INFO: rcu detected stall in mmap_file (4)

Status: upstream: reported on 2026/06/14 00:35
Reported-by: syzbot+bde8280833fcc88121dd@syzkaller.appspotmail.com
First crash: 65d, last: 2d05h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in mmap_file (3) 1 3 168d 339d 0/3 auto-obsoleted due to no activity on 2026/06/11 12:22
linux-5.15 INFO: rcu detected stall in mmap_file 1 1 604d 604d 0/3 auto-obsoleted due to no activity on 2025/04/01 14:21
linux-6.1 INFO: rcu detected stall in mmap_file 1 1 83d 83d 0/3 upstream: reported on 2026/05/27 21:33
linux-5.15 INFO: rcu detected stall in mmap_file (2) 1 1 449d 449d 0/3 auto-obsoleted due to no activity on 2025/09/02 23:08

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 GPs behind) idle=b3f/1/0x4000000000000002 softirq=47327/47328 fqs=5249 
	(detected by 1, t=10502 jiffies, g=65941, q=464)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 16235 Comm: syz.4.2460 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:memset+0x22/0x40 mm/kasan/shadow.c:47
Code: 00 00 00 e9 30 ef ff ff 55 41 56 53 48 89 d3 89 f5 49 89 fe 48 8b 4c 24 18 48 89 d6 ba 01 00 00 00 e8 12 ef ff ff 84 c0 74 11 <4c> 89 f7 89 ee 48 89 da 5b 41 5e 5d e9 0d ad 50 02 31 c0 5b 41 5e
RSP: 0018:ffffc900000070e8 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000010 RCX: ffffffff81351823
RDX: 0000000000000001 RSI: 0000000000000010 RDI: ffffc90000007250
RBP: 0000000000000000 R08: ffffc9000000725f R09: 1ffff92000000e4b
R10: dffffc0000000000 R11: fffff52000000e4c R12: 1ffffffff1c6804f
R13: 1ffffffff1c6804f R14: ffffc90000007250 R15: ffffffff8e34027e
FS:  000055556d42a500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000011 CR3: 0000000056c81000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 unwind_next_frame+0x9e3/0x1cf0 arch/x86/kernel/unwind_orc.c:547
 perf_callchain_kernel+0x470/0x760 arch/x86/events/core.c:2783
 get_perf_callchain+0x356/0x460 kernel/events/callchain.c:200
 perf_callchain kernel/events/core.c:7606 [inline]
 perf_prepare_sample+0x352/0x1cb0 kernel/events/core.c:7633
 __perf_event_output kernel/events/core.c:7802 [inline]
 perf_event_output_forward+0x185/0x2e0 kernel/events/core.c:7822
 __perf_event_overflow+0x35f/0x550 kernel/events/core.c:9515
 perf_tp_event+0x324/0xbe0 kernel/events/core.c:10047
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 02 20 9d 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007ae0 EFLAGS: 00000206
RAX: 3e7b19b15cee5000 RBX: 1ffff92000000f60 RCX: 3e7b19b15cee5000
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4200
RBP: ffffc90000007bc0 R08: ffffffff901ee0f7 R09: 1ffffffff203dc1e
R10: dffffc0000000000 R11: fffffbfff203dc1f R12: ffffffff8c323400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 ieee80211_rx_napi+0x216/0x390 net/mac80211/rx.c:5019
 ieee80211_rx include/net/mac80211.h:4573 [inline]
 ieee80211_handle_queued_frames+0x104/0x1a0 net/mac80211/main.c:237
 tasklet_action_common+0x2ad/0x410 kernel/softirq.c:806
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 1f c1 88 f7 65 8b 05 90 e8 38 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000438f980 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 3e7b19b15cee5000
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001
RBP: ffffc9000438fa18 R08: ffffffff901ee0f7 R09: 1ffffffff203dc1e
R10: dffffc0000000000 R11: fffffbfff203dc1f R12: dffffc0000000000
R13: ffffc90010e91000 R14: ffffffff965556d0 R15: 1ffff92000871f30
 __debug_check_no_obj_freed lib/debugobjects.c:999 [inline]
 debug_check_no_obj_freed+0x471/0x520 lib/debugobjects.c:1020
 __vunmap+0x278/0xa80 mm/vmalloc.c:2614
 kcov_mmap+0x89/0x120 kernel/kcov.c:498
 call_mmap include/linux/fs.h:2178 [inline]
 mmap_file+0x5d/0xb0 mm/util.c:1092
 __mmap_region mm/mmap.c:1796 [inline]
 mmap_region+0x1048/0x1730 mm/mmap.c:2933
 do_mmap+0x801/0xe30 mm/mmap.c:1586
 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:551
 ksys_mmap_pgoff+0x4e2/0x790 mm/mmap.c:1635
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4cfc6b8e42
Code: 4f 01 00 0f 1f 44 00 00 41 f7 c1 ff 0f 00 00 75 27 55 89 cd 53 48 89 fb 48 85 ff 74 3b 41 89 ea 48 89 df b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 6e 5b 5d c3 0f 1f 00 48 c7 c0 e8 ff ff ff 64
RSP: 002b:00007ffef4d41a98 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f4cfa4ae000 RCX: 00007f4cfc6b8e42
RDX: 0000000000000003 RSI: 0000000000400000 RDI: 00007f4cfa4ae000
RBP: 0000000000000011 R08: 00000000000000db R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000206 R12: 0000000000000003
R13: 0000000000000003 R14: 0000000000000000 R15: 00007f4cfc940fa0
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/16 17:07 linux-5.15.y aabd761612db 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mmap_file
2026/06/19 06:42 linux-5.15.y dc027a595035 a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in mmap_file
2026/06/14 00:35 linux-5.15.y dc027a595035 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mmap_file
* Struck through repros no longer work on HEAD.