bisecting fixing commit since 7472c4028e2357202949f99ad94c5a5a34f95666 building syzkaller on fd2a5f28eb5e2b7c83b5e814f53e44e2a5dde24c testing commit 7472c4028e2357202949f99ad94c5a5a34f95666 with gcc (GCC) 8.1.0 kernel signature: 658925bde9d0385c6b0a4bff8e68087eaa35212a56a325b149bf94aa871713f7 run #0: crashed: possible deadlock in seq_read run #1: crashed: possible deadlock in seq_read run #2: crashed: possible deadlock in lock_trace run #3: crashed: possible deadlock in seq_read run #4: crashed: possible deadlock in lock_trace run #5: crashed: possible deadlock in lock_trace run #6: crashed: possible deadlock in lock_trace run #7: crashed: possible deadlock in lock_trace run #8: crashed: possible deadlock in seq_read run #9: crashed: possible deadlock in seq_read testing current HEAD 17a87580a8856170d59aab302226811a4ae69149 testing commit 17a87580a8856170d59aab302226811a4ae69149 with gcc (GCC) 8.1.0 kernel signature: cbf653aff07a8df5ddb4be889415234b912138cd9c2dd831c225e03a78a1dda9 run #0: crashed: possible deadlock in lock_trace run #1: crashed: possible deadlock in lock_trace run #2: crashed: possible deadlock in seq_read run #3: crashed: possible deadlock in lock_trace run #4: crashed: possible deadlock in lock_trace run #5: crashed: possible deadlock in lock_trace run #6: crashed: possible deadlock in lock_trace run #7: crashed: possible deadlock in lock_trace run #8: crashed: possible deadlock in lock_trace run #9: crashed: possible deadlock in lock_trace revisions tested: 2, total time: 28m50.979703361s (build: 20m0.526201384s, test: 7m26.996439605s) the crash still happens on HEAD commit msg: Linux 4.19.133 crash: possible deadlock in lock_trace overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory ====================================================== WARNING: possible circular locking dependency detected 4.19.133-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.2/14638 is trying to acquire lock: 0000000010745882 (&sig->cred_guard_mutex){+.+.}, at: lock_trace+0x3f/0xb0 fs/proc/base.c:402 but task is already holding lock: 0000000098390e08 (&p->lock){+.+.}, at: seq_read+0x66/0x1000 fs/seq_file.c:161 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: overlayfs: './file0' not a directory -> #3 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf5/0x1210 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 seq_read+0x66/0x1000 fs/seq_file.c:161 do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x362/0x560 fs/read_write.c:925 vfs_readv+0xc9/0x130 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x411/0x900 fs/splice.c:417 do_splice_to+0xe3/0x120 fs/splice.c:881 splice_direct_to_actor+0x296/0x870 fs/splice.c:959 do_splice_direct+0x14c/0x270 fs/splice.c:1068 do_sendfile+0x481/0xd00 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x198/0x1e0 fs/read_write.c:1494 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 overlayfs: './file0' not a directory entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (sb_writers#3){.+.+}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x17d/0x2a0 fs/super.c:1387 file_start_write include/linux/fs.h:2776 [inline] ovl_write_iter+0x80f/0xb10 fs/overlayfs/file.c:280 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 __kernel_write+0xe4/0x350 fs/read_write.c:506 write_pipe_buf+0x154/0x1f0 fs/splice.c:798 splice_from_pipe_feed fs/splice.c:503 [inline] __splice_from_pipe+0x2cb/0x720 fs/splice.c:627 splice_from_pipe+0xbb/0x120 fs/splice.c:662 default_file_splice_write+0x18/0x50 fs/splice.c:810 do_splice_from fs/splice.c:852 [inline] direct_splice_actor+0x104/0x1c0 fs/splice.c:1025 overlayfs: './file0' not a directory splice_direct_to_actor+0x304/0x870 fs/splice.c:980 overlayfs: './file0' not a directory do_splice_direct+0x14c/0x270 fs/splice.c:1068 do_sendfile+0x481/0xd00 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x198/0x1e0 fs/read_write.c:1494 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_key[depth]){+.