Re: panic: mtx_lock_spin: recursed on non-recursive mutex vtbuf @ ..

Hey guys!

Yeah, it seems my.
I will look into it today.

Thanks!

пт, 22 трав. 2026 р. о 18:35 Ryan Libby <rlibby@freebsd.org> пише:

> On Fri, May 22, 2026 at 1:46 AM Bjoern A. Zeeb
> <bzeeb-lists@lists.zabbadoz.net> wrote:
> >
> > Hi,
> >
> > I was using the mouse in tmux on v1 when everying stopped.
> > Sadly we didn't switch to v0 for console but it seems I managed to get a
> dump only checking now; the kernel from then is already gone.
> >
> > core.txt said.
> >
> > panic: mtx_lock_spin: recursed on non-recursive mutex vtbuf @
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/dev/vt/vt_buf.c:744
> >
> > cpuid = 1
> > time = 1779437567
> > KDB: stack backtrace:
> > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
> 0xfffffe00d773e7a0
> > vpanic() at vpanic+0x149/frame 0xfffffe00d773e8d0
> > panic() at panic+0x43/frame 0xfffffe00d773e930
> > __mtx_lock_spin_flags() at __mtx_lock_spin_flags+0x11b/frame
> 0xfffffe00d773e970
> > vtbuf_flush_mark() at vtbuf_flush_mark+0x82/frame 0xfffffe00d773e9b0
> > vtbuf_unmark_on_cross() at vtbuf_unmark_on_cross+0xcc/frame
> 0xfffffe00d773e9d0
> > vtterm_fill() at vtterm_fill+0x27/frame 0xfffffe00d773ea00
> > teken_subr_erase_line() at teken_subr_erase_line+0x90/frame
> 0xfffffe00d773ea20
> > teken_state_2() at teken_state_2+0x497/frame 0xfffffe00d773ea40
> > teken_input_char() at teken_input_char+0x47/frame 0xfffffe00d773ea60
> > teken_input() at teken_input+0x9f/frame 0xfffffe00d773ea90
> > termtty_outwakeup() at termtty_outwakeup+0xcf/frame 0xfffffe00d773eb60
> > ttydisc_write() at ttydisc_write+0x337/frame 0xfffffe00d773ecd0
> > ttydev_write() at ttydev_write+0x13f/frame 0xfffffe00d773ed10
> > devfs_write_f() at devfs_write_f+0xf3/frame 0xfffffe00d773ed70
> > dofilewrite() at dofilewrite+0x81/frame 0xfffffe00d773edc0
> > sys_writev() at sys_writev+0x69/frame 0xfffffe00d773ee00
> > amd64_syscall() at amd64_syscall+0x168/frame 0xfffffe00d773ef30
> > fast_syscall_common() at fast_syscall_common+0xf8/frame
> 0xfffffe00d773ef30
> > --- syscall (121, FreeBSD ELF64, writev), rip = 0x82601d5aa, rsp =
> 0x8207a3408, rbp = 0x8207a3430 ---
> > KDB: enter: panic
> >
> >
> > In case it helps, I believe this is file:line as reported by gdb in
> core.txt:
> >
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/kern/kern_mutex.c:353
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/dev/vt/vt_buf.c:744
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/dev/vt/vt_buf.c:864
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/dev/vt/vt_buf.c:210
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/dev/vt/vt_buf.c:232
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/dev/vt/vt_core.c:1201
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/teken/teken.c:121
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/teken/teken_subr.h:558
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/teken/teken.c:255
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/teken/teken.c:284
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/teken/teken.c:317
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/kern/subr_terminal.c:422
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/sys/ttydevsw.h:114
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/kern/tty_ttydisc.c:658
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/kern/tty.c:550
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/fs/devfs/devfs_vnops.c:1980
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/sys/file.h:372
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/kern/sys_generic.c:565
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/kern/sys_generic.c:492
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/kern/sys_generic.c:478
> >      at
> /usr/home/test/Sources/git/FreeBSD/freebsd-src.git/sys/amd64/amd64/../../kern/subr_syscall.c:193
> >
> >
> > --
> > Bjoern A. Zeeb                                                     r15:7
> >
>
> I think it's probably related to or a regression from
> 8db0553ed6d8 ("vt: Clear cut-paste selection if the area intersects
> with the filled region")
>
> https://cgit.freebsd.org/src/commit/?id=8db0553ed6d8636d82a26896237099526b93be19
>
> which added vtbuf_unmark_on_cross() which is in your panic stack.
>
> I don't know this code but it looks like the mutex is first taken by
> teken_input / teken_funcs_pre_input / vtterm_pre_input and then again
> by teken_input with your panic stack.
>
> Ryan
>