Re: Dcache oops

Al Viro
2016-06-03T21:46:35Z

On Fri, Jun 03, 2016 at 05:17:06PM -0400, Oleg Drokin wrote:

> > Can the same thing be reproduced (with NFS fix) on v4.6, ede4090, 7f427d3,
> > 4e8440b?
>
> Well, that was faster than I expected. 4e8440b triggers right away, so I guess
> there's no point in trying the later ones?
> BTW, just to confirm you are noticing - this is a DEBUG_PAGEALLOC build,
> so all freed memory is unmapped which is likely causing this oops - as a sign
> of use after free.

> [ 54.990119] BUG: unable to handle kernel paging request at ffff8800d2b7f000

Again a page-aligned nd->last.name and even smaller nd->last.len. It smells
like a page that used to contain a symlink body, but got freed under us.