Bug 202745
| Summary: | pktcdvd triggers a lock inversion complaint | ||
|---|---|---|---|
| Product: | IO/Storage | Reporter: | Bart Van Assche (bvanassche) |
| Component: | Block Layer | Assignee: | Jens Axboe (axboe) |
| Status: | NEW --- | ||
| Severity: | normal | ||
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | v5.1-rc1 (next-20190301) | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
This is what appears during boot in the kernel log since at least kernel v4.8: pktcdvd: pktcdvd0: writer mapped to sr0 ============================================ WARNING: possible recursive locking detected 5.0.0-rc8-next-20190301-dbg+ #1 Not tainted -------------------------------------------- systemd-udevd/3737 is trying to acquire lock: 0000000091432535 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x10e/0xa00 but task is already holding lock: 00000000fb0b5b8d (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x10e/0xa00 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&bdev->bd_mutex); lock(&bdev->bd_mutex); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by systemd-udevd/3737: #0: 00000000fb0b5b8d (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x10e/0xa00 #1: 00000000656f5dab (pktcdvd_mutex){+.+.}, at: pkt_open+0x9e/0x880 [pktcdvd] #2: 00000000a24adc46 (&ctl_mutex#2){+.+.}, at: pkt_open+0xac/0x880 [pktcdvd] stack backtrace: CPU: 1 PID: 3737 Comm: systemd-udevd Not tainted 5.0.0-rc8-next-20190301-dbg+ #1 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x86/0xca __lock_acquire.cold.66+0x10d/0x2b8 lock_acquire+0xe3/0x200 __mutex_lock+0x106/0xc00 mutex_lock_nested+0x1b/0x20 __blkdev_get+0x10e/0xa00 blkdev_get+0x371/0x5c0 pkt_open+0x213/0x880 [pktcdvd] __blkdev_get+0x236/0xa00 blkdev_get+0x1fa/0x5c0 blkdev_open+0xe9/0x100 do_dentry_open+0x29a/0x6b0 vfs_open+0x58/0x60 path_openat+0x723/0x1a30 do_filp_open+0x121/0x1b0 do_sys_open+0x1e2/0x2d0 __x64_sys_openat+0x59/0x70 do_syscall_64+0x77/0x220 entry_SYSCALL_64_after_hwframe+0x49/0xbe