On Tue, Apr 17, 2018 at 04:22:46PM +0200, Michal Hocko wrote:
On Tue 17-04-18 13:39:33, Sasha Levin wrote: [...]
But mm/ commits don't come only from these people. Here's a concrete example we can discuss:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
I would be really careful. Because that reqiures to audit all callers to be compliant with the change. This is just _too_ easy to backport without noticing a failure. Now consider the other side. Is there any real bug report backing this? This behavior was like that for quite some time but I do not remember any actual bug report and the changelog doesn't mention one either. It is about theoretical problem.
https://lkml.org/lkml/2018/3/19/430
There's even a fun little reproducer that allowed me to confirm it's an issue (at least) on 4.15.
Heck, it might even qualify as a CVE.
So if this was to be merged to stable then the changelog should contain a big fat warning about the existing users and how they should be checked.
So what I'm asking is why *wasn't* it sent to stable? Yes, it requires additional work backporting this, but what I'm saying is that this didn't happen at all.
Besides that I can see Reviewed-by: akpm and Andrew is usually very careful about stable backports so there probably _was_ a reson to exclude stable. -- Michal Hocko SUSE Labs