rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P11465/1:b..l P3638/1:b..l (detected by 0, t=10502 jiffies, g=96625, q=400 ncpus=2) task:udevd state:R running task stack:23040 pid:3638 ppid:1 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873 irqentry_exit+0x63/0x70 kernel/entry/common.c:439 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0010:hlist_bl_is_locked include/linux/list_bl.h:158 [inline] RIP: 0010:hlist_bl_first_rcu include/linux/rculist_bl.h:24 [inline] RIP: 0010:__d_lookup+0x189/0x7c0 fs/dcache.c:2492 Code: ff 43 80 3c 3e 00 74 08 48 89 df e8 21 d9 eb ff 48 8b 1b 48 89 de 48 83 e6 01 31 ff e8 f0 ad 9b ff 48 83 e3 01 48 8b 6c 24 10 <4c> 8b 74 24 08 75 30 e8 0b de 84 ff 89 c3 31 ff 89 c6 e8 50 ad 9b RSP: 0018:ffffc900032b7808 EFLAGS: 00000246 RAX: ffffffff81e52c50 RBX: 0000000000000000 RCX: ffff88807c8b5940 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff8880256fb8f8 R08: dffffc0000000000 R09: fffff520000c1a36 R10: fffff520000c1a36 R11: 1ffff920000c1a35 R12: ffff8880237bd358 R13: ffffffff81e52b5b R14: 1ffff920000c1a35 R15: dffffc0000000000 lookup_fast+0x7c/0x4d0 fs/namei.c:1656 walk_component fs/namei.c:2002 [inline] link_path_walk+0x5f2/0xe50 fs/namei.c:2333 path_lookupat+0x9d/0x440 fs/namei.c:2486 filename_lookup+0x1f0/0x500 fs/namei.c:2516 vfs_statx+0x109/0x650 fs/stat.c:229 vfs_fstatat fs/stat.c:267 [inline] __do_sys_newfstatat fs/stat.c:437 [inline] __se_sys_newfstatat fs/stat.c:431 [inline] __x64_sys_newfstatat+0x155/0x1e0 fs/stat.c:431 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fd307711b0a RSP: 002b:00007ffd95c2d918 EFLAGS: 00000246 ORIG_RAX: 0000000000000106 RAX: ffffffffffffffda RBX: 00007ffd95c2ddb0 RCX: 00007fd307711b0a RDX: 00007ffd95c2d920 RSI: 00007ffd95c2ddb0 RDI: 00000000ffffff9c RBP: 00005637e99c8910 R08: 0000000000000000 R09: 0000000000000020 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd95c2d9b0 R13: 00005637af358100 R14: 0000000000000000 R15: 00007ffd95c2e4e0 task:udevd state:R running task stack:23040 pid:11465 ppid:3638 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irq+0x3c/0x40 kernel/locking/spinlock.c:202 spin_unlock_irq include/linux/spinlock.h:401 [inline] loop_queue_work drivers/block/loop.c:894 [inline] loop_queue_rq+0x9d9/0xac0 drivers/block/loop.c:1874 __blk_mq_issue_directly block/blk-mq.c:2631 [inline] __blk_mq_try_issue_directly+0x4ab/0x7a0 block/blk-mq.c:2684 blk_mq_request_issue_directly block/blk-mq.c:2718 [inline] blk_mq_plug_issue_direct+0x233/0x620 block/blk-mq.c:2738 blk_mq_flush_plug_list+0x7e7/0xd40 block/blk-mq.c:2838 __blk_flush_plug+0x3c6/0x440 block/blk-core.c:1179 blk_finish_plug+0x59/0x80 block/blk-core.c:1203 read_pages+0x646/0x840 mm/readahead.c:184 page_cache_ra_unbounded+0x690/0x770 mm/readahead.c:270 do_page_cache_ra mm/readahead.c:300 [inline] force_page_cache_ra mm/readahead.c:331 [inline] page_cache_sync_ra+0x3d7/0x490 mm/readahead.c:713 page_cache_sync_readahead include/linux/pagemap.h:1248 [inline] filemap_get_pages mm/filemap.c:2665 [inline] filemap_read+0x5ff/0x2f80 mm/filemap.c:2759 blkdev_read_iter+0x3d5/0x500 block/fops.c:614 call_read_iter include/linux/fs.h:2259 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x434/0x920 fs/read_write.c:470 ksys_read+0x143/0x240 fs/read_write.c:613 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fd3076a7407 RSP: 002b:00007ffd95c28b00 EFLAGS: 00000202 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007fd307d90880 RCX: 00007fd3076a7407 RDX: 0000000000000200 RSI: 00007fd307d82000 RDI: 0000000000000009 RBP: 00005637e99e4f80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 0000000000009000 R14: 00005637e99d3338 R15: 00007fd307e5539c rcu: rcu_preempt kthread starved for 9752 jiffies! g96625 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:27424 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 schedule+0xb9/0x180 kernel/sched/core.c:6637 schedule_timeout+0x15c/0x280 kernel/time/timer.c:2167 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline] NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline] NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:741