On 03/17, Andy Lutomirski wrote: > > On Tue, Mar 17, 2015 at 6:43 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > > > > But at least the bug exposed by the test-case looks clear: > > > > do_linear_fault: > > > > vmf->pgoff = (((address & PAGE_MASK) - vma->vm_start) >> PAGE_SHIFT) > > + vma->vm_pgoff; > > ... > > > > special_mapping_fault: > > > > pgoff = vmf->pgoff - vma->vm_pgoff; > > > > > > So special_mapping_fault() can only work if this mapping starts from the > > first page in ->pages[]. > > > > So perhaps we need _something like_ the (wrong/incomplete) patch below... > > > > Or, really, perhaps we can create vdso_mapping ? So that map_vdso() could > > simply mmap the anon_inode file... > > That's slightly tricky, I think, because it could start showing up in > /proc/PID/map_files or whatever it's called, and I don't think we want > that. Hmm. To me this looke liks improvement. And again, with this change uprobe-in-vdso can work. OK, this is off-topic right now, lets forget this for the moment. > Your patch does look like a considerable improvement, though. Let me > see if I can find some time to fold it in with the rest of my special > mapping rework over the next few days. I'll try to recheck... Perhaps I'll send this (changed) patch for review. This is a bugfix, even if the bug is minor. And note that with this change vvar->access() becomes trivial. I think it makes sense to fix "gup() fails in vvar" too. Gdb developers have enough other problems with the poor kernel interfaces ;) Oleg. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>