bisecting fixing commit since ef244c3088856cf048c77231653b4c92a7b2213c building syzkaller on a41ca8fa8285754d8561dcc3ed54cca2da60eed7 testing commit ef244c3088856cf048c77231653b4c92a7b2213c with gcc (GCC) 8.1.0 kernel signature: ef57df95a2de10dedc333ca4b047c636b1b988691554b10f77e73a2a1f0ca0cf run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in sys_open run #2: crashed: INFO: rcu detected stall in sys_open run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in ext4_file_read_iter run #5: crashed: INFO: rcu detected stall in sys_open run #6: crashed: INFO: rcu detected stall in corrupted run #7: crashed: INFO: rcu detected stall in ext4_file_read_iter run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in sys_open testing current HEAD 3fc898571b974f9a05e4e5c1fe17b18548207091 testing commit 3fc898571b974f9a05e4e5c1fe17b18548207091 with gcc (GCC) 8.1.0 kernel signature: 3a492701bb407cba058bfbbef45bba785e4a78a5b5960f814dd9cdde1e5f0fbc run #0: crashed: INFO: rcu detected stall in sys_open run #1: crashed: INFO: rcu detected stall in ext4_file_read_iter run #2: crashed: INFO: rcu detected stall in sys_open run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in sys_open run #6: crashed: INFO: rcu detected stall in corrupted run #7: crashed: INFO: rcu detected stall in sys_open run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in corrupted revisions tested: 2, total time: 31m7.545046011s (build: 17m30.071199263s, test: 12m55.843853844s) the crash still happens on HEAD commit msg: Linux 4.19.128 crash: INFO: rcu detected stall in corrupted audit: type=1800 audit(1591866929.949:28): pid=7340 uid=0 auid=0 ses=8 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed comm="syz-executor.5" name="bus" dev="sda1" ino=15787 res=0 audit: type=1800 audit(1591866931.790:29): pid=7351 uid=0 auid=0 ses=8 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed comm="syz-executor.4" name="bus" dev="sda1" ino=15790 res=0 rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7359 rcu: (detected by 1, t=10502 jiffies, g=5997, q=178) syz-executor.5 R running task 28136 7359 6387 0x00000000 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 preempt_schedule_irq+0x87/0x110 kernel/sched/core.c:3742 retint_kernel+0x1b/0x2d RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:lock_is_held_type+0x18b/0x210 kernel/locking/lockdep.c:3947 Code: ff df 41 c7 84 24 84 08 00 00 00 00 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 75 63 48 83 3d 94 51 a7 06 00 74 30 48 89 df 57 9d <0f> 1f 44 00 00 48 83 c4 08 44 89 e8 5b 41 5c 41 5d 5d c3 48 83 c4 RSP: 0000:ffff88808eeb7a28 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 0000000000000286 RCX: ffffffff8151bd91 RDX: 1ffffffff0fe4111 RSI: ffffffff87fbc420 RDI: 0000000000000286 RBP: ffff88808eeb7a48 R08: ffffed1015d64733 R09: ffffed1015d64732 R10: ffffed1015d64732 R11: ffff8880aeb23993 R12: ffff88808f744480 R13: 0000000000000000 R14: 0000000000000000 R15: ffffea000201bbc0 lock_is_held include/linux/lockdep.h:344 [inline] task_css include/linux/cgroup.h:483 [inline] blk_cgroup_congested include/linux/blk-cgroup.h:259 [inline] mem_cgroup_throttle_swaprate+0x1df/0x585 mm/swapfile.c:3748 mem_cgroup_try_charge_delay+0x6a/0xa0 mm/memcontrol.c:6016 wp_page_copy+0x3b5/0x10b0 mm/memory.c:2520 do_wp_page+0x1c8/0xf40 mm/memory.c:2799 