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Re: [Xen-devel] [PATCH 1/3] libxl: Fix libxl_postfork_child_noexec deadlock etc.

On Mon, 24 Feb 2014, Ian Campbell wrote:

On Mon, 2014-02-24 at 14:19 +0000, Ian Jackson wrote:
libxl_postfork_child_noexec would nestedly reaquire the non-recursive
"no_forking" mutex: atfork_lock uses it, as does sigchld_user_remove.
The result on Linux is that the process always deadlocks before
returning from this function.

This is used by xl's console child.  So, the ultimate effect is that
xl with pygrub does not manage to connect to the pygrub console.
This beahviour was reported by Michael Young in Xen 4.4.0 RC5.


Michael reported this earlier on -rc2 as well but it fell through the
cracks because I failed to properly appreciate the severity. Sorry.

No that was a different problem (you get some warnings and a messed up terminal sesssion on dom0 after using pygrub). This is a new problem, probably introduced in rc4 (which I didn't get around to testing).

        Michael Young

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