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[[!tag open_issue_glibc]]

This started appearing when Jérémie's [[glibc]] signal patches were integrated:
very sporadically, but still now and then, `fork` will hang, as follows, and
typically in `/bin/sh`.

From a `libtool` invocation:

    #0  0x0107b13c in swtch_pri () at /build/eglibc-Q9jlik/eglibc-2.13/build-tree/hurd-i386-libc/mach/swtch_pri.S:2
    No locals.
    #1  0x0107c9c4 in __spin_lock_solid (lock=0x125080c) at spin-solid.c:27
    No locals.
    #2  0x01091427 in __spin_lock (__lock=<optimized out>) at ../mach/lock-intern.h:55
    No locals.
    #3  _hurd_sigstate_lock (ss=0x1250008) at hurdsig.c:172
    No locals.
    #4  0x011261ec in _hurd_critical_section_unlock (our_lock=<optimized out>) at ../hurd/hurd/signal.h:235
    No locals.
    #5  __fork () at ../sysdeps/mach/hurd/fork.c:706
            env = {{__jmpbuf = {18784244, 19197896, 1, 16925832, 16925460, 17980399}, __mask_was_saved = 0, __saved_mask = 33}}
            pid = 0
            err = <optimized out>
            __PRETTY_FUNCTION__ = "__fork"
            ss = 0x1250008
            threads = 0x0
            nthreads = 0
            stopped = 1
            i = 6
    [...]


Another one in `dash`:

    #0  0x0105927c in swtch_pri () at /media/erich/home/thomas/tmp/glibc/debian/eglibc-2.13/build-tree/hurd-i386-libc/mach/swtch_pri.S:2
    No locals.
    #1  0x0105ac44 in __spin_lock_solid (lock=0x123580c) at spin-solid.c:27
    No locals.
    #2  0x010701c7 in __spin_lock (__lock=<optimized out>) at ../mach/lock-intern.h:55
    No locals.
    #3  _hurd_sigstate_lock (ss=0x1235008) at hurdsig.c:172
    No locals.
    #4  0x011048f0 in _hurd_critical_section_unlock (our_lock=0x1235008) at ../hurd/hurd/signal.h:235
            ss = 0x1235008
            pending = <optimized out>
    #5  __fork () at ../sysdeps/mach/hurd/fork.c:706
            env = {{__jmpbuf = {18780148, 19087304, 134621988, 0, 16938700, 17842902}, __mask_was_saved = 0, __saved_mask = 4294967295}}
            pid = 0
            err = 0
            __PRETTY_FUNCTION__ = "__fork"
            ss = 0x1235008
            threads = 0x0
            nthreads = 0
            stopped = 1
            i = 6
    [...]