Hi, as I'm sure most of you are aware of, every URB submission triggers a small memory allocation in the host controller. On top of that it might be run in atomic context. This has always seemed to me as a possible source of very hard to reproduce and potentially nasty issues. For example I'm thinking of embedded systems driving some critical operation through USB. I wonder if anyone has been able to log any failure on that area. I was unable to find anything on the relevant bugzillas, nor by talking with some knowledgeable people. Note that some drivers actively protect themselves from URB submission failures, taking care to resubmit them (see usbhid/hid-core.c). Making the allocation fail on some controlled test system seems feasible (it might not be that easy, it really depends on how realistic you want to be). But it might be pointless without a real life failure scenario. Regards, Nicolas
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