Messages in this thread | | | From | Linus Torvalds <> | Date | Sun, 27 Dec 2020 15:40:36 -0800 | Subject | Re: [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting |
| |
On Sun, Dec 27, 2020 at 3:12 PM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > Ok, your fix for that folded in, and here's yet another version.
Still not good.
I don't know what happened, but the change of
- vm_fault_t ret = 0; + vm_fault_t ret;
is very very wrong. The next user is
+ if (!(vma->vm_flags & VM_SHARED)) + ret = check_stable_address_space(vma->vm_mm); + if (ret) + return ret;
so now 'ret' will potentially be used uninitialized (although this is the kind of thing that a compiler might almost accidentally end up fixing - with a single dominating assignment, I could imagine the compiler moving the test to that assignment and thus "fixing" the code without really even meaning to).
I think Kirill was intending to move the "if (ret)" up into the path that sets it, IOW something like
+ if (!(vma->vm_flags & VM_SHARED)) { + ret = check_stable_address_space(vma->vm_mm); + if (ret) + return ret; + }
instead. But that patch as-is is broken.
Kirill?
Linus
| |