bisecting fixing commit since 765675379b6253b6901563e649a2f87d28ada3ff building syzkaller on 143a10e9d6320fa7e38693bd8df375fcf4446ae6 testing commit 765675379b6253b6901563e649a2f87d28ada3ff with gcc (GCC) 8.1.0 kernel signature: 62f089741f3e5b8bcb220774bcac9d0ace23341f887b21f1aea599ca16cbe3ff run #0: crashed: INFO: task hung in d_alloc_parallel run #1: crashed: INFO: task hung in d_alloc_parallel run #2: OK run #3: crashed: INFO: task hung in d_alloc_parallel run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK testing current HEAD 10ad6cfd57360760116cde00a8ef756e121367a9 testing commit 10ad6cfd57360760116cde00a8ef756e121367a9 with gcc (GCC) 8.1.0 kernel signature: 8ee9501f5d48afd29cee5909efc53110d1472f994cc7bbfc55e2fb27b135bb39 run #0: crashed: INFO: task hung in d_alloc_parallel run #1: crashed: INFO: task hung in d_alloc_parallel run #2: crashed: INFO: task hung in d_alloc_parallel run #3: crashed: INFO: task hung in d_alloc_parallel run #4: crashed: INFO: task hung in d_alloc_parallel run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK revisions tested: 2, total time: 39m19.033327103s (build: 19m10.783389665s, test: 19m16.34627125s) the crash still happens on HEAD commit msg: Linux 4.19.148 crash: INFO: task hung in d_alloc_parallel INFO: task syz-executor.1:12661 blocked for more than 140 seconds. Not tainted 4.19.148-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28664 12661 6559 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 d_wait_lookup fs/dcache.c:2428 [inline] d_alloc_parallel+0xdc6/0x1750 fs/dcache.c:2510 lookup_open+0x46e/0x1d30 fs/namei.c:3148 do_last fs/namei.c:3327 [inline] path_openat+0x1683/0x3c60 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: 0033:0x45c8a9 Code: 8d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fde67b3cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00000000004f6880 RCX: 000000000045c8a9 RDX: 0000000000000049 RSI: 00000000000a8482 RDI: 0000000020000000 RBP: 000000000078c040 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000773 R14: 00000000005251df R15: 00007fde67b3d6d4 Showing all locks held in the system: 1 lock held by khungtaskd/1080: #0: 0000000003f1751b (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4442 2 locks held by syz-executor.1/12632: #0: 00000000055aa5bc (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 00000000055aa5bc (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 00000000055aa5bc (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 #1: 00000000745d578b (&fi->mutex){+.+.}, at: fuse_lock_inode+0x9a/0xc0 fs/fuse/inode.c:365 2 locks held by syz-executor.1/12661: #0: 00000000884ead95 (sb_writers#16){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline] #0: 00000000884ead95 (sb_writers#16){.+.+}, at: mnt_want_write+0x3c/0xa0 fs/namespace.c:360 #1: 00000000055aa5bc (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #1: 00000000055aa5bc (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #1: 00000000055aa5bc (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 1 lock held by syz-executor.3/18429: #0: 00000000579c28da (&type->i_mutex_dir_key#8){++++}, at: inode_lock include/linux/fs.h:748 [inline] #0: 00000000579c28da (&type->i_mutex_dir_key#8){++++}, at: lock_mount+0x82/0x290 fs/namespace.c:2039 2 locks held by syz-executor.3/18430: #0: 0000000034e2ab59 (sb_writers#16){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline] #0: 0000000034e2ab59 (sb_writers#16){.+.+}, at: mnt_want_write+0x3c/0xa0 fs/namespace.c:360 #1: 00000000579c28da (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #1: 00000000579c28da (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #1: 00000000579c28da (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 2 locks held by syz-executor.3/18409: #0: 00000000579c28da (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 00000000579c28da (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 00000000579c28da (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 #1: 000000001b304f36 (&fi->mutex){+.+.}, at: fuse_lock_inode+0x9a/0xc0 fs/fuse/inode.c:365 1 lock held by syz-executor.2/18436: #0: 000000005a71071a (&type->i_mutex_dir_key#8){++++}, at: inode_lock include/linux/fs.h:748 [inline] #0: 000000005a71071a (&type->i_mutex_dir_key#8){++++}, at: lock_mount+0x82/0x290 fs/namespace.c:2039 1 lock held by syz-executor.2/18439: #0: 000000005a71071a (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 000000005a71071a (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 000000005a71071a (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 2 locks held by syz-executor.2/18427: #0: 000000005a71071a (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 000000005a71071a (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 000000005a71071a (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 #1: 00000000a343194d (&fi->mutex){+.+.}, at: fuse_lock_inode+0x9a/0xc0 fs/fuse/inode.c:365 1 lock held by syz-executor.0/18473: #0: 0000000094b340a8 (&type->i_mutex_dir_key#8){++++}, at: inode_lock include/linux/fs.h:748 [inline] #0: 0000000094b340a8 (&type->i_mutex_dir_key#8){++++}, at: lock_mount+0x82/0x290 fs/namespace.c:2039 1 lock held by syz-executor.0/18476: #0: 0000000094b340a8 (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 0000000094b340a8 (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 0000000094b340a8 (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 1 lock held by syz-executor.5/18480: #0: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: inode_lock include/linux/fs.h:748 [inline] #0: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: lock_mount+0x82/0x290 fs/namespace.c:2039 2 locks held by syz-executor.5/18481: #0: 00000000548ca874 (sb_writers#16){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline] #0: 00000000548ca874 (sb_writers#16){.