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rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5778/1:b..l P16703/1:b..l P16706/1:b..l rcu: (detected by 1, t=10502 jiffies, g=101445, q=287 ncpus=2) task:syz-executor state:R running task stack:24712 pid:16706 ppid:5765 flags:0x00004000 Call Trace: <TASK> context_switch kernel/sched/core.c:5381 [inline] __schedule+0x15ae/0x4660 kernel/sched/core.c:6700 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010 irqentry_exit+0x67/0x70 kernel/entry/common.c:438 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758 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:ffffc9000442f080 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: e432416fc2f90800 RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1c7be0 RBP: ffffc9000442f190 R08: dffffc0000000000 R09: 1ffffffff22378a0 R10: dffffc0000000000 R11: fffffbfff22378a1 R12: 1ffff92000885e1c R13: ffffffff8d131da0 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire include/linux/rcupdate.h:334 [inline] rcu_read_lock include/linux/rcupdate.h:786 [inline] ext4_get_group_desc+0x12f/0x4d0 fs/ext4/balloc.c:286 ext4_mb_prefetch_fini+0xa8/0x1d0 fs/ext4/mballoc.c:2814 ext4_mb_regular_allocator+0x29b/0x36c0 fs/ext4/mballoc.c:3021 ext4_mb_new_blocks+0xc9c/0x42f0 fs/ext4/mballoc.c:6254 ext4_ext_map_blocks+0x1826/0x6890 fs/ext4/extents.c:4415 ext4_map_blocks+0x9db/0x1a90 fs/ext4/inode.c:654 ext4_getblk+0x1c9/0x720 fs/ext4/inode.c:864 ext4_bread+0x2a/0x170 fs/ext4/inode.c:920 ext4_append+0x2bf/0x560 fs/ext4/namei.c:83 ext4_init_new_dir+0x2bc/0x550 fs/ext4/namei.c:3030 ext4_mkdir+0x4c7/0xc90 fs/ext4/namei.c:3076 vfs_mkdir+0x2a5/0x470 fs/namei.c:4121 do_mkdirat+0x1dc/0x450 fs/namei.c:4144 __do_sys_mkdir fs/namei.c:4164 [inline] __se_sys_mkdir fs/namei.c:4162 [inline] __x64_sys_mkdir+0x6e/0x80 fs/namei.c:4162 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: 0033:0x7fc163dcb227 RSP: 002b:00007ffdccdb54d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000053 RAX: ffffffffffffffda RBX: 00007ffdccdb5602 RCX: 00007fc163dcb227 RDX: 00000000072aadd0 RSI: 00000000000001c0 RDI: 00007ffdccdb55f0 RBP: 8421084210842109 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000072aadd0 R13: 00007ffdccdb5602 R14: 0000000000000004 R15: 00007fc163e5a040 </TASK> task:syz.0.2438 state:R running task stack:26056 pid:16703 ppid:16109 flags:0x00004000 Call Trace: <TASK> context_switch kernel/sched/core.c:5381 [inline] __schedule+0x15ae/0x4660 kernel/sched/core.c:6700 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891 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:1357 exit_mm+0x23f/0x340 kernel/exit.c:570 do_exit+0x909/0x2530 kernel/exit.c:871 do_group_exit+0x22d/0x2f0 kernel/exit.c:1026 __do_sys_exit_group kernel/exit.c:1037 [inline] __se_sys_exit_group kernel/exit.c:1035 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1035 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: 0033:0x7efc3af9de59 RSP: 002b:00007ffd08d446a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007efc3af9de59 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffd08d4470c R08: 0000000000000000 R09: 00000000000927c0 R10: 00007efc3b226038 R11: 0000000000000246 R12: 000000000000000e R13: 00000000000927c0 R14: 000000000013d36a R15: 00007ffd08d44760 </TASK> task:syz-executor state:R running task stack:20560 pid:5778 ppid:1 flags:0x00004006 Call Trace: <TASK> context_switch kernel/sched/core.c:5381 [inline] __schedule+0x15ae/0x4660 kernel/sched/core.c:6700 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010 irqentry_exit+0x67/0x70 kernel/entry/common.c:438 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758 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:ffffc900043af6a0 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: bc224cce933bac00 RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1c7be0 RBP: ffffc900043af7c0 R08: dffffc0000000000 R09: 1ffffffff22378a0 R10: dffffc0000000000 R11: fffffbfff22378a1 R12: 1ffff92000875ee0 R13: ffffffff8d131da0 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire include/linux/rcupdate.h:334 [inline] rcu_read_lock include/linux/rcupdate.h:786 [inline] page_ext_get+0x3e/0x2b0 mm/page_ext.c:508 __reset_page_owner+0x2e/0x190 mm/page_owner.c:145 reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1182 [inline] free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459 vfree+0x1a7/0x340 mm/vmalloc.c:2868 kcov_put kernel/kcov.c:438 [inline] kcov_close+0x2b/0x50 kernel/kcov.c:534 __fput+0x221/0x930 fs/file_table.c:384 task_work_run+0x1d4/0x260 kernel/task_work.c:245 exit_task_work include/linux/task_work.h:43 [inline] do_exit+0x986/0x2530 kernel/exit.c:884 do_group_exit+0x22d/0x2f0 kernel/exit.c:1026 get_signal+0x12a6/0x1390 kernel/signal.c:2903 arch_do_signal_or_restart+0xc2/0x7b0 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fa6f315e68e RSP: 002b:00007fff29338888 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: fffffffffffffe00 RBX: 000055555bbdd500 RCX: 00007fa6f315e68e RDX: 0000000000000030 RSI: 00007fff29338980 RDI: 00000000000000f9 RBP: 00007fff2933892c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000258 R13: 000000000000004d R14: 000000000013cbc6 R15: 00007fff29338980 </TASK> rcu: rcu_preempt kthread starved for 10603 jiffies! g101445 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:27152 pid:17 ppid:2 flags:0x00004000 Call Trace: <TASK> context_switch kernel/sched/core.c:5381 [inline] __schedule+0x15ae/0x4660 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 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: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148 Code: dc 23 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 43 67 44 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2c 89 cb 80 f9 RSP: 0018:ffffc90000187de0 EFLAGS: 000002c6 RAX: b177a4b0e7ab6000 RBX: ffffffff81628b01 RCX: b177a4b0e7ab6000 RDX: 0000000000000001 RSI: ffffffff8acacb60 RDI: ffffffff8b1c7be0 RBP: ffffc90000187f20 R08: ffff8880b8f36bab R09: 1ffff110171e6d75 R10: dffffc0000000000 R11: ffffed10171e6d76 R12: 1ffff92000030fc8 R13: dffffc0000000000 R14: 1ffff110036cd780 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b34722ff8 CR3: 0000000026dc5000 CR4: 00000000003506e0 Call Trace: <TASK> arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:178 [inline] do_idle+0x221/0x5c0 kernel/sched/idle.c:302 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:401 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323 secondary_startup_64_no_verify+0x179/0x17b </TASK>
| Time | Kernel | Commit | Syzkaller | Config | Log | Report | Syz repro | C repro | VM info | Assets (help?) | Manager | Title |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026/07/02 03:33 | linux-6.6.y | d1cfde2d5d15 | 27192279 | .config | console log | report | info | [disk image] [vmlinux] [kernel image] | ci2-linux-6-6-kasan | INFO: rcu detected stall in sys_mkdir |