On Sun, Feb 14, 2016 at 01:51:20PM -0600, Michael Welling wrote: > On Sun, Feb 14, 2016 at 11:05:15AM -0800, Greg KH wrote: > > On Sun, Feb 14, 2016 at 06:56:20PM +0100, Linus Walleij wrote: > > > On Sun, Feb 14, 2016 at 6:49 PM, Greg KH <[email protected]> > > > wrote: > > > > On Sun, Feb 14, 2016 at 06:42:11PM +0100, Linus Walleij wrote: > > > >> Greg, heads-up on this... you'd know if this happened > > > >> before. > > > >> > > > >> On Sun, Feb 14, 2016 at 9:06 AM, Michael Welling <[email protected]> > > > >> 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. > > > > > > > > That device major is assigned to Infiniband, why shouldn't it be doing > > > > this? > > > > > > I mean it's annoying that they collide. (Because of the details I > > > write below, it's fine it's using the assigned number. > > > > > > > Why not just ask for a new reserved one? We could give you 261 and > > > > everything should be fine, right? > > > > > > Sure I can post a patch for that, but it just mitigates the problem. > > > > > > The report point to the serious problem that on this system > > > some dynamic allocations have already stolen major device > > > numbers 232 thru 255, and 232 and 233 are also assigned. > > > > > > What do you think about a patch that makes fs/char_dev.c > > > emit a warning when it starts assigning dynamic numbers > > > 233 and below? > > > > That's fine with me. I also think maybe we should look into just > > switching all char major/minor allocation to be dynamic, starting at the > > bottom and moving up. I think the only tools that might have an issue > > with that is the raw device controller, but maybe that has been fixed up > > in userspace, I haven't looked at that in many years. > > > > Is there any reason for the CHRDEV_MAJOR_HASH_SIZE being 255? > If we increase the size to say 511 will it break userspace?
No, that's an internal thing, but I don't see what that has to do with this... > In the future I see a robot building a kernel with more that 255 devices and > having to deal with this kind of collision again. We handle major numbers larger than 255 already... > The handling of large major assignment baffles me. It's tricky, messy, and something you don't want to touch, seriously... good luck, greg k-h
