bisecting cause commit starting from f21b807c3cf8cd7c5ca9e406b27bf1cd2f1c1238 building syzkaller on 1ba81399e2d03b53a7e631c4ab05f25af1fb1911 testing commit f21b807c3cf8cd7c5ca9e406b27bf1cd2f1c1238 with gcc (GCC) 10.2.1 20210217 kernel signature: 49df713f97d3da932778186e1310bc29b4c9a7f08145108b009a80abe534721e all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.12 testing commit 9f4ad9e425a1d3b6a34617b8ea226d56a119a717 with gcc (GCC) 10.2.1 20210217 kernel signature: 20a3195b0c2adea39c30d2e9f830a6fa425a34f031f28cd84a5fc4bf09ce8f4d all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.11 testing commit f40ddce88593482919761f74910f42f4b84c004b with gcc (GCC) 10.2.1 20210217 kernel signature: 22b26ae1e3be417e2ad324e47433a262e845b6471dfc09f4fa2f647b3330df8e all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.10 testing commit 2c85ebc57b3e1817b6ce1a6b703928e113a90442 with gcc (GCC) 10.2.1 20210217 kernel signature: 8f55ba93fd53951cac9b68b979c728becbef461543abacbe99727324ff41baf6 all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.9 testing commit bbf5c979011a099af5dc76498918ed7df445635b with gcc (GCC) 10.2.1 20210217 kernel signature: f654d07eeb7c456b884d4afbd5bc4d393d1b1677ed42327eee0eaef482a1d4de all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.8 testing commit bcf876870b95592b52519ed4aafcf9d95999bc9c with gcc (GCC) 8.4.1 20210217 kernel signature: 1063ebaf54671db7804acf12269942e9a5933d00bfb78bb5cf898a218f3c1d07 all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.7 testing commit 3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162 with gcc (GCC) 8.4.1 20210217 kernel signature: 3856a09b3d94850025e3ae49dd0f33b972955333e09df445983a6a278d85997d all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.6 testing commit 7111951b8d4973bda27ff663f2cf18b663d15b48 with gcc (GCC) 8.4.1 20210217 kernel signature: a3b93acd1315ac27fd28df3f64d6ec371b03ab2c3dca6caf01eeb51039157802 all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.5 testing commit d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 with gcc (GCC) 8.4.1 20210217 kernel signature: 56b75590080ebce41771eb20fb3a18a21250479d609f5cd866a9e9cf93705477 all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.4.1 20210217 kernel signature: c6858008ba2dd87e1e0dfa3f7b77c43b09b0dc43a2a0142524db4f19e9503c6e all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.4.1 20210217 kernel signature: aae18b99c108d4b86fb7c39080c3a8373862416e546d19d54d8a47dcb2701455 all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.4.1 20210217 kernel signature: e13f671b39135f0fd02c29412f7240f2d07a062c4a49e605a3f48631956d18cb all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.4.1 20210217 kernel signature: 1e42e1e588ea7d5fe6accbe13bfa4221a4f9f3d4fb725780ca1567cc27b907dc all runs: crashed: INFO: task hung in ext4_fill_super testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.4.1 20210217 kernel signature: 456ab9d42a47fc3d91f08b7c50f5c4ec701f7eb218a74b092e90c30f2478d7da all runs: crashed: INFO: task hung in ext4_fill_super testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.4.1 20210217 kernel signature: 850896a75a5db14fde15a59232200efba55a559fd5e8ae4554cbd6efab6ca42c all runs: crashed: INFO: task hung in ext4_fill_super testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.4.1 20210217 kernel signature: 5d6f5f6ad87c34f16c4f2fa77937a265bf09879eda24ffa695198833c29f28d1 all runs: crashed: INFO: task hung in ext4_fill_super testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.4.1 20210217 kernel signature: 436c6ce5a895a7df5f780ac1dd68518714f57b0088bc9ed223ce6911afceaefe all runs: crashed: INFO: task hung in ext4_fill_super testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.4.1 20210217 failed to run ["make" "-j" "64" "ARCH=x86_64" "CC=/syzkaller/shared/bisect_bin/gcc-8.1.0/bin/gcc" "bzImage"]: exit