Created attachment 522617 [details] test case demonstrating the issue There appears to be a strange bug in glibc that causes deadlocks when calling fork() from threads. We had a testcase in GLib failing from time to time because of this. I've attached a minimal testcase that uses only pure pthreads + libc. Compile it with -pthread and run it. It should fill your screen with dots for a while, then hang when it hits the bug (which happens randomly anywhere between 1 dot and hundreds). I've already received independent verification that this testcase hangs on several people's computers. I believe this to be an upstream issue since this bug is visible on Ubuntu as well, but the glibc website says I should file bugs against distributions first. I also believe the issue to be a regression since older Fedora and RHEL releases are unaffected. The problem appears to affect both 32 and 64bits. Description of problem: Some notes: - compiling the testcase with -static has the side-effect of causing the bug to go away - compiling the testcase with -DFORK_DIRECTLY also appears to solve the problem - replacing the execv() with a direct exit(0) doesn't solve the problem but causes the frequency to change The fact that both static linking and making the fork() syscall directly cause the problem to disappear leads me to believe that this is a libc bug rather than a kernel bug (which is the only other possibility). I'm not 100% sure of that, though, since libc actually uses the clone() syscall to implement fork(), so there could be a different inside the kernel because of that.
glibc-2.14.90-9 has been submitted as an update for Fedora 16. https://admin.fedoraproject.org/updates/glibc-2.14.90-9
Thanks for the awesome turnaround. I installed the update from testing on my F16 system and it appears to fix the problem.
Package glibc-2.14.90-9: * should fix your issue, * was pushed to the Fedora 16 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing glibc-2.14.90-9' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/glibc-2.14.90-9 then log in and leave karma (feedback).
Package glibc-2.14.90-10: * should fix your issue, * was pushed to the Fedora 16 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing glibc-2.14.90-10' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/glibc-2.14.90-10 then log in and leave karma (feedback).
glibc-2.14.90-10 has been pushed to the Fedora 16 stable repository. If problems still persist, please make note of it in this bug report.