Matthew Bloch wrote:
Hi there, We are running lots of kvm processes in screen and found that about 1 in 5 froze shortly after startup startup with a backtrace like this one: #0 0xf7c7fcd9 in pthread_exit () from /lib/tls/libc.so.6 #1 0xf7cfbe62 in wresize () from /lib/libncurses.so.5 #2 0xf7cfb7ab in is_term_resized () from /lib/libncurses.so.5 #3 0xf7cfb877 in is_term_resized () from /lib/libncurses.so.5 #4 0xf7cfba31 in resize_term () from /lib/libncurses.so.5 #5 0x080d3dd9 in vga_init () #6 <signal handler called> #7 0xf7c0da5b in free () from /lib/tls/libc.so.6 #8 0xf7c0effe in calloc () from /lib/tls/libc.so.6 #9 0xf7cf222e in newpad () from /lib/libncurses.so.5 #10 0x080d3549 in vga_init () We're just using the lenny version of kvm from 2008-12-16. On casual inspection, the SIGWINCH signal handling looked ropey to me - grandpa always told me not to do any real work in a signal handler, and the backtrace suggested re-entrancy problems in curses, so I changed the behaviour to set a flag and do the work in the main loop instead. Maybe I'm reading the backtrace wrong. So far that means that when you resize the window, the display is corrupt until the VM outputs some text, or the user hits a key. But I think it has solved the freezing / crashing bug too - would appreciate any comments on my analysis or proposed solution.
It's racy with select(). A better fix would be to create a pipe and write to that pipe in the SIGWINCH handler. You should then register an io callback using qemu_set_fd_handler2() that does the actions for SIGWINCH.
Regards, Anthony Liguori -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
