Re: 4.19.5 and later has tons of false messages "BUG: non-zero pgtables_bytes on freeing mm: -16384"

From: Sasha Levin
Date: Thu Dec 27 2018 - 16:01:41 EST

On Thu, Dec 27, 2018 at 10:28:56AM +0100, Christian Borntraeger wrote:

On 27.12.2018 10:13, Christian Borntraeger wrote:

Right now you get a message
"BUG: non-zero pgtables_bytes on freeing mm: -16384"
for EVERY process that exits in 4.19.5 and later.

bisect points to
commit 4136161d676a93fc8df6bdb80d720c15522d6c24
Author: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Date: Mon Oct 15 11:09:16 2018 +0200

s390/mm: fix mis-accounting of pgtable_bytes

[ Upstream commit e12e4044aede97974f2222eb7f0ed726a5179a32 ]

Turns out that this patch requires several dependencies so the autoselection of this
patch was missing that.

Can we either revert this patch or add the dependencies?


It seems that adding

commit 6d212db11947ae5464e4717536ed9faf61c01e86 ("mm: add mm_pxd_folded checks to pgtable_bytes accounting functions")
fixes the issue.

I've queued 6d212db11947 for 4.19 for now, thank you.