Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.16 kernel[0].
If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'. If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'. Once testing of the upstream kernel is complete, please mark this bug as "Confirmed". Thanks in advance. [0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.16 ** Changed in: linux (Ubuntu) Importance: Undecided => Medium -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1761619 Title: eventfd / poll interaction bug Status in linux package in Ubuntu: Incomplete Bug description: In 17.10, I'm running into a new problem. This didn't happen to me on 16.04. I have some code that uses eventfds to signal things, and the code is not working -- after writing the eventfd, it does not come back readable from another thread using poll(). Here's a snippet from strace: ``` eventfd2(0, 0) = 5 fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 1), ...}) = 0 write(1, "OPEN FD 5\n", 10OPEN FD 5 ) = 10 write(5, "\1\0\0\0\0\0\0\0", 8) = 8 nanosleep({tv_sec=0, tv_nsec=100000000}, 0x7fffd0cea1a0) = 0 poll([{fd=5, events=POLLRDNORM}], 1, 100) = 0 (Timeout) ``` The write(1,... ) is debugging output. The nanosleep was intended to see if sleeping a bit before polling would help. Note that the write(5, ...) and the poll() come from different threads. Note that using two descriptors from a pipe() (which I do for other platforms) is fine, so this is some kind of issue specific to eventfd. Also, trying to reproduce this with a simpler single threaded program did not succeed. I'm wondering if there is some underlying cache synchronization problem? I'm testing this in a VMware Fusion virtual machine (Fusion 10.1.1) running on 2017 macbook pro (underlying OS is macOS 10.13). For now I'm going to switch back to pipes, since eventfd() seems unreliable -- if you can spot anything obviously wrong about the system call sequence above, I'd love to hear it. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1761619/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
