Messages in this thread | | | Date | Wed, 22 May 2019 10:56:01 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation |
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On Wed, 22 May 2019, Oliver Neukum wrote:
> On Di, 2019-05-21 at 10:00 -0400, Alan Stern wrote: > > > > Changing configurations amounts to much the same as disconnecting, > > because both operations destroy all the existing interfaces. > > > > Disconnect can arise in two different ways. > > > > Physical hot-unplug: All I/O operations will fail. > > > > Rmmod or unbind: I/O operations will succeed. > > > > The second case is probably okay. The first we can do nothing about. > > However, in either case we do need to make sure that memory allocations > > do not require any writebacks. This suggests that we need to call > > memalloc_noio_save() from within usb_unbind_interface(). > > I agree with the problem, but I fail to see why this issue would be > specific to USB. Shouldn't this be done in the device core layer?
Only for drivers that are on the block-device writeback path. The device core doesn't know which drivers these are.
Alan Stern
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