====================================================== WARNING: possible circular locking dependency detected 4.20.0+ #1 Not tainted ------------------------------------------------------ syz-executor1/21585 is trying to acquire lock: 0000000040b62404 (&p->pi_lock){-.-.}, at: try_to_wake_up+0xb9/0x1480 kernel/sched/core.c:1965 but task is already holding lock: 00000000150fbfae (&pgdat->kswapd_wait){....}, at: __wake_up_common_lock+0x19b/0x390 kernel/sched/wait.c:120 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&pgdat->kswapd_wait){....}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 __wake_up_common_lock+0x19b/0x390 kernel/sched/wait.c:120 __wake_up+0xe/0x10 kernel/sched/wait.c:145 wakeup_kswapd+0x5ba/0x8f0 mm/vmscan.c:3982 steal_suitable_fallback+0x50d/0x7c0 mm/page_alloc.c:2217 __rmqueue_fallback mm/page_alloc.c:2502 [inline] __rmqueue mm/page_alloc.c:2528 [inline] rmqueue_bulk mm/page_alloc.c:2550 [inline] __rmqueue_pcplist mm/page_alloc.c:3021 [inline] rmqueue_pcplist mm/page_alloc.c:3050 [inline] rmqueue mm/page_alloc.c:3072 [inline] get_page_from_freelist+0x2f53/0x5190 mm/page_alloc.c:3491 __alloc_pages_nodemask+0x4fd/0xdc0 mm/page_alloc.c:4529 alloc_pages_current+0x107/0x210 mm/mempolicy.c:2106 alloc_pages include/linux/gfp.h:509 [inline] __get_free_pages+0xc/0x40 mm/page_alloc.c:4573 tlb_next_batch mm/mmu_gather.c:29 [inline] __tlb_remove_page_size+0x2ee/0x510 mm/mmu_gather.c:133 __tlb_remove_page include/asm-generic/tlb.h:187 [inline] zap_pte_range mm/memory.c:1093 [inline] zap_pmd_range mm/memory.c:1192 [inline] zap_pud_range mm/memory.c:1221 [inline] zap_p4d_range mm/memory.c:1242 [inline] unmap_page_range+0xf45/0x25a0 mm/memory.c:1263 unmap_single_vma+0x19d/0x300 mm/memory.c:1308 unmap_vmas+0x17c/0x310 mm/memory.c:1339 exit_mmap+0x2d4/0x5d0 mm/mmap.c:3140 __mmput kernel/fork.c:1051 [inline] mmput+0x240/0x640 kernel/fork.c:1072 exit_mm kernel/exit.c:545 [inline] do_exit+0x9d3/0x2650 kernel/exit.c:854 do_group_exit+0x177/0x430 kernel/exit.c:970 get_signal+0x8b4/0x19b0 kernel/signal.c:2517 do_signal+0x91/0x1e80 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2f7/0x3b0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&(&zone->lock)->rlock){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 rmqueue mm/page_alloc.c:3082 [inline] get_page_from_freelist+0x13d0/0x5190 mm/page_alloc.c:3491 __alloc_pages_nodemask+0x4fd/0xdc0 mm/page_alloc.c:4529 alloc_pages_current+0x107/0x210 mm/mempolicy.c:2106 alloc_pages include/linux/gfp.h:509 [inline] depot_save_stack+0x3da/0x460 lib/stackdepot.c:260 save_stack+0xa9/0xd0 mm/kasan/common.c:79 set_track mm/kasan/common.c:85 [inline] kasan_kmalloc mm/kasan/common.c:482 [inline] kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:397 kmem_cache_alloc+0x12d/0x710 mm/slab.c:3541 kmem_cache_zalloc include/linux/slab.h:730 [inline] fill_pool lib/debugobjects.c:134 [inline] __debug_object_init+0xb1d/0x12d0 lib/debugobjects.c:379 debug_object_init lib/debugobjects.c:431 [inline] debug_object_activate+0x348/0x550 