Created attachment 1096765 [details] reproducer In attachment is reproduce. This should affect all fedora releases. In rawhide reproducer succeeds in 1st thread and then SEGFAULTs. In f23 reproducer "succeeds", but incorrect data/usernames are outputted ("(null)"instead of "root"). I'm already in touch with codonell/fweimer, opening this bug to track this issue in Fedora.
The problem here is that the copy of libc.so.6 loaded later does not know of the threading state of the entire process. In a sense, it is like creating a thread with clone(2) and then calling into glibc (although the static/dlmopen case works better because a thread descriptor has been set up). Or TSRs in the good-old DOS days. This will be quite difficult to fix, particularly documenting the aspects that cannot be realistically fixed.
This bug appears to have been reported against 'rawhide' during the Fedora 24 development cycle. Changing version to '24'. More information and reason for this action is here: https://fedoraproject.org/wiki/Fedora_Program_Management/HouseKeeping/Fedora24#Rawhide_Rebase
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This is equivalent to solving the static vs dynamic namespace issues, and similarly fixing dlmopen. We aren't going to fix this any time soon. So for F24 I'm going to mark this CLOSED/DUPLICATE of *** This bug has been marked as a duplicate of bug 1475501 ***