status 2 testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.4.1 20210217 orc_dump.c:106:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] orc_dump.c:111:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] elf.c:135:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:140:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.4.1 20210217 orc_dump.c:106:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] orc_dump.c:111:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] elf.c:135:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:140:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] pager.c:36:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.4.1 20210217 orc_dump.c:105:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] orc_dump.c:110:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] elf.c:134:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:139:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] pager.c:36:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.4.1 20210217 pager.c:35:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] elf.c:144:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:149:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.4.1 20210217 pager.c:35:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] elf.c:141:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:146:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.5.0 elf.c:141:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:146:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] pager.c:35:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 tools/include/linux/log2.h:19:1: error: ignoring attribute 'noreturn' because it conflicts with attribute 'const' [-Werror=attributes] elf.c:129:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:134:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] pager.c:35:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 tools/include/linux/log2.h:19:1: error: ignoring attribute 'noreturn' because it conflicts with attribute 'const' [-Werror=attributes] pager.c:35:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] elf.c:129:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:134:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 tools/include/linux/log2.h:19:1: error: ignoring attribute 'noreturn' because it conflicts with attribute 'const' [-Werror=attributes] elf.c:129:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:134:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] pager.c:33:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 tools/include/linux/log2.h:19:1: error: ignoring attribute 'noreturn' because it conflicts with attribute 'const' [-Werror=attributes] elf.c:122:2: error: 'elf_getshnum' is deprecated [-Werror=deprecated-declarations] elf.c:127:2: error: 'elf_getshstrndx' is deprecated [-Werror=deprecated-declarations] pager.c:33:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 tools/include/linux/log2.h:19:1: error: ignoring attribute 'noreturn' because it conflicts with attribute 'const' [-Werror=attributes] pager.c:33:12: error: passing argument 2 to 'restrict'-qualified parameter aliases with argument 4 [-Werror=restrict] revisions tested: 17, total time: 3h38m26.220105933s (build: 1h55m10.006313457s, test: 1h37m19.980062132s) the crash already happened on the oldest tested release commit msg: Linux 4.18 crash: INFO: task hung in ext4_fill_super Bluetooth: hci3: command 0x0406 tx timeout Bluetooth: hci4: command 0x0406 tx timeout Bluetooth: hci5: command 0x0406 tx timeout NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 INFO: task syz-executor.5:10063 blocked for more than 140 seconds. Not tainted 4.18.