEAD.