Message-ID: <68b3b47c.a00a0220.1337b0.002b.GAE@google.com>
Date: Sat, 30 Aug 2025 19:33:32 -0700
From: syzbot <syzbot+455cf6d72dfed822de56@...kaller.appspotmail.com>
To: akpm@...ux-foundation.org, cgroups@...r.kernel.org, hannes@...xchg.org, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, mhocko@...nel.org, 
	muchun.song@...ux.dev, roman.gushchin@...ux.dev, shakeel.butt@...ux.dev, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [mm?] INFO: rcu detected stall in sys_madvise (2)

Hello,

syzbot found the following issue on:

HEAD commit:    dfc0f6373094 Merge tag 'erofs-for-6.17-rc2-fixes' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15580da2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fc3f2c190ebad30b
dashboard link: https://syzkaller.appspot.com/bug?extid=455cf6d72dfed822de56
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4dfa56dd97cf/disk-dfc0f637.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e381d6bdc1d0/vmlinux-dfc0f637.xz
kernel image: https://storage.googleapis.com/syzbot-assets/182bfdad6b5a/bzImage-dfc0f637.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+455cf6d72dfed822de56@...kaller.appspotmail.com

bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P16208/2:b..l P16191/3:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=85289, q=304 ncpus=1)
task:syz.0.1939      state:R  running task     stack:24088 pid:16191 tgid:16191 ppid:5863   task_flags:0x400640 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:7145
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 filemap_map_pages+0xe15/0x1670 mm/filemap.c:3791
 do_fault_around mm/memory.c:5531 [inline]
 do_read_fault mm/memory.c:5564 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xe36/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 __get_user_pages_locked mm/gup.c:1712 [inline]
 get_dump_page+0x257/0x3d0 mm/gup.c:2212
 dump_user_range+0x195/0xb70 fs/coredump.c:1364
 elf_core_dump+0x2929/0x3b60 fs/binfmt_elf.c:2085
 coredump_write fs/coredump.c:1049 [inline]
 vfs_coredump+0x2ba2/0x56d0 fs/coredump.c:1168
 get_signal+0x22e3/0x26d0 kernel/signal.c:3019
 arch_do_signal_or_restart+0x8f/0x790 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 irqentry_exit_to_user_mode+0x12a/0x270 kernel/entry/common.c:73
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x401000
RSP: 002b:000000000000000a EFLAGS: 00010282
RAX: 0000000000000003 RBX: 00007f0e941b5fa0 RCX: 00007f0e93f8ebe9
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000020003b46
RBP: 00007f0e94011e19 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0e941b6038 R14: 00007f0e941b5fa0 R15: 00007ffe733e96c8
 </TASK>
task:syz.0.1943      state:R  running task     stack:24568 pid:16208 tgid:16207 ppid:5863   task_flags:0x400940 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288
 irqentry_exit+0x36/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__ref_is_percpu include/linux/percpu-refcount.h:174 [inline]
RIP: 0010:percpu_ref_tryget_many include/linux/percpu-refcount.h:243 [inline]
RIP: 0010:percpu_ref_tryget include/linux/percpu-refcount.h:266 [inline]
RIP: 0010:obj_cgroup_tryget include/linux/memcontrol.h:767 [inline]
RIP: 0010:__get_obj_cgroup_from_memcg+0x90/0x230 mm/memcontrol.c:2618
Code: 50 b9 02 00 00 00 31 f6 48 c7 c7 60 10 5c 8e e8 76 bc 6e ff e8 41 8b 67 09 5a 85 c0 75 7c 48 89 e8 48 c1 e8 03 42 80 3c 20 00 <0f> 85 67 01 00 00 48 8b 45 00 a8 03 0f 85 eb 00 00 00 65 48 ff 00
RSP: 0018:ffffc9000b176d18 EFLAGS: 00000246
RAX: 1ffff110050ec640 RBX: ffff88805a7b0000 RCX: 00000000ac0bef84
RDX: 0000000000000000 RSI: ffffffff8c162900 RDI: ffffffff8df57e68
RBP: ffff888028763200 R08: 852cca471aa95b22 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000000 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000001 R15: 0000000000000000
 get_obj_cgroup_from_folio+0x148/0x270 mm/memcontrol.c:2738
 swap_zeromap_folio_set mm/page_io.c:206 [inline]
 swap_writeout+0x4bc/0xfe0 mm/page_io.c:264
 writeout mm/vmscan.c:669 [inline]
 pageout mm/vmscan.c:728 [inline]
 shrink_folio_list+0x3e46/0x4880 mm/vmscan.c:1452
 reclaim_folio_list+0xda/0x5d0 mm/vmscan.c:2232
 reclaim_pages+0x47b/0x650 mm/vmscan.c:2269
 madvise_cold_or_pageout_pte_range+0x1546/0x2120 mm/madvise.c:565
 walk_pmd_range mm/pagewalk.c:130 [inline]
 walk_pud_range mm/pagewalk.c:224 [inline]
