On Mon, Dec 08, 2014 at 10:23:26AM -0800, Linus Torvalds wrote: > Did this actually use to work? Or is it an issue of "the new iov_iter > is so generic that something that used to just return an error now > 'works' and triggers the problem"? Looks like it failed with EINVAL. Which might very well be the sane reaction - if we run into a vmalloc/module address, act as if we failed to get that page and exit the loop. > > What's the sane way to grab struct page * for a vmalloc'ed address? > > So "vmalloc_to_page()" should work. > > However, it's actually fundamentally racy unless you can guarantee > that the vmalloc()'ed area in question is stable (so you had better > have done that allocation yourself, and be in control of the freeing, > rather than "we look up random vmalloc'ed addresses). If vfree(buffer) races with kernel_read() into buffer, we are so badly fucked that stability of pointers to pages is the least of our concerns... > In general, it's really a horrible thing to use, and tends to be a big > red sign that "somebody misdesigned this badly" More like "nobody has thought of that case", at a guess, but then I hadn't been involved in finit_module() design - I don't even remember the discussions around it. That would be what, something circa 3.7? -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
