[v6.1] INFO: rcu detected stall in generic_file_write_iter (3)
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syzbot
Jul 11, 2026, 2:33:33 PM (yesterday) Jul 11
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 090666d3cc90 Linux 6.1.177
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=128670b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f5aae664b2df43c2
dashboard link: https://syzkaller.appspot.com/bug?extid=376d38b3fd0cd006839b
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0a97b9de9f21/disk-090666d3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/40f470f8fbd0/vmlinux-090666d3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/baabfa2bfd44/bzImage-090666d3.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+376d38...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (0 ticks this GP) idle=496c/1/0x4000000000000002 softirq=60590/60590 fqs=2099
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P15204
(detected by 1, t=10502 jiffies, g=100217, q=2195 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 15204 Comm: syz.4.2887 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x2a/0x80 kernel/kcov.c:320
Code: 48 8b 04 24 65 48 8b 0d b4 49 80 7e 65 8b 15 b5 49 80 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 1c 16 00 00 00 <74> 4e 8b 91 f8 15 00 00 83 fa 03 75 43 48 8b 91 00 16 00 00 44 8b
RSP: 0018:ffffc90000007618 EFLAGS: 00000046
RAX: ffffffff81a4ac87 RBX: 0000000000000000 RCX: ffff88802b885a00
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000007710 R08: ffffc90000007797 R09: ffffc90000007760
R10: dffffc0000000000 R11: fffff52000000ef3 R12: dffffc0000000000
R13: ffff888028afe000 R14: 0000000000000100 R15: dffffc0000000000
FS: 00007f4eea14e6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000d000 CR3: 0000000020318000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
perf_prepare_sample+0x1527/0x2020 kernel/events/core.c:7678
__perf_event_output kernel/events/core.c:7730 [inline]
perf_event_output_forward+0x197/0x2f0 kernel/events/core.c:7750
__perf_event_overflow+0x457/0x630 kernel/events/core.c:9496
perf_swevent_overflow kernel/events/core.c:9579 [inline]
perf_swevent_event+0x315/0x570 kernel/events/core.c:9630
perf_tp_event+0x36b/0xc10 kernel/events/core.c:10064
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10032
perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:variable_ffs arch/x86/include/asm/bitops.h:319 [inline]
RIP: 0010:handle_softirqs+0x1b7/0x910 kernel/softirq.c:584
Code: 89 7c 24 2c 0f b7 db 48 c7 c7 80 0d 8b 8a e8 e0 1f e1 08 65 66 c7 05 66 62 b4 7e 00 00 e8 91 46 39 00 fb 49 c7 c5 c0 a0 80 8c <89> 5c 24 34 b8 ff ff ff ff 0f bc 44 24 34 41 89 c6 41 ff c6 0f 84
RSP: 0018:ffffc90000007e20 EFLAGS: 00000282
RAX: e413f881327ae500 RBX: 0000000000000200 RCX: e413f881327ae500
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: ffffffff8adf42e0
RBP: ffffc90000007f30 R08: ffffffff90b10277 R09: 1ffffffff216204e
R10: dffffc0000000000 R11: fffffbfff216204f R12: dffffc0000000000
R13: ffffffff8c80a0c0 R14: ffff88802b885a00 R15: 000000000000000a
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:rcu_read_unlock_special+0x1/0x510 kernel/rcu/tree_plugin.h:630
Code: 5b 66 00 eb b0 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 94 49 89 fd 4c 89 f7 e8 0c 5b 66 00 4c 89 ef eb 84 0f 1f 80 00 00 00 00 55 <48> 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec c0 00 00
RSP: 0018:ffffc90003c376e0 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff88802b885e3c RCX: 0000000000080000
RDX: ffffc9000e33b000 RSI: 0000000000014c7a RDI: ffff88802b885a00
RBP: ffffc90003c37830 R08: ffff88802b885a00 R09: 0000000000000002
R10: 0000000000000406 R11: 0000000000000002 R12: 1ffff11005710bc7
