Re: [PATCH v8 23/70] mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()

From: Liam Howlett <liam.howlett@oracle.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>,
	"maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Yu Zhao <yuzhao@google.com>, Juergen Gross <jgross@suse.com>
Subject: Re: [PATCH v8 23/70] mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()
Date: Mon, 2 May 2022 00:14:21 +0000	[thread overview]
Message-ID: <20220502001358.s2azy37zcc27vgdb@revolver> (raw)
In-Reply-To: <20220428181621.636487e753422ad0faf09bd6@linux-foundation.org>

* Andrew Morton <akpm@linux-foundation.org> [220428 21:16]:
> On Fri, 29 Apr 2022 00:38:50 +0000 Liam Howlett <liam.howlett@oracle.com> wrote:
> 
> > > mm/mmap.c: In function 'do_brk_flags':
> > > mm/mmap.c:2908:17: error: implicit declaration of function
> > > 	'khugepaged_enter_vma_merge'; did you mean 'khugepaged_enter_vma'?
> > > 
> > > It appears that this is later fixed, but it hurts bisectability
> > > (and prevents me from finding the actual build failure in linux-next
> > > when trying to build corenet64_smp_defconfig).
> > 
> > Yeah, that khugepaged_enter_vma_merge was renamed in another patch set.
> > Andrew made the correction but kept the patch as it was.  I think the
> > suggested change is right.. if you read the commit that introduced
> > khugepaged_enter_vma(), it seems right at least.
> 
> Things are a bit crazy lately.  Merge issues with mapletree, merge
> issues with mglru on mapletree, me doing a bunch of retooling to start
> publishing/merging via git, mapletree runtime issues, etc.
> 
> I've dropped the mapletree patches again.  Please scoop up all known
> fixes and redo against the (non-rebasing) mm-stable branch at
> git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Okay, sounds good.

I have been porting my patches over and hit a bit of a snag. It looked
like my patches were not booting on the s390 - but not all the time. So
I reverted back to mm-stable (059342d1dd4e) and found that also failed
to boot sometimes on my qemu setup.  When it fails it's ~4-5sec into
booting.  The last thing I see is:

"[    4.668916] Spectre V2 mitigation: execute trampolines"

I've bisected back to commit e553f62f10d9 (mm, page_alloc: fix
build_zonerefs_node())

With the this commit, I am unable to boot one out of three times.  When
using the previous commit I was not able to get it to hang after trying
10+ times.  This is a qemu s390 install with KASAN on and I see no error
messages.  I think it's likely it is this patch, but no guaranteed.

Thanks,
Liam

> 
> The mm-unstable branch is a rebasing tree which contains mm-stable as
> well as all the quilt-based MM material which isn't final enough to get
> into mm-stable.  So before sending please do a test merge with mm-unstable,
> evaluate any issues which might be encountered.
> 
> I'd prefer to concentrate on getting mapletree stabilized and landed
> for now, worry about mglru after that.
> 