[Bug 204407] New: Bad page state in process Xorg

[Matthew Wilcox]

On Fri, Aug 02, 2019 at 05:17:30PM -0400, Qian Cai wrote:
> On Fri, 2019-08-02 at 13:33 -0700, Matthew Wilcox wrote:
> > It occurs to me that when a page is freed, we could record some useful bits
> > of information in the page from the stack trace to help debug double-free 
> > situations.  Even just stashing __builtin_return_address in page->mapping
> > would be helpful, I think.
> 
> Sounds like need to enable "page_owner", so it will do  __dump_page_owner().

That doesn't help because we call reset_page_owner() in the free page path.

We could turn on tracing because we call trace_mm_page_free() in this
path.  That requires the reporter to be able to reproduce the problem,
and it's not clear to me whether this is a "happened once" or "every
time I do this, it happens" problem.