On 11/12/2020 7:33 PM, Ira Weiny wrote:
So I think the final point is the key to fixing the bug. Keeping any current->mm which is not the one we opened the file with... (or more specifically the one which first registered memory). In some ways this may be worse than before because technically the parent could open the fd and hand it to the child and have the child register with it's mm. But that is ok really... May just be odd behavior for some users depending on what operations they do and in what order.
I don't think that's worse than before. Before we were letting it operate on the wrong mm. That's so much worse. Yes, parent could open fd and hand it off, which is OK. The "odd" behavior is up to whoever wrote the user space code to do that in the first place.
[1] Also, you probably should credit Jann for the idea with a suggested by tag.
Will change reported-by to suggested-by. -Denny
