On Thu, May 26, 2022 at 05:40:44PM -0700, Ira Weiny wrote: > On Thu, May 26, 2022 at 03:48:28PM +0100, Matthew Wilcox wrote: > > > > I was looking at memmove_page() and it occurred to me that it can't > > actually work, > > Oh wow yea. Because you can't unmap that address correctly. I don't understand what you mean ... you can unmap the address, it's just that memmove can't know that the two virtual ranges actually overlap physically. > Yes deletion is best. But... > > copy_user_highpage() > copy_highpage() > > ... might suffer from the same potential issue should a user not realize. I > think memcpy_page() by virtue of the name. Umm? They're all using memcpy(), so the caller must guarantee that the physical addresses are different. > I could not say anything at LSFmm because the Outreachy interns had not been > announced but I've selected Fabio to help with the highmem rework through that > program. Excellent! I advised Fabio last year, and I think he'll do a sterling job this year. > Would you like Fabio or I to send a patch? I think the main thing right now is > to just drop the memmove_page() Sure, just stick my Reported-by: on it.