handle_pte_fault mm/memory.c:4057 [inline] __handle_mm_fault+0x1a4f/0x3230 mm/memory.c:4165 handle_mm_fault+0x36b/0x8d0 mm/memory.c:4202 __do_page_fault+0x466/0xb20 arch/x86/mm/fault.c:1412 do_page_fault+0x64/0x3a7 arch/x86/mm/fault.c:1487 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1205 RIP: 0033:0x431026 Code: 1f 44 00 00 48 29 e8 31 c9 48 81 fb 40 66 71 00 0f 95 c1 48 8d 34 2a 48 83 cd 01 48 c1 e1 02 48 83 c8 01 48 09 e9 48 89 73 58 <48> 89 4a 08 48 89 46 08 48 8d 4a 10 8b 05 bc 5c 64 00 85 c0 0f 84 RSP: 002b:00007ffd66bc4450 EFLAGS: 00010206 RAX: 00000000000205b1 RBX: 0000000000716640 RCX: 0000000000000121 RDX: 000000000159c930 RSI: 000000000159ca50 RDI: 0000000000000000 RBP: 0000000000000121 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000716698 R13: 0000000000716698 R14: 0000000000000000 R15: 0000000000002710 syz-executor.5 R running task 28136 7359 6387 0x00000000 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 preempt_schedule_irq+0x87/0x110 kernel/sched/core.c:3742 retint_kernel+0x1b/0x2d RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:lock_is_held_type+0x18b/0x210 kernel/locking/lockdep.c:3947 Code: ff df 41 c7 84 24 84 08 00 00 00 00 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 75 63 48 83 3d 94 51 a7 06 00 74 30 48 89 df 57 9d <0f> 1f 44 00 00 48 83 c4 08 44 89 e8 5b 41 5c 41 5d 5d c3 48 83 c4 RSP: 0000:ffff88808eeb7a28 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 0000000000000286 RCX: ffffffff8151bd91 RDX: 1ffffffff0fe4111 RSI: ffffffff87fbc420 RDI: 0000000000000286 RBP: ffff88808eeb7a48 R08: ffffed1015d64733 R09: ffffed1015d64732 R10: ffffed1015d64732 R11: ffff8880aeb23993 R12: ffff88808f744480 R13: 0000000000000000 R14: 0000000000000000 R15: ffffea000201bbc0 lock_is_held include/linux/lockdep.h:344 [inline] task_css include/linux/cgroup.h:483 [inline] blk_cgroup_congested include/linux/blk-cgroup.h:259 [inline] mem_cgroup_throttle_swaprate+0x1df/0x585 mm/swapfile.c:3748 mem_cgroup_try_charge_delay+0x6a/0xa0 mm/memcontrol.c:6016 wp_page_copy+0x3b5/0x10b0 mm/memory.c:2520 do_wp_page+0x1c8/0xf40 mm/memory.c:2799 handle_pte_fault mm/memory.c:4057 [inline] __handle_mm_fault+0x1a4f/0x3230 mm/memory.c:4165 handle_mm_fault+0x36b/0x8d0 mm/memory.c:4202 __do_page_fault+0x466/0xb20 arch/x86/mm/fault.c:1412 do_page_fault+0x64/0x3a7 arch/x86/mm/fault.c:1487 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1205 RIP: 0033:0x431026 Code: 1f 44 00 00 48 29 e8 31 c9 48 81 fb 40 66 71 00 0f 95 c1 48 8d 34 2a 48 83 cd 01 48 c1 e1 02 48 83 c8 01 48 09 e9 48 89 73 58 <48> 89 4a 08 48 89 46 08 48 8d 4a 10 8b 05 bc 5c 64 00 85 c0 0f 84 RSP: 002b:00007ffd66bc4450 EFLAGS: 00010206 RAX: 00000000000205b1 RBX: 0000000000716640 RCX: 0000000000000121 RDX: 000000000159c930 RSI: 000000000159ca50 RDI: 0000000000000000 RBP: 0000000000000121 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000716698 R13: 0000000000716698 R14: 0000000000000000 R15: 0000000000002710 rcu: rcu_preempt kthread starved for 10502 jiffies! g5997 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29608 10 2 0x80000000 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 schedule+0x7f/0x1b0 kernel/sched/core.c:3559 schedule_timeout+0x3ab/0xda0 kernel/time/timer.c:1806 rcu_gp_kthread+0xce6/0x23d0 kernel/rcu/tree.c:2202 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415