Red Hat Bugzilla – Bug 624135
emacs startup hangs with /dev/tty write
Last modified: 2011-06-28 10:36:32 EDT
Intermittently, starting emacs on a pty (ssh) hangs uninterruptibly.
This problem has existed as far back as Fedora-11.
% uname -a
Linux super.elastic.org 18.104.22.168-147.fc13.x86_64 #1 SMP Tue Jul 6 22:32:17 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux
% strace -p $PID
strace -p 10826
Process 10826 attached - interrupt to quit
write(3, "\33[32;74H\33[?25ldone\33[H\n\33[?25h", 28^C <unfinished ...>
Process 10826 detached
% lsof -p $PID
emacs 10826 fche 0u CHR 136,0 0t0 3 /dev/pts/0
emacs 10826 fche 1u CHR 136,0 0t0 3 /dev/pts/0
emacs 10826 fche 2u CHR 136,0 0t0 3 /dev/pts/0
emacs 10826 fche 3u CHR 5,0 0t0 5494 /dev/tty
% kill -9 $PID
... does nothing ...
% sysrq-t sez:
Aug 13 14:48:22 super kernel: emacs S 0000000000000000 0 10826 10825 0x00000080
Aug 13 14:48:22 super kernel: ffff8802c185ddf8 0000000000000082 0000000000000000 ffff8802c185dd58
Aug 13 14:48:22 super kernel: ffffffff810fe0e3 0000000000000001 ffff8802c185dd78 ffff8802c185dfd8
Aug 13 14:48:22 super kernel: ffff8802c185dfd8 000000000000f9b0 00000000000157c0 ffff88043c0b03c8
Aug 13 14:48:22 super kernel: Call Trace:
Aug 13 14:48:22 super kernel: [<ffffffff810fe0e3>] ? lookup_page_cgroup+0x2d/0x43
Aug 13 14:48:22 super kernel: [<ffffffff812810ff>] n_tty_write+0x2d5/0x34c
Aug 13 14:48:22 super kernel: [<ffffffff81045f1e>] ? default_wake_function+0x0/0xf
Aug 13 14:48:22 super kernel: [<ffffffff8127fd9f>] tty_write+0x198/0x240
Aug 13 14:48:22 super kernel: [<ffffffff81280e2a>] ? n_tty_write+0x0/0x34c
Aug 13 14:48:22 super kernel: [<ffffffff8110155f>] vfs_write+0xa9/0x106
Aug 13 14:48:22 super kernel: [<ffffffff81101672>] sys_write+0x45/0x69
Aug 13 14:48:22 super kernel: [<ffffffff81009b02>] system_call_fastpath+0x16/0x1b
In case it's relevant, glibc's $MALLOC_CHECK_=1 on this machine.
This just occurred to me so I haven't tested without that.
A gdb stack trace from the dead emacs process:
0x0000003b2f6d41e0 in __write_nocancel () at ../sysdeps/unix/syscall-template.S:82
82 T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
Missing separate debuginfos, use: debuginfo-install emacs-23.2-1.fc13.x86_64
#0 0x0000003b2f6d41e0 in __write_nocancel () at ../sysdeps/unix/syscall-template.S:82
#1 0x0000003b2f671303 in _IO_new_file_write (f=0xec8cd0, data=<value optimized out>, n=28)
#2 0x0000003b2f6728b5 in new_do_write (fp=0xec8cd0, data=
0xb0c4c0 "\033[32;74H\033[?25ldone\033[H\n\033[?25he/emacs/site-lisp/site-start.d/focus-init.el (source)...\033[K\033[H\n\033[?25hFundamental)", '-' <repeats 53 times>, "\033[0m\033[39;49m\033[m\r\n\033[A\033[H\033[?25h", to_do=28) at fileops.c:522
#3 _IO_new_do_write (fp=0xec8cd0, data=
0xb0c4c0 "\033[32;74H\033[?25ldone\033[H\n\033[?25he/emacs/site-lisp/site-start.d/focus-init.el (source)...\033[K\033[H\n\033[?25hFundamental)", '-' <repeats 53 times>, "\033[0m\033[39;49m\033[m\r\n\033[A\033[H\033[?25h", to_do=28) at fileops.c:495
#4 0x0000003b2f671ab8 in _IO_new_file_sync (fp=0xec8cd0) at fileops.c:897
#5 0x0000003b2f66630a in _IO_fflush (fp=0xec8cd0) at iofflush.c:43
#6 0x000000000041c8f7 in ?? ()
#7 0x000000000044f95e in ?? ()
Sorry, I didn't have debuginfo for the emacs process, and a tty hangup
(ssh disconnection) did appear to kill it. Weird.
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