lib/debugobjects.c:512 debug_timer_activate kernel/time/timer.c:708 [inline] debug_activate kernel/time/timer.c:763 [inline] __mod_timer kernel/time/timer.c:1040 [inline] mod_timer kernel/time/timer.c:1101 [inline] add_timer+0x4e6/0x1470 kernel/time/timer.c:1137 __queue_delayed_work+0x253/0x390 kernel/workqueue.c:1533 queue_delayed_work_on+0x19a/0x200 kernel/workqueue.c:1558 queue_delayed_work include/linux/workqueue.h:527 [inline] schedule_delayed_work include/linux/workqueue.h:628 [inline] unaccount_event kernel/events/core.c:4311 [inline] _free_event+0x1116/0x15d0 kernel/events/core.c:4419 put_event+0x47/0x60 kernel/events/core.c:4532 perf_event_release_kernel+0x890/0xf70 kernel/events/core.c:4638 perf_release+0x37/0x50 kernel/events/core.c:4648 __fput+0x3c5/0xb10 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x1f4/0x2b0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x32a/0x3b0 arch/x86/entry/common.c:166 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&base->lock){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 lock_timer_base+0xb7/0x2a0 kernel/time/timer.c:937 __mod_timer kernel/time/timer.c:1009 [inline] mod_timer kernel/time/timer.c:1101 [inline] add_timer+0x884/0x1470 kernel/time/timer.c:1137 __queue_delayed_work+0x253/0x390 kernel/workqueue.c:1533 queue_delayed_work_on+0x19a/0x200 kernel/workqueue.c:1558 queue_delayed_work include/linux/workqueue.h:527 [inline] schedule_delayed_work include/linux/workqueue.h:628 [inline] psi_group_change kernel/sched/psi.c:485 [inline] psi_task_change+0x3ea/0x590 kernel/sched/psi.c:534 psi_enqueue kernel/sched/stats.h:82 [inline] enqueue_task kernel/sched/core.c:727 [inline] activate_task+0x1f8/0x470 kernel/sched/core.c:751 wake_up_new_task+0x50c/0xd30 kernel/sched/core.c:2423 _do_fork+0x2a5/0x1170 kernel/fork.c:2247 kernel_thread+0x34/0x40 kernel/fork.c:2281 rest_init+0x28/0x37b init/main.c:409 arch_call_rest_init+0xe/0x1b start_kernel+0x882/0x8bd init/main.c:741 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&rq->lock){-.-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 rq_lock kernel/sched/sched.h:1149 [inline] task_fork_fair+0xb5/0x7a0 kernel/sched/fair.c:10083 sched_fork+0x437/0xb90 kernel/sched/core.c:2359 copy_process+0x1ff6/0x8730 kernel/fork.c:1893 _do_fork+0x1a9/0x1170 kernel/fork.c:2222 kernel_thread+0x34/0x40 kernel/fork.c:2281 rest_init+0x28/0x37b init/main.c:409 arch_call_rest_init+0xe/0x1b start_kernel+0x882/0x8bd init/main.c:741 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #0 (&p->pi_lock){-.-.}: lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3841 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 try_to_wake_up+0xb9/0x1480 kernel/sched/core.c:1965 default_wake_function+0x30/0x50 kernel/sched/core.c:3710 autoremove_wake_function+0x79/0x360 kernel/sched/wait.c:375 __wake_up_common+0x1d3/0x7d0 kernel/sched/wait.c:92 __wake_up_common_lock+0x1c6/0x390 kernel/sched/wait.c:121 __wake_up+0xe/0x10 kernel/sched/wait.c:145 wakeup_kswapd+0x5ba/0x8f0 