[syzbot] [mm?] INFO: rcu detected stall in sys_umount (3)

[syzbot] [mm?] INFO: rcu detected stall in sys_umount (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    feffde684ac2 Merge tag 'for-6.13-rc1-tag' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1420a330580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=50c7a61469ce77e7
dashboard link: https://syzkaller.appspot.com/bug?extid=1ec0f904ba50d06110b1
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13c060f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3bb09093023b/disk-feffde68.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9e37e48dc48a/vmlinux-feffde68.xz
kernel image: https://storage.googleapis.com/syzbot-assets/36b46b3a6421/bzImage-feffde68.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1ec0f904ba50d06110b1@syzkaller.appspotmail.com

bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5930/1:b..l
rcu: 	(detected by 0, t=10503 jiffies, g=6361, q=569 ncpus=2)
task:syz-executor    state:R  running task     stack:20208 pid:5930  tgid:5930  ppid:5919   flags:0x00000002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:7078
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:rcu_preempt_read_enter kernel/rcu/tree_plugin.h:390 [inline]
RIP: 0010:__rcu_read_lock+0x27/0xb0 kernel/rcu/tree_plugin.h:413
Code: 90 90 90 f3 0f 1e fa 55 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 4c 8b 3c 25 00 d6 03 00 49 81 c7 44 04 00 00 4c 89 fb <48> c1 eb 03 42 0f b6 04 33 84 c0 75 35 41 8b 2f ff c5 42 0f b6 04
RSP: 0018:ffffc900035f77e0 EFLAGS: 00000286
RAX: ffffffff81ae868a RBX: ffff888026cd5e44 RCX: ffff888026cd5a00
RDX: 0000000000000000 RSI: ffffffff8c5f63c0 RDI: 00007fc1f8581247
RBP: 0000000000000001 R08: ffffffff810a464d R09: ffffc900035f7990
R10: ffffc900035f78f0 R11: ffffffff818b36f0 R12: ffff888026cd5a00
R13: ffffffff818b36f0 R14: dffffc0000000000 R15: ffff888026cd5e44
 rcu_read_lock include/linux/rcupdate.h:847 [inline]
 is_bpf_text_address+0x1f/0x2a0 kernel/bpf/core.c:768
 kernel_text_address+0xa7/0xe0 kernel/extable.c:125
 __kernel_text_address+0xd/0x40 kernel/extable.c:79
 unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_orc.c:369
 arch_stack_walk+0xfd/0x150 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x118/0x1d0 kernel/stacktrace.c:122
 save_stack+0xfb/0x1f0 mm/page_owner.c:156
 __reset_page_owner+0x76/0x430 mm/page_owner.c:297
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0xdef/0x1130 mm/page_alloc.c:2657
 __slab_free+0x31b/0x3d0 mm/slub.c:4509
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4104 [inline]
 slab_alloc_node mm/slub.c:4153 [inline]
 kmem_cache_alloc_noprof+0x1d9/0x380 mm/slub.c:4160
 getname_flags+0xb7/0x540 fs/namei.c:139
 user_path_at+0x24/0x60 fs/namei.c:3069
 ksys_umount fs/namespace.c:2033 [inline]
 __do_sys_umount fs/namespace.c:2041 [inline]
 __se_sys_umount fs/namespace.c:2039 [inline]
 __x64_sys_umount+0xf1/0x170 fs/namespace.c:2039
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc1f8581247
RSP: 002b:00007fc1f886ecc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc1f8581247
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fc1f886ed80
RBP: 00007fc1f886ed80 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fc1f886fe00
R13: 00007fc1f85f3824 R14: 000000000000f97b R15: 00007fc1f886fe40
 </TASK>
rcu: rcu_preempt kthread starved for 10527 jiffies! g6361 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:26264 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_timeout+0x15a/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2045
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2247
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 24 Comm: ksoftirqd/1 Not tainted 6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:unwind_get_return_address+0x56/0x90 arch/x86/kernel/unwind_orc.c:369
Code: 83 c3 48 49 89 df 49 c1 ef 03 43 80 3c 37 00 74 08 48 89 df e8 7b b2 be 00 48 8b 3b e8 c3 73 1e 00 85 c0 74 14 43 80 3c 37 00 <74> 08 48 89 df e8 60 b2 be 00 48 8b 03 eb 02 31 c0 5b 41 5e 41 5f
RSP: 0018:ffffc900001e6d20 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffffc900001e6d88 RCX: ffffffff91790000
RDX: ffffffff91940701 RSI: ffffc900001e0000 RDI: ffffffff81fe1859
RBP: ffffc900001e6dd0 R08: ffffc900001e7120 R09: 0000000000000000
R10: ffffc900001e6d90 R11: fffff5200003cdb4 R12: ffff88801d2e8000
R13: ffffffff818b36f0 R14: dffffc0000000000 R15: 1ffff9200003cdb1
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc1f886ecdc CR3: 000000007d414000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 arch_stack_walk+0xfd/0x150 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x118/0x1d0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4104 [inline]
 slab_alloc_node mm/slub.c:4153 [inline]
 kmem_cache_alloc_noprof+0x1d9/0x380 mm/slub.c:4160
 __skb_ext_alloc net/core/skbuff.c:6924 [inline]
 skb_ext_add+0x14d/0x910 net/core/skbuff.c:7027
 nf_bridge_alloc include/net/netfilter/br_netfilter.h:12 [inline]
 br_nf_pre_routing_ipv6+0x131/0x770 net/bridge/br_netfilter_ipv6.c:172
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
 br_handle_frame+0x9fd/0x1530 net/bridge/br_input.c:424
 __netif_receive_skb_core+0x14eb/0x4690 net/core/dev.c:5566
 __netif_receive_skb_one_core net/core/dev.c:5670 [inline]
 __netif_receive_skb+0x12f/0x650 net/core/dev.c:5785
 process_backlog+0x662/0x15b0 net/core/dev.c:6117
 __napi_poll+0xcb/0x490 net/core/dev.c:6877
 napi_poll net/core/dev.c:6946 [inline]
 net_rx_action+0x89b/0x1240 net/core/dev.c:7068
 handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:554
 run_ksoftirqd+0xca/0x130 kernel/softirq.c:943
 smpboot_thread_fn+0x544/0xa30 kernel/smpboot.c:164
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
net_ratelimit: 52114 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
net_ratelimit: 58692 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)


