bisecting fixing commit since a1b977b49b66c75e6c51a515f6700371ae720217 building syzkaller on fc7735a27949755327024847e12dcc1b868bcb99 testing commit a1b977b49b66c75e6c51a515f6700371ae720217 with gcc (GCC) 8.1.0 kernel signature: ff2f03e42741b6dea9f9dc129d5ddfc8ee47ea65c3be242459d9adeae2a85867 run #0: crashed: INFO: task hung in __blkdev_get run #1: crashed: INFO: task hung in do_read_cache_page run #2: crashed: INFO: task hung in do_read_cache_page run #3: crashed: INFO: task hung in do_read_cache_page run #4: crashed: INFO: task hung in __blkdev_get run #5: crashed: INFO: task hung in do_read_cache_page run #6: crashed: INFO: task hung in do_read_cache_page run #7: crashed: INFO: task hung in do_read_cache_page run #8: crashed: INFO: task hung in do_read_cache_page run #9: crashed: INFO: task hung in do_read_cache_page testing current HEAD 31acccdc877486a649a86d37725a15175fcd5ed6 testing commit 31acccdc877486a649a86d37725a15175fcd5ed6 with gcc (GCC) 8.1.0 kernel signature: af754259e1669300c0e0c0bdffaaa50b24c42d2906f91adc2eaaf31702de1c4c run #0: crashed: INFO: task hung in blkdev_put run #1: crashed: INFO: task hung in do_read_cache_page run #2: crashed: INFO: task hung in do_read_cache_page run #3: crashed: INFO: task hung in blkdev_put run #4: crashed: INFO: task hung in do_read_cache_page run #5: crashed: INFO: task hung in do_read_cache_page run #6: crashed: INFO: task hung in do_read_cache_page run #7: crashed: INFO: task hung in blkdev_put run #8: crashed: INFO: task hung in do_read_cache_page run #9: crashed: INFO: task hung in do_read_cache_page revisions tested: 2, total time: 33m33.301712374s (build: 18m49.066662198s, test: 14m0.869275767s) the crash still happens on HEAD commit msg: Linux 4.19.157 crash: INFO: task hung in do_read_cache_page Dev nbd0: unable to read RDB block 0 nbd0: unable to read partition table ldm_validate_partition_table(): Disk read failed. Dev nbd0: unable to read RDB block 0 nbd0: unable to read partition table INFO: task systemd-udevd:8217 blocked for more than 140 seconds. Not tainted 4.19.157-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. systemd-udevd D25464 8217 3732 0x00000100 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 io_schedule+0x1c/0x70 kernel/sched/core.c:5185 wait_on_page_bit_common mm/filemap.c:1123 [inline] wait_on_page_bit+0x1c1/0x360 mm/filemap.c:1156 wait_on_page_locked include/linux/pagemap.h:530 [inline] wait_on_page_read mm/filemap.c:2795 [inline] do_read_cache_page.part.5+0x32b/0xc90 mm/filemap.c:2834 do_read_cache_page include/linux/pagemap.h:102 [inline] read_cache_page+0x40/0x70 mm/filemap.c:2924 read_mapping_page include/linux/pagemap.h:402 [inline] read_dev_sector+0xbd/0x430 block/partition-generic.c:671 read_part_sector block/partitions/check.h:38 [inline] adfspart_check_ICS+0x109/0xd30 block/partitions/acorn.c:366 check_partition+0x314/0x5da block/partitions/check.c:167 rescan_partitions+0x19e/0x8c0 block/partition-generic.c:535 bdev_disk_changed+0x120/0x170 fs/block_dev.c:1435 __blkdev_get+0xc7d/0x11f0 fs/block_dev.c:1561 blkdev_get+0x271/0x8c0 fs/block_dev.c:1627 blkdev_open+0x19f/0x200 fs/block_dev.c:1788 do_dentry_open+0x3f1/0x1010 fs/open.c:796 vfs_open+0x9a/0xc0 fs/open.c:902 do_last fs/namei.c:3421 [inline] path_openat+0x905/0x2870 fs/namei.c:3537 do_filp_open+0x177/0x250 fs/namei.c:3567 do_sys_open+0x1dd/0x350 fs/open.c:1085 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fd445d3e840 Code: Bad RIP value. RSP: 002b:00007ffc5c7b9c88 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000564fdef1f980 RCX: 00007fd445d3e840 RDX: 0000564fde220fe3 RSI: 00000000000a0800 RDI: 0000564fdef20980 RBP: 00007ffc5c7b9e00 R08: 0000564fde220670 R09: 0000000000000010 R10: 0000564fde220d0c R11: 0000000000000246 R12: 00007ffc5c7b9d50 R13: 0000564fdef1d4b0 R14: 0000000000000003 R15: 000000000000000e INFO: task syz-executor.1:8289 blocked for more than 140 seconds. Not tainted 4.19.157-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28232 8289 6657 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 blkdev_put+0x25/0x480 fs/block_dev.c:1839 blkdev_close+0x88/0xd0 fs/block_dev.c:1888 __fput+0x249/0x7f0 fs/file_table.c:278 ____fput+0x9/0x10 fs/file_table.c:309 task_work_run+0x108/0x180 