Re: Signal 11 when using 'ps'

[Chris Gray <cgray@tribsoft.com>]

>>>>> Ed Cogburn writes:

    ec> 	Thanks guys for the help.

    ec> 	Ok first, my CPU is not overclocked.  My hardware is
    ec> all fairly new though, so I'll list the major components:


    ec> 	Athlon "Thunderbird" CPU, 1Ghz

You lucky bastard.

    ec> 	Fourth, the sig11 errors are occuring at the same
    ec> place every time.  100% consistent. (Although ps's output has
    ec> changed, see below.)

Good, that makes it look like a real bug.

    ec> 	Ok, I've been playing around with BIOS settings and
    ec> noticed something has changed, ps is now sending its output to
    ec> the screen twice.  ???  The following is a fragment of an
    ec> strace of ps, followed by a gdb session showing the duplicated
    ec> output and a backtrace, if that helps.

    ec> **************************************
    ec> open("/boot/System.map-2.2.17", O_RDONLY|O_NONBLOCK|O_NOCTTY) = -1
    ec> ENOENT (No such file or directory)
    ec> open("/boot/System.map", O_RDONLY|O_NONBLOCK|O_NOCTTY) = 6
    ec> fstat(6, {st_mode=S_IFREG|0664, st_size=141296, ...}) = 0
    ec> old_mmap(NULL, 141297, PROT_READ|PROT_WRITE, MAP_PRIVATE, 6, 0) =
    ec> 0x401df000
    ec> close(6)                                = 0
    ec> mremap(0x401be000, 135168, 12288, MREMAP_MAYMOVE) = 0x401be000
    ec> --- SIGSEGV (Segmentation fault) ---

This is exactly the same as last time.

    ec> Starting program: /bin/ps
    ec> (no debugging symbols found)...
    ec> (no debugging symbols found)...
    ec> (no debugging symbols found)...

This means that the output could be totally useless.  You need to
recompile with debugging symbols.

    ec> #0  0x40022d1f in tty_to_dev () from /lib/libproc.so.2.0.6
    ec> #1  0x4002300a in open_psdb () from /lib/libproc.so.2.0.6
    ec> #2  0x804fcbf in strcpy ()
    ec> #3  0x40047cfc in __libc_start_main () from /lib/libc.so.6
    ec> (gdb)
    ec> **************************************


    ec> 	This is an strace of console-apt which is also giving
    ec> me sig11 errors (same place, same time, 100% consistent):

Console-apt has bugs.  This is when you are resizing the window,
right?  It's probably been fixed in CVS for a long time now and just
not released.

    ec> 	What should I do?  Would compiling ps with debug info
    ec> and stepping through it help?  Should I try something else?

Please do compile ps with debugging symbols and send a gdb backtrace.
I'll have a look at the source and see if I can find the bug.  Also,
send a bug report to the maintainers of procps, both upstream and
Debian using the "bug" command.

-- 
Chris