Re: [PATCH 1/2] mm: hwpoison: don't drop slab caches for offlining non-LRU page

From: "HORIGUCHI NAOYA(堀口　直也)" <naoya.horiguchi@nec.com>
To: Yang Shi <shy828301@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>,
	Oscar Salvador <osalvador@suse.de>,
	"tdmackey@twitter.com" <tdmackey@twitter.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>, Linux MM <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm: hwpoison: don't drop slab caches for offlining non-LRU page
Date: Wed, 18 Aug 2021 05:02:39 +0000	[thread overview]
Message-ID: <20210818050239.GA496938@hori.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <CAHbLzkoE6h9dmRp6zfaKdLjq2y24+PV-yBUv6RMXtzKvPFdBkw@mail.gmail.com>

On Mon, Aug 16, 2021 at 01:24:25PM -0700, Yang Shi wrote:
> On Mon, Aug 16, 2021 at 12:38 PM Matthew Wilcox <willy@infradead.org> wrote:
> >
> > On Mon, Aug 16, 2021 at 11:09:08AM -0700, Yang Shi wrote:
> > > But the most disappointing thing is all the effort doesn't make the page
> > > offline, it just returns:
> > >
> > > soft_offline: 0x1469f2: unknown non LRU page type 5ffff0000000000 ()
> >
> > It's a shame it doesn't call dump_page().  There might be more
> > interesting information somewhere in struct page that would help us
> > figure out what kind of page it was in your environment.  For example,
> > it might be a page table page or a page allocated for vmalloc(), and
> > in both those cases, there are things we might be able to do (we'd
> > certainly be able to figure out that it isn't worth shrinking slab!)
> 
> Yes,  dump_page() could provide more information to us. I could add a
> new patch or just update this patch to call dump_page() if offline is
> failed if the hwpoison maintainer agrees to this as well.

I agree with showing more information in failure case. Thanks for the input.

- Naoya Horiguchi