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From:   Yang Shi <shy828301@gmail.com>
Date:   Mon, 16 Aug 2021 13:24:25 -0700
Message-ID: <CAHbLzkoE6h9dmRp6zfaKdLjq2y24+PV-yBUv6RMXtzKvPFdBkw@mail.gmail.com>
Subject: Re: [PATCH 1/2] mm: hwpoison: don't drop slab caches for offlining
 non-LRU page
To:     Matthew Wilcox <willy@infradead.org>
Cc:     =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= 
        <naoya.horiguchi@nec.com>, Oscar Salvador <osalvador@suse.de>,
        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>
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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.