INFO: rcu detected stall in mmap_pgoff

Status: upstream: reported on 2026/09/09 00:30
Reported-by: syzbot+b19416715e13f5a1b74f@syzkaller.appspotmail.com
First crash: 16d, last: 7h51m
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in mmap_pgoff (6) fs 1 6 736d 831d 0/29 auto-obsoleted due to no activity on 2024/12/18 09:17
upstream INFO: rcu detected stall in mmap_pgoff (5) mm fs 1 2 1156d 1185d 0/29 auto-obsoleted due to no activity on 2023/10/25 16:56
linux-4.19 INFO: rcu detected stall in mmap_pgoff 1 syz error 2 1983d 2051d 0/1 upstream: reported syz repro on 2021/02/11 18:33
linux-5.15 INFO: rcu detected stall in mmap_pgoff 1 1 1081d 1081d 0/3 auto-obsoleted due to no activity on 2024/01/17 20:08
linux-5.15 INFO: rcu detected stall in mmap_pgoff (2) 1 10 507d 813d 0/3 auto-obsoleted due to no activity on 2025/08/14 00:27
linux-5.15 INFO: rcu detected stall in mmap_pgoff (4) 1 1 43d 43d 0/3 upstream: reported on 2026/08/13 09:40
upstream INFO: rcu detected stall in mmap_pgoff (4) mm 1 1 1283d 1283d 0/29 auto-obsoleted due to no activity on 2023/05/21 07:37
upstream INFO: rcu detected stall in mmap_pgoff crypto 1 3 1776d 1784d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in mmap_pgoff (3) mm 1 1 1473d 1473d 0/29 auto-obsoleted due to no activity on 2022/12/11 19:43
linux-5.15 INFO: rcu detected stall in mmap_pgoff (3) 1 9 180d 367d 0/3 auto-obsoleted due to no activity on 2026/07/07 03:07
upstream INFO: rcu detected stall in mmap_pgoff (2) kernel 1 1 1672d 1672d 0/29 auto-closed as invalid on 2022/05/26 19:52

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P16535/1:b..l P16540/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=106361, q=231 ncpus=1)
task:rm              state:R  running task     stack:24360 pid:16540 ppid:16501  flags:0x00004000
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:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5760
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc90005337700 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 098c8292caa41700
RDX: 0000000000000000 RSI: ffffffff8acade60 RDI: ffffffff8b1d3ba0
RBP: ffffc90005337808 R08: dffffc0000000000 R09: 1ffffffff223d6a0
R10: dffffc0000000000 R11: fffffbfff223d6a1 R12: 1ffff92000a66eec
R13: ffffffff8d1320e0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 ima_match_policy+0x121/0x1fa0 security/integrity/ima/ima_policy.c:752
 ima_get_action+0x75/0xb0 security/integrity/ima/ima_api.c:199
 process_measurement+0x2df/0x1d50 security/integrity/ima/ima_main.c:239
 ima_file_mmap+0x184/0x1d0 security/integrity/ima/ima_main.c:460
 vm_mmap_pgoff+0x128/0x3f0 mm/util.c:552
 ksys_mmap_pgoff+0x4c9/0x720 mm/mmap.c:1431
 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: 0033:0x7f7b4c341242
RSP: 002b:00007ffd303ed0d8 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f7b4c055000 RCX: 00007f7b4c341242
RDX: 0000000000000005 RSI: 0000000000008000 RDI: 00007f7b4c055000
RBP: 0000000000000812 R08: 0000000000000003 R09: 0000000000003000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffd303ed128
R13: 00007f7b4c31e580 R14: 00007ffd303ed550 R15: 00000fffa607da1e
 </TASK>
task:syz.1.2520      state:R  running task     stack:25384 pid:16535 ppid:12218  flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6868
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6892
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1523 [inline]
 zap_pmd_range mm/memory.c:1571 [inline]
 zap_pud_range mm/memory.c:1600 [inline]
 zap_p4d_range mm/memory.c:1621 [inline]
 unmap_page_range+0x2577/0x32f0 mm/memory.c:1642
 unmap_vmas+0x286/0x3f0 mm/memory.c:1732
 exit_mmap+0x238/0xb90 mm/mmap.c:3302
 __mmput+0x118/0x3a0 kernel/fork.c:1362
 exit_mm+0x23f/0x340 kernel/exit.c:576
 do_exit+0x909/0x2530 kernel/exit.c:877
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1032
 __do_sys_exit_group kernel/exit.c:1043 [inline]
 __se_sys_exit_group kernel/exit.c:1041 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1041
 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: 0033:0x7fcb3899e159
RSP: 002b:00007ffe5b8e1ec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcb3899e159
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffe5b8e1f2c R08: 0000000000000000 R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 00000000000000e4
R13: 00000000000927c0 R14: 000000000010fe64 R15: 00007ffe5b8e1f80
 </TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g106361 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:27848 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 16541 Comm: syz.6.2522 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:debug_lockdep_rcu_enabled+0xd/0x30 kernel/rcu/update.c:319
Code: 48 c7 c6 a0 ef ca 8a e8 81 fe bf f6 0f 0b eb d1 cc cc cc cc cc cc cc cc cc cc cc cc cc f3 0f 1e fa 31 c0 83 3d bf e1 fa 03 00 <74> 1d 83 3d 36 15 fb 03 00 74 14 65 48 8b 0d 00 67 72 75 31 c0 83
RSP: 0018:ffffc9000515f3f8 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff8880219a6800 RCX: 0000000000000005
RDX: ffffc9000d2ba000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc9000515f528 R08: ffff888074c38000 R09: 0000000000000003
R10: 0000000000000002 R11: 0000000000000002 R12: 0000000000000005
R13: dffffc0000000000 R14: ffffffff8d12a380 R15: ffff888023cc2400
FS:  00007f3999e206c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ec12ff8 CR3: 000000002f8ab000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 mt_slot lib/maple_tree.c:814 [inline]
 mtree_lookup_walk lib/maple_tree.c:3755 [inline]
 mtree_load+0x4a1/0x840 lib/maple_tree.c:6264
 irq_to_desc kernel/irq/irqdesc.c:384 [inline]
 kstat_irqs kernel/irq/irqdesc.c:970 [inline]
 kstat_irqs_usr+0xd2/0x3f0 kernel/irq/irqdesc.c:1001
 show_all_irqs fs/proc/stat.c:76 [inline]
 show_stat+0x1094/0x1390 fs/proc/stat.c:171
 seq_read_iter+0x464/0xc50 fs/seq_file.c:230
 call_read_iter include/linux/fs.h:2012 [inline]
 copy_splice_read+0x3f2/0x8b0 fs/splice.c:364
 splice_direct_to_actor+0x261/0x8e0 fs/splice.c:1069
 do_splice_direct+0x1d5/0x2f0 fs/splice.c:1194
 do_sendfile+0x52b/0xe80 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64+0x145/0x1a0 fs/read_write.c:1308
 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: 0033:0x7f3998f9e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3999e20028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f3999226090 RCX: 00007f3998f9e159
RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000006
RBP: 00007f399903506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000020000023896 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3999226128 R14: 00007f3999226090 R15: 00007fff75b3a3e8
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/25 09:00 linux-6.6.y 79643295eba1 f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in mmap_pgoff
2026/09/09 00:29 linux-6.6.y 8b73de7da85f 243b72f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in mmap_pgoff
* Struck through repros no longer work on HEAD.