R13: ffff888026b0660c R14: ffff88802b885e40 R15: dffffc0000000000
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
mt_find+0x605/0x830 lib/maple_tree.c:6558
find_vma+0x12c/0x1b0 mm/mmap.c:1898
lock_mm_and_find_vma+0x71/0x2f0 mm/memory.c:5385
do_user_addr_fault+0x2e8/0xb20 arch/x86/mm/fault.c:1310
handle_page_fault arch/x86/mm/fault.c:1429 [inline]
exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:fault_in_readable+0x13e/0x1f0 mm/gup.c:1915
Code: 78 5a c4 ff 4d 89 f4 49 81 cc ff 0f 00 00 4d 89 f7 49 01 dc 49 81 e4 00 f0 ff ff 4d 39 e6 77 44 e8 57 5a c4 ff 4d 39 e7 74 47 <41> 8a 07 88 44 24 07 49 81 c7 00 10 00 00 4d 39 e7 74 07 e8 3a 5a
RSP: 0018:ffffc90003c37ab0 EFLAGS: 00050287
RAX: ffffffff81bdc749 RBX: 0000000000001000 RCX: 0000000000080000
RDX: ffffc9000e33b000 RSI: 0000000000014725 RDI: 0000000000014726
RBP: 0000000000000000 R08: ffff88802b885a00 R09: 0000000000000002
R10: 0000000000000006 R11: 0000000000000002 R12: 000020000000e000
R13: dffffc0000000000 R14: 000020000000c300 R15: 000020000000d000
fault_in_iov_iter_readable+0xbf/0x2f0 lib/iov_iter.c:356
generic_perform_write+0x1f1/0x5c0 mm/filemap.c:3852
__generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960
generic_file_write_iter+0xab/0x2e0 mm/filemap.c:3989
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x482/0x9a0 fs/read_write.c:584
ksys_write+0x14d/0x260 fs/read_write.c:637
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: 0033:0x7f4ee919de59
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:00007f4eea14e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f4ee9425fa0 RCX: 00007f4ee919de59
RDX: 000000000000fe33 RSI: 0000200000000300 RDI: 0000000000000009
RBP: 00007f4ee9233e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ee9426038 R14: 00007f4ee9425fa0 R15: 00007ffe55c4b218
</TASK>
task:syz.4.2887 state:R running task stack:24624 pid:15204 ppid:4284 flags:0x0000400c
Call Trace:
<TASK>
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 090666d3cc90 Linux 6.1.177
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=128670b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f5aae664b2df43c2
dashboard link: https://syzkaller.appspot.com/bug?extid=376d38b3fd0cd006839b
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0a97b9de9f21/disk-090666d3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/40f470f8fbd0/vmlinux-090666d3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/baabfa2bfd44/bzImage-090666d3.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+376d38...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (0 ticks this GP) idle=496c/1/0x4000000000000002 softirq=60590/60590 fqs=2099
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P15204
(detected by 1, t=10502 jiffies, g=100217, q=2195 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 15204 Comm: syz.4.2887 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x2a/0x80 kernel/kcov.c:320
Code: 48 8b 04 24 65 48 8b 0d b4 49 80 7e 65 8b 15 b5 49 80 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 1c 16 00 00 00 <74> 4e 8b 91 f8 15 00 00 83 fa 03 75 43 48 8b 91 00 16 00 00 44 8b
RSP: 0018:ffffc90000007618 EFLAGS: 00000046
RAX: ffffffff81a4ac87 RBX: 0000000000000000 RCX: ffff88802b885a00
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000007710 R08: ffffc90000007797 R09: ffffc90000007760
R10: dffffc0000000000 R11: fffff52000000ef3 R12: dffffc0000000000
R13: ffff888028afe000 R14: 0000000000000100 R15: dffffc0000000000
FS: 00007f4eea14e6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000d000 CR3: 0000000020318000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
perf_prepare_sample+0x1527/0x2020 kernel/events/core.c:7678
__perf_event_output kernel/events/core.c:7730 [inline]
perf_event_output_forward+0x197/0x2f0 kernel/events/core.c:7750