mm/vmscan.c:3982 steal_suitable_fallback+0x50d/0x7c0 mm/page_alloc.c:2217 __rmqueue_fallback mm/page_alloc.c:2502 [inline] __rmqueue mm/page_alloc.c:2528 [inline] rmqueue_bulk mm/page_alloc.c:2550 [inline] __rmqueue_pcplist mm/page_alloc.c:3021 [inline] rmqueue_pcplist mm/page_alloc.c:3050 [inline] rmqueue mm/page_alloc.c:3072 [inline] get_page_from_freelist+0x2f53/0x5190 mm/page_alloc.c:3491 __alloc_pages_nodemask+0x4fd/0xdc0 mm/page_alloc.c:4529 alloc_pages_current+0x107/0x210 mm/mempolicy.c:2106 alloc_pages include/linux/gfp.h:509 [inline] __get_free_pages+0xc/0x40 mm/page_alloc.c:4573 tlb_next_batch mm/mmu_gather.c:29 [inline] __tlb_remove_page_size+0x2ee/0x510 mm/mmu_gather.c:133 __tlb_remove_page include/asm-generic/tlb.h:187 [inline] zap_pte_range mm/memory.c:1093 [inline] zap_pmd_range mm/memory.c:1192 [inline] zap_pud_range mm/memory.c:1221 [inline] zap_p4d_range mm/memory.c:1242 [inline] unmap_page_range+0xf45/0x25a0 mm/memory.c:1263 unmap_single_vma+0x19d/0x300 mm/memory.c:1308 unmap_vmas+0x17c/0x310 mm/memory.c:1339 exit_mmap+0x2d4/0x5d0 mm/mmap.c:3140 __mmput kernel/fork.c:1051 [inline] mmput+0x240/0x640 kernel/fork.c:1072 exit_mm kernel/exit.c:545 [inline] do_exit+0x9d3/0x2650 kernel/exit.c:854 do_group_exit+0x177/0x430 kernel/exit.c:970 get_signal+0x8b4/0x19b0 kernel/signal.c:2517 do_signal+0x91/0x1e80 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2f7/0x3b0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &p->pi_lock --> &(&zone->lock)->rlock --> &pgdat->kswapd_wait Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pgdat->kswapd_wait); lock(&(&zone->lock)->rlock); lock(&pgdat->kswapd_wait); lock(&p->pi_lock); *** DEADLOCK *** 3 locks held by syz-executor1/21585: #0: 000000002e48af14 (&(ptlock_ptr(page))->rlock#2){+.+.}, at: spin_lock include/linux/spinlock.h:329 [inline] #0: 000000002e48af14 (&(ptlock_ptr(page))->rlock#2){+.+.}, at: zap_pte_range mm/memory.c:1051 [inline] #0: 000000002e48af14 (&(ptlock_ptr(page))->rlock#2){+.+.}, at: zap_pmd_range mm/memory.c:1192 [inline] #0: 000000002e48af14 (&(ptlock_ptr(page))->rlock#2){+.+.}, at: zap_pud_range mm/memory.c:1221 [inline] #0: 000000002e48af14 (&(ptlock_ptr(page))->rlock#2){+.+.}, at: zap_p4d_range mm/memory.c:1242 [inline] #0: 000000002e48af14 (&(ptlock_ptr(page))->rlock#2){+.+.}, at: unmap_page_range+0x95d/0x25a0 mm/memory.c:1263 #1: 000000003a0b2bcc (&(&zone->lock)->rlock){-.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] #1: 000000003a0b2bcc (&(&zone->lock)->rlock){-.-.}, at: rmqueue_bulk mm/page_alloc.c:2548 [inline] #1: 000000003a0b2bcc (&(&zone->lock)->rlock){-.-.}, at: __rmqueue_pcplist mm/page_alloc.c:3021 [inline] #1: 000000003a0b2bcc (&(&zone->lock)->rlock){-.-.}, at: rmqueue_pcplist mm/page_alloc.c:3050 [inline] #1: 000000003a0b2bcc (&(&zone->lock)->rlock){-.-.}, at: rmqueue mm/page_alloc.c:3072 [inline] #1: 000000003a0b2bcc (&(&zone->lock)->rlock){-.-.}, at: get_page_from_freelist+0x1ab1/0x5190 mm/page_alloc.c:3491 #2: 00000000150fbfae (&pgdat->kswapd_wait){....