bisecting fixing commit since ef244c3088856cf048c77231653b4c92a7b2213c building syzkaller on a41ca8fa8285754d8561dcc3ed54cca2da60eed7 testing commit ef244c3088856cf048c77231653b4c92a7b2213c with gcc (GCC) 8.1.0 kernel signature: d4817a943c05d7a02b2f0e8e39908b7160720bd6 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 sys_open run #5: crashed: INFO: rcu detected stall in ext4_file_read_iter run #6: crashed: INFO: rcu detected stall in sys_open run #7: crashed: INFO: rcu detected stall in sys_open run #8: crashed: INFO: rcu detected stall in ext4_file_read_iter run #9: crashed: INFO: rcu detected stall in corrupted testing current HEAD 312017a460d5ea31d646e7148e400e13db799ddc testing commit 312017a460d5ea31d646e7148e400e13db799ddc with gcc (GCC) 8.1.0 kernel signature: 38dd1d641b88a02faf6cebb032a8666a2989d021 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 ext4_file_read_iter 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 ext4_file_read_iter run #6: crashed: INFO: rcu detected stall in sys_open run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in ext4_file_read_iter run #9: crashed: INFO: rcu detected stall in corrupted revisions tested: 2, total time: 27m35.569488235s (build: 16m53.420218493s, test: 10m4.23732694s) the crash still happens on HEAD commit msg: Linux 4.19.89 crash: INFO: rcu detected stall in corrupted audit: type=1800 audit(1576299533.591:43): pid=7034 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op=collect_data cause=failed comm="syz-executor.4" name="bus" dev="sda1" ino=16523 res=0 IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready hrtimer: interrupt took 49436 ns rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7039 rcu: (detected by 0, t=10503 jiffies, g=4901, q=279) udevd R running task 28216 7039 3592 0x00000000 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 preempt_schedule_notrace+0x70/0x140 kernel/sched/core.c:3713 ___preempt_schedule_notrace+0x16/0x2d rcu_is_watching+0x23/0x30 kernel/rcu/tree.c:1026 rcu_read_unlock include/linux/rcupdate.h:677 [inline] is_bpf_text_address+0x8a/0xe0 kernel/bpf/core.c:547 kernel_text_address+0x79/0xf0 kernel/extable.c:152 __kernel_text_address+0xd/0x40 kernel/extable.c:107 unwind_get_return_address+0x61/0xa0 arch/x86/kernel/unwind_frame.c:18 __save_stack_trace+0x9c/0x100 arch/x86/kernel/stacktrace.c:45 save_stack_trace+0x1a/0x20 arch/x86/kernel/stacktrace.c:60 save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc mm/slab.c:3397 [inline] kmem_cache_alloc+0x11b/0x730 mm/slab.c:3557 anon_vma_chain_alloc mm/rmap.c:129 [inline] anon_vma_clone+0xc3/0x3f0 mm/rmap.c:269 anon_vma_fork+0x80/0x450 mm/rmap.c:332 dup_mmap kernel/fork.c:494 [inline] dup_mm kernel/fork.c:1278 [inline] copy_mm kernel/fork.c:1334 [inline] copy_process.part.35+0x3a76/0x7330 kernel/fork.c:1887 copy_process kernel/fork.c:1684 [inline] _do_fork+0x15d/0xba0 kernel/fork.c:2197 __do_sys_clone kernel/fork.c:2304 [inline] __se_sys_clone kernel/fork.c:2298 [inline] __x64_sys_clone+0xba/0x140 kernel/fork.c:2298 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fc848ea5f46 Code: Bad RIP value. RSP: 002b:00007fff5e8858c0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fff5e8858c0 RCX: 00007fc848ea5f46 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007fff5e885920 R08: 0000000000001b7f R09: 0000000000001b7f R10: 00007fc8497c2a70 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff5e8858e0 R14: 0000000000000005 R15: 0000000000000005 udevd R running task 28216 7039 3592 0x00000000 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 preempt_schedule_notrace+0x70/0x140 kernel/sched/core.c:3713 ___preempt_schedule_notrace+0x16/0x2d rcu_is_watching+0x23/0x30 kernel/rcu/tree.c:1026 rcu_read_unlock include/linux/rcupdate.h:677 [inline] is_bpf_text_address+0x8a/0xe0 kernel/bpf/core.c:547 kernel_text_address+0x79/0xf0 kernel/extable.c:152 __kernel_text_address+0xd/0x40 kernel/extable.c:107 unwind_get_return_address+0x61/0xa0 arch/x86/kernel/unwind_frame.c:18 __save_stack_trace+0x9c/0x100 arch/x86/kernel/stacktrace.c:45 save_stack_trace+0x1a/0x20 arch/x86/kernel/stacktrace.c:60 save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc mm/slab.c:3397 [inline] kmem_cache_alloc+0x11b/0x730 mm/slab.c:3557 anon_vma_chain_alloc mm/rmap.c:129 [inline] anon_vma_clone+0xc3/0x3f0 mm/rmap.c:269 anon_vma_fork+0x80/0x450 mm/rmap.c:332 dup_mmap kernel/fork.c:494 [inline] dup_mm kernel/fork.c:1278 [inline] copy_mm kernel/fork.c:1334 [inline] copy_process.part.35+0x3a76/0x7330 kernel/fork.c:1887 copy_process kernel/fork.c:1684 [inline] _do_fork+0x15d/0xba0 kernel/fork.c:2197 __do_sys_clone kernel/fork.c:2304 [inline] __se_sys_clone kernel/fork.c:2298 [inline] __x64_sys_clone+0xba/0x140 kernel/fork.c:2298 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fc848ea5f46 Code: Bad RIP value. RSP: 002b:00007fff5e8858c0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fff5e8858c0 RCX: 00007fc848ea5f46 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007fff5e885920 R08: 0000000000001b7f R09: 0000000000001b7f R10: 00007fc8497c2a70 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff5e8858e0 R14: 0000000000000005 R15: 0000000000000005 rcu: rcu_preempt kthread starved for 10564 jiffies! g4901 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29208 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+0xcf8/0x23d0 kernel/rcu/tree.c:2202 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415