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D27480 10063 8570 0x00080004 Call Trace: context_switch kernel/sched/core.c:2853 [inline] __schedule+0x80c/0x1fc0 kernel/sched/core.c:3501 schedule+0x7f/0x1b0 kernel/sched/core.c:3545 schedule_timeout+0x70e/0xd20 kernel/time/timer.c:1777 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x3fb/0x5d0 kernel/sched/completion.c:115 wait_for_completion+0x18/0x20 kernel/sched/completion.c:136 kthread_stop+0xc9/0x550 kernel/kthread.c:548 ext4_fill_super+0x71af/0xaf00 fs/ext4/super.c:4497 mount_bdev+0x26f/0x330 fs/super.c:1174 ext4_mount+0x10/0x20 fs/ext4/super.c:5839 mount_fs+0x7f/0x2a9 fs/super.c:1277 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2542 [inline] do_mount+0x376/0x2710 fs/namespace.c:2872 ksys_mount+0xb1/0xd0 fs/namespace.c:3088 __do_sys_mount fs/namespace.c:3102 [inline] __se_sys_mount fs/namespace.c:3099 [inline] __x64_sys_mount+0xb9/0x150 fs/namespace.c:3099 do_syscall_64+0xda/0x540 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x467afa Code: 4c 8b 84 24 90 01 00 00 4c 8b 4c 24 50 4d 89 0c d8 e9 00 ff ff ff 48 89 44 24 58 48 89 94 24 60 01 00 00 48 8d 05 86 ee 1d 00 <48> 89 04 24 48 8b 8c 24 90 01 00 00 48 89 4c 24 08 48 89 5c 24 10 RSP: 002b:00007fd9c5e1cfa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007fd9c5e1d000 RBP: 00007fd9c5e1d040 R08: 00007fd9c5e1d040 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000 R13: 00000000200000c0 R14: 00007fd9c5e1d000 R15: 0000000020000200 INFO: task syz-executor.1:10085 blocked for more than 140 seconds. Not tainted 4.18.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D27480 10085 8566 0x00080004 Call Trace: context_switch kernel/sched/core.c:2853 [inline] __schedule+0x80c/0x1fc0 kernel/sched/core.c:3501 schedule+0x7f/0x1b0 kernel/sched/core.c:3545 schedule_timeout+0x70e/0xd20 kernel/time/timer.c:1777 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x3fb/0x5d0 kernel/sched/completion.c:115 wait_for_completion+0x18/0x20 kernel/sched/completion.c:136 kthread_stop+0xc9/0x550 kernel/kthread.c:548 ext4_fill_super+0x71af/0xaf00 fs/ext4/super.c:4497 mount_bdev+0x26f/0x330 fs/super.c:1174 ext4_mount+0x10/0x20 fs/ext4/super.c:5839 mount_fs+0x7f/0x2a9 fs/super.c:1277 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2542 [inline] do_mount+0x376/0x2710 fs/namespace.c:2872 ksys_mount+0xb1/0xd0 fs/namespace.c:3088 __do_sys_mount fs/namespace.c:3102 [inline] __se_sys_mount fs/namespace.c:3099 [inline] __x64_sys_mount+0xb9/0x150 fs/namespace.c:3099 do_syscall_64+0xda/0x540 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x467afa Code: 4c 8b 84 24 90 01 00 00 4c 8b 4c 24 50 4d 89 0c d8 e9 00 ff ff ff 48 89 44 24 58 48 89 94 24 60 01 00 00 48 8d 05 86 ee 1d 00 <48> 89 04 24 48 8b 8c 24 90 01 00 00 48 89 4c 24 08 48 89 5c 24 10 RSP: 002b:00007f7e872f7fa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007f7e872f8000 RBP: 00007f7e872f8040 R08: 00007f7e872f8040 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000 R13: 00000000200000c0 R14: 00007f7e872f8000 R15: 0000000020000200 INFO: task syz-executor.2:10120 blocked for more than 140 seconds. Not tainted 4.18.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27480 10120 8562 0x00080004 Call Trace: context_switch kernel/sched/core.c:2853 [inline] __schedule+0x80c/0x1fc0 kernel/sched/core.c:3501 schedule+0x7f/0x1b0 kernel/sched/core.c:3545 schedule_timeout+0x70e/0xd20 kernel/time/timer.c:1777 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x3fb/0x5d0 kernel/sched/completion.c:115 wait_for_completion+0x18/0x20 kernel/sched/completion.c:136 kthread_stop+0xc9/0x550 kernel/kthread.c:548 ext4_fill_super+0x71af/0xaf00 fs/ext4/super.c:4497 mount_bdev+0x26f/0x330 fs/super.c:1174 ext4_mount+0x10/0x20 fs/ext4/super.c:5839 mount_fs+0x7f/0x2a9 fs/super.c:1277 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2542 [inline] do_mount+0x376/0x2710 fs/namespace.c:2872 ksys_mount+0xb1/0xd0 fs/namespace.c:3088 __do_sys_mount fs/namespace.c:3102 [inline] __se_sys_mount