}, at: __wake_up_common_lock+0x19b/0x390 kernel/sched/wait.c:120 stack backtrace: CPU: 0 PID: 21585 Comm: syz-executor1 Not tainted 4.20.0+ #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1db/0x2d0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1224 check_prev_add kernel/locking/lockdep.c:1866 [inline] check_prevs_add kernel/locking/lockdep.c:1979 [inline] validate_chain kernel/locking/lockdep.c:2350 [inline] __lock_acquire+0x3014/0x4a30 kernel/locking/lockdep.c:3338 lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3841 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 try_to_wake_up+0xb9/0x1480 kernel/sched/core.c:1965 default_wake_function+0x30/0x50 kernel/sched/core.c:3710 autoremove_wake_function+0x79/0x360 kernel/sched/wait.c:375 __wake_up_common+0x1d3/0x7d0 kernel/sched/wait.c:92 __wake_up_common_lock+0x1c6/0x390 kernel/sched/wait.c:121 __wake_up+0xe/0x10 kernel/sched/wait.c:145 wakeup_kswapd+0x5ba/0x8f0 mm/vmscan.c:3982 steal_suitable_fallback+0x50d/0x7c0 mm/page_alloc.c:2217 __rmqueue_fallback mm/page_alloc.c:2502 [inline] __rmqueue mm/page_alloc.c:2528 [inline] rmqueue_bulk mm/page_alloc.c:2550 [inline] __rmqueue_pcplist mm/page_alloc.c:3021 [inline] rmqueue_pcplist mm/page_alloc.c:3050 [inline] rmqueue mm/page_alloc.c:3072 [inline] get_page_from_freelist+0x2f53/0x5190 mm/page_alloc.c:3491 __alloc_pages_nodemask+0x4fd/0xdc0 mm/page_alloc.c:4529 alloc_pages_current+0x107/0x210 mm/mempolicy.c:2106 alloc_pages include/linux/gfp.h:509 [inline] __get_free_pages+0xc/0x40 mm/page_alloc.c:4573 tlb_next_batch mm/mmu_gather.c:29 [inline] __tlb_remove_page_size+0x2ee/0x510 mm/mmu_gather.c:133 __tlb_remove_page include/asm-generic/tlb.h:187 [inline] zap_pte_range mm/memory.c:1093 [inline] zap_pmd_range mm/memory.c:1192 [inline] zap_pud_range mm/memory.c:1221 [inline] zap_p4d_range mm/memory.c:1242 [inline] unmap_page_range+0xf45/0x25a0 mm/memory.c:1263 unmap_single_vma+0x19d/0x300 mm/memory.c:1308 unmap_vmas+0x17c/0x310 mm/memory.c:1339 exit_mmap+0x2d4/0x5d0 mm/mmap.c:3140 __mmput kernel/fork.c:1051 [inline] mmput+0x240/0x640 kernel/fork.c:1072 exit_mm kernel/exit.c:545 [inline] do_exit+0x9d3/0x2650 kernel/exit.c:854 do_group_exit+0x177/0x430 kernel/exit.c:970 get_signal+0x8b4/0x19b0 kernel/signal.c:2517 do_signal+0x91/0x1e80 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2f7/0x3b0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457ec9 Code: Bad RIP value. RSP: 002b:00007f18b3a4acf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000073bf08 RCX: 0000000000457ec9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000073bf08 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000073bf0c R13: 00007ffef1134b2f R14: 00007f18b3a4b9c0 R15: 000000000073bf0c ------------[ cut here ]------------ downgrading a read lock WARNING: CPU: 1 PID: 20860 at kernel/locking/lockdep.c:3553 __lock_downgrade kernel/locking/lockdep.c:3553 [inline] WARNING: CPU: 1 PID: 20860 at kernel/locking/lockdep.c:3553 lock_downgrade+0x4d2/0x910 kernel/locking/lockdep.c:3816