bisecting fixing commit since 6fbc7275c7a9ba97877050335f290341a1fd8dbf building syzkaller on cccc4302d7da39e2fc41f9275442c267935632b7 testing commit 6fbc7275c7a9ba97877050335f290341a1fd8dbf with gcc (GCC) 8.1.0 kernel signature: cc5f2a79285866a8cecc46a64625a81fda18130a all runs: crashed: INFO: task hung in blkdev_issue_flush testing current HEAD 9455d25f4e3b3d009fa1b810862e5b06229530e4 testing commit 9455d25f4e3b3d009fa1b810862e5b06229530e4 with gcc (GCC) 8.1.0 kernel signature: e2f413b4490a9206efddcbd8ebee7970fe47d2ab all runs: crashed: INFO: task hung in blkdev_issue_flush revisions tested: 2, total time: 24m56.244550384s (build: 12m16.636424985s, test: 11m46.538808187s) the crash still happens on HEAD commit msg: Merge tag 'ntb-5.5' of git://github.com/jonmason/ntb crash: INFO: task hung in blkdev_issue_flush INFO: task syz-executor.2:7582 blocked for more than 143 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27536 7582 7522 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007f46369a5c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f46369a66d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff INFO: task syz-executor.2:7607 blocked for more than 143 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D29520 7607 7522 0x00000004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007f4636963c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f46369646d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff INFO: task syz-executor.1:7588 blocked for more than 143 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28680 7588 7516 0x00000004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007fd0a9f1ec78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd0a9f1f6d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff INFO: task syz-executor.4:7592 blocked for more than 144 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D27536 7592 7526 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007f945f50ec78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f945f50f6d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff INFO: task syz-executor.0:7596 blocked for more than 144 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D27536 7596 7521 0x00000004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007f0aa8302c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0aa83036d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff INFO: task syz-executor.0:7613 blocked for more than 144 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D29520 7613 7521 0x00000004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007f0aa82c0c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0aa82c16d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff INFO: task syz-executor.3:7600 blocked for more than 145 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28680 7600 7519 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007f0716bf9c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0716bfa6d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff INFO: task syz-executor.3:7615 blocked for more than 145 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D29520 7615 7519 0x00000004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007f0716bb7c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0716bb86d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff INFO: task syz-executor.5:7605 blocked for more than 145 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D28680 7605 7525 0x00000004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1900 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x5c4/0xad0 kernel/time/timer.c:1871 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5787 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common_io kernel/sched/completion.c:121 [inline] wait_for_completion_io+0x28b/0x460 kernel/sched/completion.c:169 submit_bio_wait+0x110/0x1b0 block/bio.c:976 blkdev_issue_flush+0x1e3/0x2c0 block/blk-flush.c:472 blkdev_fsync+0x70/0xc0 fs/block_dev.c:675 vfs_fsync_range+0xee/0x220 fs/sync.c:197 vfs_fsync fs/sync.c:211 [inline] do_fsync+0x38/0x70 fs/sync.c:221 __do_sys_fdatasync fs/sync.c:234 [inline] __se_sys_fdatasync fs/sync.c:232 [inline] __x64_sys_fdatasync+0x31/0x40 fs/sync.c:232 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: 10 48 89 4c 24 18 e8 c6 d9 ff ff 0f b6 4c 24 20 48 8b 44 24 38 48 8b 54 24 40 eb a2 31 c9 eb 9e 48 89 1c 24 48 89 4c 24 08 48 <89> 7c 24 10 48 89 74 24 18 e8 99 d9 ff ff 0f b6 4c 24 20 48 8b 44 RSP: 002b:00007f122dbeec78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004597c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f122dbef6d4 R13: 00000000004c005d R14: 00000000004d1e50 R15: 00000000ffffffff Showing all locks held in the system: 3 locks held by kworker/u4:0/7: #0: ffff8880aec37298 (&rq->lock){-.-.}, at: newidle_balance+0x9df/0xe70 kernel/sched/fair.c:10166 #1: ffffffff8859c480 (rcu_read_lock){....}, at: __update_idle_core+0x45/0x3f0 kernel/sched/fair.c:5729 #2: ffff8880aec27258 (&base->lock){..-.}, at: lock_timer_base+0xc8/0x160 kernel/time/timer.c:936 1 lock held by khungtaskd/1059: #0: ffffffff8859c480 (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x275 kernel/locking/lockdep.c:5334 2 locks held by getty/7405: #0: ffff8880a113e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f252e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7406: #0: ffff888097cc5090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f192e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7407: #0: ffff8880a82eb090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f1d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7408: #0: ffff8880a8670090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f0d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7409: #0: ffff88809128f090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f152e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7410: #0: ffff8880959c5090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f292e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7411: #0: ffff88809a353090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005ef12e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x17d0 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1059 Comm: khungtaskd Not tainted 5.4.0-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+0x12d/0x187 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.7+0x4b/0x84 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x18b/0x1b7 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0x611/0xc50 kernel/hung_task.c:289 kthread+0x331/0x3f0 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:60