Hello, Matthew. On Mon, Dec 12, 2016 at 05:35:17PM +0000, Matthew Wilcox wrote: > I know the preload followed by preload_end looks wrong. I don't > think it's broken though. If we get preempted, then the worst > situation is that we'll end up with the memory we preallocated being > allocated to somebody else. Then the attempt to allocate memory can > fail, and we'll return -EAGAIN, at which point all callers are > supposed to return to the pre_get() stage. Certainly that's what > ida_simple_get() does. Ah, right, ida_pre_get() doesn't have any protection against other task allocating inbetween pre_get and the actual allocation, so it should retry on failure. Yeah, then the proposed preloading wouldn't be wrong. It'd be nice to explain what's going on tho. > I'd definitely be open to changing the IDA API. I know Kent had > some thoughts on that including splitting the simple lock into a > per-IDA lock. His last work on it was here, I believe: > > https://evilpiepirate.org/git/linux-bcache.git/log/?h=idr Yeah, that was a big re-write, but for now I think it'd be nice to replace ida's pre_get mechanism with something similar to idr's preload so that they're more consistent. There aren't that many direct users of ida_pre_get(), so it shouldn't be too difficult to change. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