fs/namespace.c:3099 [inline] __x64_sys_mount+0xb9/0x150 fs/namespace.c:3099 do_syscall_64+0xda/0x540 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x467afa Code: 4c 8b 84 24 90 01 00 00 4c 8b 4c 24 50 4d 89 0c d8 e9 00 ff ff ff 48 89 44 24 58 48 89 94 24 60 01 00 00 48 8d 05 86 ee 1d 00 <48> 89 04 24 48 8b 8c 24 90 01 00 00 48 89 4c 24 08 48 89 5c 24 10 RSP: 002b:00007f2fa8446fa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007f2fa8447000 RBP: 00007f2fa8447040 R08: 00007f2fa8447040 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000 R13: 00000000200000c0 R14: 00007f2fa8447000 R15: 0000000020000200 INFO: task syz-executor.0:10151 blocked for more than 140 seconds. Not tainted 4.18.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D27480 10151 8571 0x00080004 Call Trace: context_switch kernel/sched/core.c:2853 [inline] __schedule+0x80c/0x1fc0 kernel/sched/core.c:3501 schedule+0x7f/0x1b0 kernel/sched/core.c:3545 schedule_timeout+0x70e/0xd20 kernel/time/timer.c:1777 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x3fb/0x5d0 kernel/sched/completion.c:115 wait_for_completion+0x18/0x20 kernel/sched/completion.c:136 kthread_stop+0xc9/0x550 kernel/kthread.c:548 ext4_fill_super+0x71af/0xaf00 fs/ext4/super.c:4497 mount_bdev+0x26f/0x330 fs/super.c:1174 ext4_mount+0x10/0x20 fs/ext4/super.c:5839 mount_fs+0x7f/0x2a9 fs/super.c:1277 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2542 [inline] do_mount+0x376/0x2710 fs/namespace.c:2872 ksys_mount+0xb1/0xd0 fs/namespace.c:3088 __do_sys_mount fs/namespace.c:3102 [inline] __se_sys_mount fs/namespace.c:3099 [inline] __x64_sys_mount+0xb9/0x150 fs/namespace.c:3099 do_syscall_64+0xda/0x540 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x467afa Code: 4c 8b 84 24 90 01 00 00 4c 8b 4c 24 50 4d 89 0c d8 e9 00 ff ff ff 48 89 44 24 58 48 89 94 24 60 01 00 00 48 8d 05 86 ee 1d 00 <48> 89 04 24 48 8b 8c 24 90 01 00 00 48 89 4c 24 08 48 89 5c 24 10 RSP: 002b:00007fc0229b0fa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007fc0229b1000 RBP: 00007fc0229b1040 R08: 00007fc0229b1040 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000 R13: 00000000200000c0 R14: 00007fc0229b1000 R15: 0000000020000200 Showing all locks held in the system: 1 lock held by khungtaskd/1509: #0: 0000000014eb75fa (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4461 1 lock held by in:imklog/7863: #0: 00000000e997430e (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:766 1 lock held by syz-executor.5/10063: #0: 00000000a9a8c9f9 (&type->s_umount_key#25/1){+.+.}, at: alloc_super fs/super.c:223 [inline] #0: 00000000a9a8c9f9 (&type->s_umount_key#25/1){+.+.}, at: sget_userns+0x1a1/0xb60 fs/super.c:516 1 lock held by syz-executor.1/10085: #0: 00000000031db7ef (&type->s_umount_key#25/1){+.+.}, at: alloc_super fs/super.c:223 [inline] #0: 00000000031db7ef (&type->s_umount_key#25/1){+.+.}, at: sget_userns+0x1a1/0xb60 fs/super.c:516 1 lock held by syz-executor.2/10120: #0: 00000000dd4cb7df (&type->s_umount_key#25/1){+.+.}, at: alloc_super fs/super.c:223 [inline] #0: 00000000dd4cb7df (&type->s_umount_key#25/1){+.+.}, at: sget_userns+0x1a1/0xb60 fs/super.c:516 1 lock held by syz-executor.0/10151: #0: 0000000077a2d79d (&type->s_umount_key#25/1){+.+.}, at: alloc_super fs/super.c:223 [inline] #0: 0000000077a2d79d (&type->s_umount_key#25/1){+.+.}, at: sget_userns+0x1a1/0xb60 fs/super.c:516 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1509 Comm: khungtaskd Not tainted 4.18.0-syzkaller #0 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+0x15a/0x20d lib/dump_stack.c:113 nmi_cpu_backtrace.cold.0+0x13/0xb6 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0xf6/0x11a lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline] watchdog+0x512/0x940 kernel/hung_task.c:252 kthread+0x316/0x3d0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54