Re: [PATCH] mm/gup: fix always draining LRU caches in collect_longterm_unpinnable_folios()

[Andrew Morton]

On Thu, 6 Aug 2026 18:29:39 +0200 "David Hildenbrand (Arm)" <david@xxxxxxxxxx> wrote:

> On 8/1/26 21:20, Andrew Morton wrote:
> > On Sat, 1 Aug 2026 11:49:39 -0700 (PDT) Hugh Dickins <hughd@xxxxxxxxxx> wrote:
> > 
> >>> Found by code inspection. If someone has a testcase that can easily
> >>> trigger this and result in migration problems, please test! But this
> >>> change seems to be "obvious the right thing to do".
> >>
> >> Sorry, I don't (as perhaps is too obvious). And I'm a wee bit afraid
> >> that some of the problems which those changes happened to succeed in
> >> fixing, might now reappear once the drains are finely targeted.
> >>
> >> Am I arguing for a delay before advancing to stable?  Perhaps, but
> >> I think not: it's probably best to get that working as intended,
> >> then deal with any fallout if it arises: just be on guard.
> > 
> > This patch is in mm-new, so it's still some months away from -stable
> > eligibility.
> 
> I hope you meant weeks :)

I was unclear.  The patch is (now) in mm-unstable, aimed at 7.3-rc1. 
But I don't expect it to be released in -stable kernels for some time
after we've added it to 7.3-rc1.

I don't know what the latency is, really.  Seems to take a week or
three for Greg to grab these things, but how much longer it takes for
it to get into the 7.2.x and earlier kernels is probably quite
variable.

> Can we get that into 7.3-rc1, though? There is quite the overlap with
> guest_memfd work, and I'll send another patch that depends on this.

Yep.  In the second-week-of-merge-window batch.