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x185/0x1e0 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4177b1 Code: 81 2f 00 48 89 04 24 48 c7 44 24 08 30 00 00 00 e8 74 ad 01 00 48 8d 05 07 bd 2a 00 48 89 04 24 48 c7 44 24 08 16 00 00 00 e8 <5b> ad 01 00 90 e8 15 87 04 00 e9 30 ff ff ff 64 48 8b 0c 25 f8 ff RSP: 002b:00007ffcff5dbda0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00000000004177b1 RDX: 0000001b2bc20000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 00007ffcff5dbe80 R11: 0000000000000293 R12: 000000000118c9a0 R13: 000000000118c9a0 R14: 00000000000003e8 R15: 000000000118c07c INFO: task syz-executor.1:8294 blocked for more than 140 seconds. Not tainted 4.19.157-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28776 8294 6657 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 __blkdev_get+0x19a/0x11f0 fs/block_dev.c:1478 blkdev_get+0x271/0x8c0 fs/block_dev.c:1627 blkdev_open+0x19f/0x200 fs/block_dev.c:1788 do_dentry_open+0x3f1/0x1010 fs/open.c:796 vfs_open+0x9a/0xc0 fs/open.c:902 do_last fs/namei.c:3421 [inline] path_openat+0x905/0x2870 fs/namei.c:3537 do_filp_open+0x177/0x250 fs/namei.c:3567 do_sys_open+0x1dd/0x350 fs/open.c:1085 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x417951 Code: 76 38 4c 8d 04 ca 4d 8d 40 20 83 3d b8 ce 1c 01 00 0f 85 85 00 00 00 4c 8b 4c 24 38 4c 89 4c ca 18 4c 8b 4c 24 40 4c 89 4c ca <28> 83 3d 97 ce 1c 01 00 75 3f 48 8b 44 24 48 48 89 44 ca 30 48 8b RSP: 002b:00007f85ea964820 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000417951 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f85ea964850 RBP: 000000000118c008 R08: 000000000000000f R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 000000000118bfd4 R13: 00007ffcff5dbd2f R14: 00007f85ea9659c0 R15: 000000000118bfd4 Showing all locks held in the system: 2 locks held by kworker/u4:3/114: 1 lock held by khungtaskd/1096: #0: 00000000101e443f (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4442 1 lock held by in:imklog/6155: 1 lock held by systemd-udevd/8217: #0: 000000007bd481c1 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x19a/0x11f0 fs/block_dev.c:1478 1 lock held by syz-executor.1/8289: #0: 000000007bd481c1 (&bdev->bd_mutex){+.+.}, at: blkdev_put+0x25/0x480 fs/block_dev.c:1839 1 lock held by syz-executor.1/8294: #0: 000000007bd481c1 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x19a/0x11f0 fs/block_dev.c:1478 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1096 Comm: khungtaskd Not tainted 4.19.157-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+0x17c/0x22a lib/dump_stack.c:118 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf5/0x119 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:203 [inline] watchdog+0x5c3/0xb40 kernel/hung_task.c:287 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 4.19.157-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: phy10 ieee80211_iface_work RIP: 0010:__lock_acquire+0x291/0x47c0 kernel/locking/lockdep.c:3321 Code: 08 48 85 db 0f 84 1d ff ff ff 48 8d bb 38 01 00 00 be 04 00 00 00 44 89 84 24 80 00 00 00 e8 d6 88 46 00 f0 ff 83 38 01 00 00 <49> 8d 86 80 08 00 00 44 8b 84 24 80 00 00 00 48 89 c2 48 89 44 24 RSP: 0018:ffff8880b5e0f3c0 EFLAGS: 00000012 RAX: fffffbfff13e029a RBX: ffffffff89f01390 RCX: ffffffff814b7dfa RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff89f014c8 RBP: ffff8880b5e0f5a8 R08: fffffbfff13e029a R09: fffffbfff13e0299 R10: fffffbfff13e0299 R11: ffffffff89f014cb R12: 0000000000000000 R13: ffffffff8878b9a0 R14: ffff8880b5dfc1c0 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbd169b9000 CR3: 00000000a39b2000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x180/0x3a0 kernel/locking/lockdep.c:3907 rcu_lock_acquire include/linux/rcupdate.h:242 [inline] rcu_read_lock include/linux/rcupdate.h:627 [inline] ieee80211_bss_info_update+0x209/0x16b0 net/mac80211/scan.c:92 ieee80211_rx_bss_info net/mac80211/ibss.c:1125 [inline] ieee80211_rx_mgmt_probe_beacon+0x71b/0x1480 net/mac80211/ibss.c:1607 ieee80211_ibss_rx_queued_mgmt+0x1d4/0x1690 net/mac80211/ibss.c:1634 ieee80211_iface_work+0x4bc/0x6e0 net/mac80211/iface.c:1345 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2155 worker_thread+0x85/0xb60 kernel/workqueue.c:2298 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415