 walk_p4d_range mm/pagewalk.c:262 [inline]
 walk_pgd_range+0xc02/0x1f50 mm/pagewalk.c:303
 __walk_page_range+0x163/0x820 mm/pagewalk.c:410
 walk_page_range_vma+0x2c7/0xa20 mm/pagewalk.c:705
 madvise_pageout_page_range mm/madvise.c:624 [inline]
 madvise_pageout+0x257/0x540 mm/madvise.c:649
 madvise_vma_behavior+0xb22/0x2d60 mm/madvise.c:1352
 madvise_walk_vmas+0x31f/0x9c0 mm/madvise.c:1669
 madvise_do_behavior+0x1e2/0x530 mm/madvise.c:1885
 do_madvise+0x176/0x240 mm/madvise.c:1978
 __do_sys_madvise mm/madvise.c:1987 [inline]
 __se_sys_madvise mm/madvise.c:1985 [inline]
 __x64_sys_madvise+0xa9/0x110 mm/madvise.c:1985
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0e93f8ebe9
RSP: 002b:00007f0e94d81038 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f0e941b5fa0 RCX: 00007f0e93f8ebe9
RDX: 0000000000000015 RSI: ffffffffffff0001 RDI: 0000000000000000
RBP: 00007f0e94011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0e941b6038 R14: 00007f0e941b5fa0 R15: 00007ffe733e96c8
 </TASK>
rcu: rcu_preempt kthread starved for 374 jiffies! g85289 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:28760 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 11087 Comm: kworker/u8:31 Tainted: GF R                 6.17.0-rc1-syzkaller-00036-gdfc0f6373094 #0 PREEMPT(full) 
Tainted: [F]=FORCED_MODULE, [R]=FORCED_RMMOD
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: bat_events batadv_tt_purge
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:26 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:127 [inline]
RIP: 0010:lock_is_held_type+0x54/0x150 kernel/locking/lockdep.c:5936
Code: b1 45 08 85 c0 0f 85 ce 00 00 00 65 4c 8b 25 0b 70 45 08 41 8b 94 24 ec 0a 00 00 85 d2 0f 85 b6 00 00 00 48 89 fd 41 89 f6 9c <8f> 04 24 fa 48 c7 c7 da ef f3 8d 4d 8d ac 24 f0 0a 00 00 45 31 ff
RSP: 0018:ffffc90000a08360 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffffffff903855c8
RBP: ffffffff903855c8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888026a30000
R13: 00000000ffffffff R14: 00000000ffffffff R15: ffff88807b867000
FS:  0000000000000000(0000) GS:ffff8881247c6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb361800218 CR3: 000000000e380000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 lock_is_held include/linux/lockdep.h:249 [inline]
 lockdep_rtnl_is_held+0x1b/0x40 net/core/rtnetlink.c:182
 __in6_dev_get include/net/addrconf.h:347 [inline]
 ip6_ignore_linkdown include/net/addrconf.h:443 [inline]
 find_match+0x34b/0x15d0 net/ipv6/route.c:780
 __find_rr_leaf+0x140/0xe00 net/ipv6/route.c:868
 find_rr_leaf net/ipv6/route.c:889 [inline]
 rt6_select net/ipv6/route.c:933 [inline]
 fib6_table_lookup+0x57c/0xa30 net/ipv6/route.c:2233
 ip6_pol_route+0x1cc/0x1230 net/ipv6/route.c:2269
 pol_lookup_func include/net/ip6_fib.h:617 [inline]
 fib6_rule_lookup+0x536/0x720 net/ipv6/fib6_rules.c:120
 ip6_route_input_lookup net/ipv6/route.c:2338 [inline]
 ip6_route_input+0x662/0xc00 net/ipv6/route.c:2641
 ip6_rcv_finish_core.constprop.0+0x1a0/0x5d0 net/ipv6/ip6_input.c:66
 ip6_rcv_finish net/ipv6/ip6_input.c:77 [inline]
 NF_HOOK include/linux/netfilter.h:318 [inline]
 NF_HOOK include/linux/netfilter.h:312 [inline]
 ipv6_rcv+0x1e8/0x650 net/ipv6/ip6_input.c:311
 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5979
 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6092
 process_backlog+0x442/0x15e0 net/core/dev.c:6444
 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7489
 napi_poll net/core/dev.c:7552 [inline]
 net_rx_action+0xa9f/0xfe0 net/core/dev.c:7679
 handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
 do_softirq kernel/softirq.c:480 [inline]
 do_softirq+0xb2/0xf0 kernel/softirq.c:467
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x100/0x120 kernel/softirq.c:407
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 batadv_tt_local_purge+0x21c/0x3c0 net/batman-adv/translation-table.c:1315
 batadv_tt_purge+0x8b/0xb80 net/batman-adv/translation-table.c:3509
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
net_ratelimit: 11652 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 16288 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)


---
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 syzkaller@...glegroups.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

Powered by blists - more mailing lists