Greg, heads-up on this... you'd know if this happened before. On Sun, Feb 14, 2016 at 9:06 AM, Michael Welling <mwell...@ieee.org> wrote: > On Sun, Feb 14, 2016 at 02:59:06PM +0800, kernel test robot wrote: >> FYI, we noticed the below changes on >> >> https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git chardev >> commit 3c702e9987e261042a07e43460a8148be254412e ("gpio: add a userspace >> chardev ABI for GPIOs") >> >> >> [ 1.951191] user_verbs: couldn't register device number > > Looks like user_verbs is using a static device node setup. > > enum { > IB_UVERBS_MAJOR = 231, > IB_UVERBS_BASE_MINOR = 192, > IB_UVERBS_MAX_DEVICES = 32 > }; > > #define IB_UVERBS_BASE_DEV MKDEV(IB_UVERBS_MAJOR, IB_UVERBS_BASE_MINOR)
That's annoying... I notice that infiniband is using register_chrdev_region() at module_init() time, counting on device major 231 to be free. > Something tells me that a new GPIO chardev is taking this spot. Yes. Please post the contents of /proc/devices on this system. If you look in fs/char_dev.c this happens in __register_chrdev_region() you can see that dynamic character major numbers are assigned from 254 and downwards in this way: #define CHRDEV_MAJOR_HASH_SIZE 255 (...) } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; /* temporary */ if (major == 0) { for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) { if (chrdevs[i] == NULL) break; } if (i == 0) { ret = -EBUSY; goto out; } major = i; } Whereas fixed device numbers are assigned sparsely from low to high. I suspect what happens is that in your system there are already so many dynamically assigned character devices that they go down and already collide with 232 and 233, you just didn't notice until this make it hit 231 which incidentally was in use. So I would be very intersted in what misc stuff you have filling out 232 thru 255, already knocking out other assigned numbers... I guess I *could* try to grab a static assignment in the low range, say recycle character device 8, which is the first unallocated from the bottom, but I'm afraid the device core maintainers have worked to get devices to go more dynamic and would be very unhappy about this. Yours, Linus Walleij