+.}: down_write+0x38/0x90 kernel/locking/rwsem.c:70 inode_lock include/linux/fs.h:748 [inline] process_measurement+0x69e/0x14b0 security/integrity/ima/ima_main.c:205 ima_file_check+0xc8/0x110 security/integrity/ima/ima_main.c:391 do_last fs/namei.c:3425 [inline] path_openat+0x746/0x3c60 fs/namei.c:3537 do_filp_open+0x177/0x250 fs/namei.c:3567 do_open_execat+0xe1/0x4b0 fs/exec.c:853 __do_execve_file.isra.32+0x113a/0x1d40 fs/exec.c:1757 do_execveat_common fs/exec.c:1866 [inline] do_execve fs/exec.c:1883 [inline] __do_sys_execve fs/exec.c:1964 [inline] __se_sys_execve fs/exec.c:1959 [inline] __x64_sys_execve+0x8a/0xb0 fs/exec.c:1959 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sig->cred_guard_mutex){+.+.}: lock_acquire+0x173/0x3d0 kernel/locking/lockdep.c:3907 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf5/0x1210 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 lock_trace+0x3f/0xb0 fs/proc/base.c:402 proc_pid_personality+0x17/0xb0 fs/proc/base.c:2926 proc_single_show+0xf3/0x170 fs/proc/base.c:755 seq_read+0x3e2/0x1000 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x362/0x560 fs/read_write.c:925 vfs_readv+0xc9/0x130 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x411/0x900 fs/splice.c:417 do_splice_to+0xe3/0x120 fs/splice.c:881 splice_direct_to_actor+0x296/0x870 fs/splice.c:959 do_splice_direct+0x14c/0x270 fs/splice.c:1068 do_sendfile+0x481/0xd00 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x198/0x1e0 fs/read_write.c:1494 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> sb_writers#3 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(sb_writers#3); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 2 locks held by syz-executor.2/14638: #0: 000000002c7bce94 (sb_writers#16){.+.+}, at: file_start_write include/linux/fs.h:2776 [inline] #0: 000000002c7bce94 (sb_writers#16){.+.+}, at: do_sendfile+0x81e/0xd00 fs/read_write.c:1446 #1: 0000000098390e08 (&p->lock){+.+.}, at: seq_read+0x66/0x1000 fs/seq_file.c:161 stack backtrace: CPU: 1 PID: 14638 Comm: syz-executor.2 Not tainted 4.19.133-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 print_circular_bug.isra.34.cold.55+0x1bd/0x27d kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1865 [inline] check_prevs_add kernel/locking/lockdep.c:1978 [inline] validate_chain kernel/locking/lockdep.c:2419 [inline] __lock_acquire+0x30df/0x4980 kernel/locking/lockdep.c:3415 lock_acquire+0x173/0x3d0 kernel/locking/lockdep.c:3907 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf5/0x1210 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 lock_trace+0x3f/0xb0 fs/proc/base.c:402 proc_pid_personality+0x17/0xb0 fs/proc/base.c:2926 proc_single_show+0xf3/0x170 fs/proc/base.c:755 seq_read+0x3e2/0x1000 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x362/0x560 fs/read_write.c:925 vfs_readv+0xc9/0x130 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x411/0x900 fs/splice.c:417 do_splice_to+0xe3/0x120 fs/splice.c:881 splice_direct_to_actor+0x296/0x870 fs/splice.c:959 do_splice_direct+0x14c/0x270 fs/splice.c:1068 do_sendfile+0x481/0xd00 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x198/0x1e0 fs/read_write.c:1494 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c529 Code: 2d 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 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff0ceaafc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007ff0ceab06d4 RCX: 000000000045c529 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000283 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008d1 R14: 00000000004cb430 R15: 000000000076bf2c overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a directory overlayfs: './file0' not a 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