Created attachment 124531 [details] This is a small program that triggers the fault. It requires root privilege to run. Before kernel 3.12.1 one could mmap() the RX and TX ring buffers for a network socket and reliably release them with munmap(). Starting with kernel 3.12.1 and running through the latest kernel I tested (3.1.14) this no longer works. The call to munmap() never returns. Parts of the system may continue to operate, but the system can not be shut down by normal means. It takes a hardware reset or power cycle to recover. I've got a short program, extracted from something we've been running for several years, that triggers the problem. I believe that every kernel from 3.12.1 and forward faults when this is run. This has been reported to the Fedora crew, and it was suggested that I kick this upstream. So here I am.
Probably best posted to netdev@vger.kernel.org so it gets some prompt action
Patch has been posted by me to Andrew Morton and sits in his tree waiting to be picked up by Linus and stable trees: http://ozlabs.org/~akpm/mmotm/broken-out/mm-include-vm_mixedmap-flag-in-the-vm_special-list-to-avoid-munlocking.patch Thanks.