+.+}, at: mnt_want_write+0x3c/0xa0 fs/namespace.c:360 #1: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #1: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #1: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 1 lock held by syz-executor.5/18486: #0: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 2 locks held by syz-executor.0/18457: #0: 0000000094b340a8 (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 0000000094b340a8 (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 0000000094b340a8 (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 #1: 00000000a9c8aeb2 (&fi->mutex){+.+.}, at: fuse_lock_inode+0x9a/0xc0 fs/fuse/inode.c:365 2 locks held by syz-executor.5/18462: #0: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 0000000098e145e0 (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 #1: 000000005283fdaf (&fi->mutex){+.+.}, at: fuse_lock_inode+0x9a/0xc0 fs/fuse/inode.c:365 1 lock held by syz-executor.1/18487: #0: 000000009a1f803c (&type->i_mutex_dir_key#8){++++}, at: inode_lock include/linux/fs.h:748 [inline] #0: 000000009a1f803c (&type->i_mutex_dir_key#8){++++}, at: lock_mount+0x82/0x290 fs/namespace.c:2039 1 lock held by syz-executor.1/18490: #0: 000000009a1f803c (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 000000009a1f803c (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 000000009a1f803c (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 2 locks held by syz-executor.1/18472: #0: 000000009a1f803c (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 000000009a1f803c (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 000000009a1f803c (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 #1: 00000000545482e8 (&fi->mutex){+.+.}, at: fuse_lock_inode+0x9a/0xc0 fs/fuse/inode.c:365 3 locks held by syz-executor.4/18499: #0: 0000000056ffefde (sb_writers#16){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline] #0: 0000000056ffefde (sb_writers#16){.+.+}, at: mnt_want_write+0x3c/0xa0 fs/namespace.c:360 #1: 0000000099420bf5 (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #1: 0000000099420bf5 (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #1: 0000000099420bf5 (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 #2: 00000000b547a6b8 (&fi->mutex){+.+.}, at: fuse_lock_inode+0x9a/0xc0 fs/fuse/inode.c:365 1 lock held by syz-executor.4/18503: #0: 0000000099420bf5 (&type->i_mutex_dir_key#8){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] #0: 0000000099420bf5 (&type->i_mutex_dir_key#8){++++}, at: do_last fs/namei.c:3326 [inline] #0: 0000000099420bf5 (&type->i_mutex_dir_key#8){++++}, at: path_openat+0x1667/0x3c60 fs/namei.c:3537 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1080 Comm: khungtaskd Not tainted 4.19.148-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+0x123/0x177 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.4+0x3e/0x76 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xe6/0x11a 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: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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 3694 Comm: systemd-journal Not tainted 4.19.148-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:lock_acquire+0x1fb/0x3d0 kernel/locking/lockdep.c:3911 Code: ea 03 80 3c 02 00 0f 85 aa 01 00 00 48 83 3d 23 70 06 07 00 0f 84 31 01 00 00 48 8b 7d c8 57 9d 0f 1f 44 00 00 48 8d 65 d8 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 65 8b 05 64 eb b5 7e 83 f8 3f 0f 87 RSP: 0018:ffff8880935cfa40 EFLAGS: 00000082 RAX: dffffc0000000000 RBX: ffff88812fffbc40 RCX: 1ffff110126b893d RDX: 1ffffffff10a40b9 RSI: 0000000000000000 RDI: 0000000000000082 RBP: ffff8880935cfa60 R08: 000000000000239f R09: 0000000000000000 R10: ffff8880935c49c8 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f8c040218c0(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8c01413000 CR3: 000000009364b000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152 rmqueue mm/page_alloc.c:3023 [inline] get_page_from_freelist+0x5af/0x3d00 mm/page_alloc.c:3372 __alloc_pages_nodemask+0x34d/0x710 mm/page_alloc.c:4398 __alloc_pages include/linux/gfp.h:496 [inline] __alloc_pages_node include/linux/gfp.h:509 [inline] kmem_getpages mm/slab.c:1412 [inline] cache_grow_begin+0x91/0x8d0 mm/slab.c:2682 cache_alloc_refill mm/slab.c:3049 [inline] ____cache_alloc mm/slab.c:3132 [inline] __do_cache_alloc mm/slab.c:3354 [inline] slab_alloc mm/slab.c:3389 [inline] kmem_cache_alloc+0x663/0x730 mm/slab.c:3557 getname_flags+0xb8/0x520 fs/namei.c:140 getname fs/namei.c:211 [inline] user_path_create fs/namei.c:3696 [inline] do_mkdirat+0x9a/0x220 fs/namei.c:3834 __do_sys_mkdir fs/namei.c:3858 [inline] __se_sys_mkdir fs/namei.c:3856 [inline] __x64_sys_mkdir+0x57/0x80 fs/namei.c:3856 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f8c032dd687 Code: 00 b8 ff ff ff ff c3 0f 1f 40 00 48 8b 05 09 d8 2b 00 64 c7 00 5f 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 b8 53 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 d7 2b 00 f7 d8 64 89 01 48 RSP: 002b:00007fff0bd23658 EFLAGS: 00000293 ORIG_RAX: 0000000000000053 RAX: ffffffffffffffda RBX: 00007fff0bd26570 RCX: 00007f8c032dd687 RDX: 00007f8c03d4ea00 RSI: 00000000000001ed RDI: 000055d2e4c758c0 RBP: 00007fff0bd23690 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000069 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fff0bd26570 R15: 00007fff0bd23b80