INFO: rcu detected stall in vma_expand (4)

Status: upstream: reported on 2026/07/29 12:00
Reported-by: syzbot+24ae7c2559dfdd55e23c@syzkaller.appspotmail.com
First crash: 14d, last: 14d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in vma_expand origin:lts-only 1 syz error 1 94d 94d 0/2 upstream: reported syz repro on 2026/05/10 14:35
linux-6.1 INFO: rcu detected stall in vma_expand 1 1 980d 980d 0/3 auto-obsoleted due to no activity on 2024/03/15 20:47
upstream INFO: rcu detected stall in vma_expand mm 1 8 713d 829d 0/29 auto-obsoleted due to no activity on 2024/11/27 12:01
linux-6.1 INFO: rcu detected stall in vma_expand (3) 1 4 198d 378d 0/3 auto-obsoleted due to no activity on 2026/05/06 20:38
linux-6.1 INFO: rcu detected stall in vma_expand (2) 1 1 742d 742d 0/3 auto-obsoleted due to no activity on 2024/11/09 10:52

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5097/1:b..l P6628/1:b..l
	(detected by 0, t=10502 jiffies, g=27853, q=121 ncpus=2)
task:dhcpcd-run-hook state:R  running task     stack:23376 pid:6628  ppid:3933   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6875
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x0/0x80 kernel/kcov.c:321
Code: 28 4d 39 ca 77 22 89 ff 89 f6 49 ff c0 4c 89 01 48 c7 44 11 08 05 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 c3 90 <48> 8b 04 24 65 48 8b 0d 64 37 80 7e 65 8b 15 65 37 80 7e 81 e2 00
RSP: 0018:ffffc90003737658 EFLAGS: 00000246
RAX: 1ffff1100f8d810f RBX: dffffc0000000000 RCX: ffff88807c6c0808
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000000
RBP: ffffc90003737810 R08: ffff888076248000 R09: 0000000000000003
R10: 0000000000000003 R11: 0000000000000000 R12: 000000000000000e
R13: ffffffffffffffff R14: ffff88807c6c0800 R15: 0000000000000001
 mas_data_end lib/maple_tree.c:1493 [inline]
 mt_validate_nulls lib/maple_tree.c:7200 [inline]
 mt_validate+0x454b/0x4c60 lib/maple_tree.c:7249
 validate_mm_mt+0xd9/0x420 mm/mmap.c:295
 validate_mm+0xe1/0x2e0 mm/mmap.c:332
 vma_expand+0x7d4/0x850 mm/mmap.c:604
 __mmap_region mm/mmap.c:2740 [inline]
 mmap_region+0xc69/0x1c50 mm/mmap.c:2916
 do_mmap+0x9ce/0x10d0 mm/mmap.c:1436
 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:520
 ksys_mmap_pgoff+0x4bf/0x720 mm/mmap.c:1482
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9f812cd242
RSP: 002b:00007ffc4a0a85d8 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f9f80f7a000 RCX: 00007f9f812cd242
RDX: 0000000000000001 RSI: 0000000000026000 RDI: 00007f9f80f7a000
RBP: 0000000000000812 R08: 0000000000000003 R09: 000000000003a000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffc4a0a8660
R13: 00007f9f80fac6b0 R14: 00007ffc4a0a8a10 R15: 00000fff894150be
 </TASK>
task:udevd           state:R  running task     stack:25904 pid:5097  ppid:3638   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6875
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__kasan_check_read+0x8/0x10 mm/kasan/shadow.c:31
Code: 5d c3 48 c7 c7 6b b0 61 8c eb 0a 48 c7 c7 4a 2d 46 8c 48 89 de e8 b8 83 51 08 31 ed eb d7 00 00 cc cc 89 f6 48 8b 0c 24 31 d2 <e9> c3 ec ff ff 0f 1f 00 89 f6 48 8b 0c 24 ba 01 00 00 00 e9 b0 ec
RSP: 0018:ffffc9000c38f478 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8163f964
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e210ae8
RBP: ffffc9000c38f598 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52001871ed5 R12: 0000000000000000
R13: 1ffff92001871e9c R14: 0000000000000000 R15: dffffc0000000000
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:444 [inline]
 cpu_online include/linux/cpumask.h:1030 [inline]
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0xd4/0x4a0 kernel/locking/lockdep.c:5647
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 is_bpf_text_address+0x43/0x2a0 kernel/bpf/core.c:735
 kernel_text_address+0x9c/0xd0 kernel/extable.c:125
 __kernel_text_address+0x9/0x30 kernel/extable.c:79
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 kmem_cache_free+0xf7/0x2a0 mm/slub.c:3709
 remove_vma mm/mmap.c:144 [inline]
 exit_mmap+0x4a4/0x970 mm/mmap.c:3272
 __mmput+0x118/0x3a0 kernel/fork.c:1206
 exit_mm+0x24d/0x350 kernel/exit.c:566
 do_exit+0x958/0x2570 kernel/exit.c:868
 do_group_exit+0x229/0x2e0 kernel/exit.c:1024
 __do_sys_exit_group kernel/exit.c:1035 [inline]
 __se_sys_exit_group kernel/exit.c:1033 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1033
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6cc3af16c5
RSP: 002b:00007ffe5a868418 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000055f9d6ce82e0 RCX: 00007f6cc3af16c5
RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000
RBP: 000055f9d6cbe910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe5a868460 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10587 jiffies! g27853 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=23443
rcu: rcu_preempt kthread starved for 10593 jiffies! g27853 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:28112 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1350 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:741
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/29 11:59 linux-6.1.y dc5c83b7f5f8 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in vma_expand
* Struck through repros no longer work on HEAD.