---
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If the report is already addressed, let syzbot know by replying with:
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Re: [syzbot] [mm?] INFO: rcu detected stall in sys_umount (3)

[syzbot]

syzbot has bisected this issue to:

commit d15121be7485655129101f3960ae6add40204463
Author: Paolo Abeni <pabeni@redhat.com>
Date:   Mon May 8 06:17:44 2023 +0000

    Revert "softirq: Let ksoftirqd do its job"

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1066f9f8580000
start commit:   feffde684ac2 Merge tag 'for-6.13-rc1-tag' of git://git.ker..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1266f9f8580000
console output: https://syzkaller.appspot.com/x/log.txt?x=1466f9f8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=50c7a61469ce77e7
dashboard link: https://syzkaller.appspot.com/bug?extid=1ec0f904ba50d06110b1
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13c060f8580000

Reported-by: syzbot+1ec0f904ba50d06110b1@syzkaller.appspotmail.com
Fixes: d15121be7485 ("Revert "softirq: Let ksoftirqd do its job"")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [syzbot] [mm?] INFO: rcu detected stall in sys_umount (3)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    8f5ae30d69d7 Linux 6.17-rc1
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1321eba2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8c5ac3d8b8abfcb
dashboard link: https://syzkaller.appspot.com/bug?extid=1ec0f904ba50d06110b1
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10cba442580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10a1eba2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/18a2e4bd0c4a/disk-8f5ae30d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3b5395881b25/vmlinux-8f5ae30d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e875f4e3b7ff/Image-8f5ae30d.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/43186d9e448c/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=174ba442580000)

The issue was bisected to:

commit d15121be7485655129101f3960ae6add40204463
Author: Paolo Abeni <pabeni@redhat.com>
Date:   Mon May 8 06:17:44 2023 +0000

    Revert "softirq: Let ksoftirqd do its job"

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1066f9f8580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1266f9f8580000
console output: https://syzkaller.appspot.com/x/log.txt?x=1466f9f8580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1ec0f904ba50d06110b1@syzkaller.appspotmail.com
Fixes: d15121be7485 ("Revert "softirq: Let ksoftirqd do its job"")

watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [syz-executor:6662]
Modules linked in:
irq event stamp: 355416
hardirqs last  enabled at (355415): [<ffff80008b00487c>] __exit_to_kernel_mode arch/arm64/kernel/entry-common.c:86 [inline]
hardirqs last  enabled at (355415): [<ffff80008b00487c>] exit_to_kernel_mode+0xc0/0xf0 arch/arm64/kernel/entry-common.c:96
hardirqs last disabled at (355416): [<ffff80008b001cbc>] __el1_irq arch/arm64/kernel/entry-common.c:650 [inline]
hardirqs last disabled at (355416): [<ffff80008b001cbc>] el1_interrupt+0x24/0x54 arch/arm64/kernel/entry-common.c:668
softirqs last  enabled at (355404): [<ffff8000803d88a0>] softirq_handle_end kernel/softirq.c:425 [inline]
softirqs last  enabled at (355404): [<ffff8000803d88a0>] handle_softirqs+0xaf8/0xc88 kernel/softirq.c:607
softirqs last disabled at (355387): [<ffff800080022028>] __do_softirq+0x14/0x20 kernel/softirq.c:613
CPU: 1 UID: 0 PID: 6662 Comm: syz-executor Not tainted 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : propagation_source fs/pnode.c:77 [inline]
pc : change_mnt_propagation+0xec/0x77c fs/pnode.c:114
lr : propagation_source fs/pnode.c:78 [inline]
lr : change_mnt_propagation+0x120/0x77c fs/pnode.c:114
sp : ffff8000a4a07a90
x29: ffff8000a4a07ac0 x28: dfff800000000000 x27: ffff0000efa88b60
x26: ffff0000efa88bb0 x25: 1fffe0001df51176 x24: ffff0000efa88b18
x23: ffff0000f331b238 x22: ffff0000efa88a80 x21: ffff0000efa88a80
x20: 0000000000040000 x19: ffff0000f3339500 x18: 1fffe000337a0688
x17: ffff80008f7be000 x16: ffff80008af6de48 x15: 0000000000000002
x14: 1fffe0001df5116f x13: 0000000000000000 x12: 0000000000000000
x11: ffff60001df51171 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : ffff0000f33395b8 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000008 x3 : 0000000000000000
x2 : 0000000000000008 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
 next_peer fs/pnode.c:19 [inline] (P)
 propagation_source fs/pnode.c:77 [inline] (P)
 change_mnt_propagation+0xec/0x77c fs/pnode.c:114 (P)
 umount_tree+0x7e4/0xbbc fs/namespace.c:1872
 do_umount fs/namespace.c:-1 [inline]
 path_umount+0x90c/0x980 fs/namespace.c:2095
 ksys_umount fs/namespace.c:2118 [inline]
 __do_sys_umount fs/namespace.c:2123 [inline]
 __se_sys_umount fs/namespace.c:2121 [inline]
 __arm64_sys_umount+0x128/0x174 fs/namespace.c:2121
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6746 Comm: syz-executor Not tainted 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : cpu_relax arch/arm64/include/asm/vdso/processor.h:12 [inline]
pc : path_init+0xdc0/0xe98 fs/namei.c:2537
lr : path_init+0xdc0/0xe98 fs/namei.c:2537
sp : ffff8000a4247680
x29: ffff8000a42476e0 x28: dfff800000000000 x27: 1fffe00019832884
x26: ffff0000cc194420 x25: 0000000000000101 x24: 1ffff00014848f43
x23: ffff80008f745840 x22: ffff8000a4247a1c x21: 0000000000000100
x20: ffff8000a42479e0 x19: 000000000004a017 x18: 0000000000000000
x17: 0000000000000000 x16: ffff80008b007230 x15: 0000000000000001
x14: 1ffff00011ee8b08 x13: 0000000000000000 x12: 0000000000000000
x11: ffff700011ee8b09 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : ffff0000da1e0000 x7 : ffff800080daa4c4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800080da8a84
x2 : 0000000000000000 x1 : 0000000000000004 x0 : 0000000000000001
Call trace:
 path_init+0xdc0/0xe98 fs/namei.c:2537 (P)
 path_openat+0x13c/0x2c40 fs/namei.c:4041
 do_filp_open+0x18c/0x36c fs/namei.c:4073
 do_open_execat+0x124/0x4d8 fs/exec.c:783
 alloc_bprm+0x3c/0x548 fs/exec.c:1410
 do_execveat_common+0x168/0x834 fs/exec.c:1811
 do_execve fs/exec.c:1934 [inline]
 __do_sys_execve fs/exec.c:2010 [inline]
 __se_sys_execve fs/exec.c:2005 [inline]
 __arm64_sys_execve+0x9c/0xb4 fs/exec.c:2005
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596


---
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#syz test: git://repo/address.git branch-or-commit-hash
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Re: [syzbot] [mm?] INFO: rcu detected stall in sys_umount (3)

[Al Viro]

On Mon, Aug 18, 2025 at 02:42:28AM -0700, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    8f5ae30d69d7 Linux 6.17-rc1
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=1321eba2580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8c5ac3d8b8abfcb
> dashboard link: https://syzkaller.appspot.com/bug?extid=1ec0f904ba50d06110b1
> compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
> userspace arch: arm64
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10cba442580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10a1eba2580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/18a2e4bd0c4a/disk-8f5ae30d.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/3b5395881b25/vmlinux-8f5ae30d.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/e875f4e3b7ff/Image-8f5ae30d.gz.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/43186d9e448c/mount_0.gz
>   fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=174ba442580000)
> 
> The issue was bisected to:
> 
> commit d15121be7485655129101f3960ae6add40204463
> Author: Paolo Abeni <pabeni@redhat.com>
> Date:   Mon May 8 06:17:44 2023 +0000
> 
>     Revert "softirq: Let ksoftirqd do its job"

Would be interesting to see how it behaves on 

git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git #fixes (cda250b0fc83)