__perf_event_overflow+0x457/0x630 kernel/events/core.c:9496
perf_swevent_overflow kernel/events/core.c:9579 [inline]
perf_swevent_event+0x315/0x570 kernel/events/core.c:9630
perf_tp_event+0x36b/0xc10 kernel/events/core.c:10064
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10032
perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:variable_ffs arch/x86/include/asm/bitops.h:319 [inline]
RIP: 0010:handle_softirqs+0x1b7/0x910 kernel/softirq.c:584
Code: 89 7c 24 2c 0f b7 db 48 c7 c7 80 0d 8b 8a e8 e0 1f e1 08 65 66 c7 05 66 62 b4 7e 00 00 e8 91 46 39 00 fb 49 c7 c5 c0 a0 80 8c <89> 5c 24 34 b8 ff ff ff ff 0f bc 44 24 34 41 89 c6 41 ff c6 0f 84
RSP: 0018:ffffc90000007e20 EFLAGS: 00000282
RAX: e413f881327ae500 RBX: 0000000000000200 RCX: e413f881327ae500
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: ffffffff8adf42e0
RBP: ffffc90000007f30 R08: ffffffff90b10277 R09: 1ffffffff216204e
R10: dffffc0000000000 R11: fffffbfff216204f R12: dffffc0000000000
R13: ffffffff8c80a0c0 R14: ffff88802b885a00 R15: 000000000000000a
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:rcu_read_unlock_special+0x1/0x510 kernel/rcu/tree_plugin.h:630
Code: 5b 66 00 eb b0 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 94 49 89 fd 4c 89 f7 e8 0c 5b 66 00 4c 89 ef eb 84 0f 1f 80 00 00 00 00 55 <48> 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec c0 00 00
RSP: 0018:ffffc90003c376e0 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff88802b885e3c RCX: 0000000000080000
RDX: ffffc9000e33b000 RSI: 0000000000014c7a RDI: ffff88802b885a00
RBP: ffffc90003c37830 R08: ffff88802b885a00 R09: 0000000000000002
R10: 0000000000000406 R11: 0000000000000002 R12: 1ffff11005710bc7
R13: ffff888026b0660c R14: ffff88802b885e40 R15: dffffc0000000000
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
mt_find+0x605/0x830 lib/maple_tree.c:6558
find_vma+0x12c/0x1b0 mm/mmap.c:1898
lock_mm_and_find_vma+0x71/0x2f0 mm/memory.c:5385
do_user_addr_fault+0x2e8/0xb20 arch/x86/mm/fault.c:1310
handle_page_fault arch/x86/mm/fault.c:1429 [inline]
exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:fault_in_readable+0x13e/0x1f0 mm/gup.c:1915
Code: 78 5a c4 ff 4d 89 f4 49 81 cc ff 0f 00 00 4d 89 f7 49 01 dc 49 81 e4 00 f0 ff ff 4d 39 e6 77 44 e8 57 5a c4 ff 4d 39 e7 74 47 <41> 8a 07 88 44 24 07 49 81 c7 00 10 00 00 4d 39 e7 74 07 e8 3a 5a
RSP: 0018:ffffc90003c37ab0 EFLAGS: 00050287
RAX: ffffffff81bdc749 RBX: 0000000000001000 RCX: 0000000000080000
RDX: ffffc9000e33b000 RSI: 0000000000014725 RDI: 0000000000014726
RBP: 0000000000000000 R08: ffff88802b885a00 R09: 0000000000000002
R10: 0000000000000006 R11: 0000000000000002 R12: 000020000000e000
R13: dffffc0000000000 R14: 000020000000c300 R15: 000020000000d000
fault_in_iov_iter_readable+0xbf/0x2f0 lib/iov_iter.c:356
generic_perform_write+0x1f1/0x5c0 mm/filemap.c:3852
__generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960
generic_file_write_iter+0xab/0x2e0 mm/filemap.c:3989
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x482/0x9a0 fs/read_write.c:584
ksys_write+0x14d/0x260 fs/read_write.c:637
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: 0033:0x7f4ee919de59
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:00007f4eea14e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f4ee9425fa0 RCX: 00007f4ee919de59
RDX: 000000000000fe33 RSI: 0000200000000300 RDI: 0000000000000009
RBP: 00007f4ee9233e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ee9426038 R14: 00007f4ee9425fa0 R15: 00007ffe55c4b218
</TASK>
task:syz.4.2887 state:R running task stack:24624 pid:15204 ppid:4284 flags:0x0000400c
Call Trace:
<TASK>
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
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