All of lore.kernel.org
 help / color / mirror / Atom feed
From: Chris Wilson <chris@chris-wilson.co.uk>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Matthew Wilcox <willy@infradead.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Hugh Dickins <hughd@google.com>,
	Jan Kara <jack@suse.cz>, Song Liu <liu.song.a23@gmail.com>
Subject: Re: [PATCH v4] page cache: Store only head pages in i_pages
Date: Wed, 12 Jun 2019 08:42:05 +0100	[thread overview]
Message-ID: <156032532526.2193.13029744217391066047@skylake-alporthouse-com> (raw)
In-Reply-To: <20190612014634.f23fjumw666jj52s@box>

Quoting Kirill A. Shutemov (2019-06-12 02:46:34)
> On Sun, Jun 02, 2019 at 10:47:35PM +0100, Chris Wilson wrote:
> > Quoting Matthew Wilcox (2019-03-07 15:30:51)
> > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > > index 404acdcd0455..aaf88f85d492 100644
> > > --- a/mm/huge_memory.c
> > > +++ b/mm/huge_memory.c
> > > @@ -2456,6 +2456,9 @@ static void __split_huge_page(struct page *page, struct list_head *list,
> > >                         if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
> > >                                 shmem_uncharge(head->mapping->host, 1);
> > >                         put_page(head + i);
> > > +               } else if (!PageAnon(page)) {
> > > +                       __xa_store(&head->mapping->i_pages, head[i].index,
> > > +                                       head + i, 0);
> > 
> > Forgiving the ignorant copy'n'paste, this is required:
> > 
> > +               } else if (PageSwapCache(page)) {
> > +                       swp_entry_t entry = { .val = page_private(head + i) };
> > +                       __xa_store(&swap_address_space(entry)->i_pages,
> > +                                  swp_offset(entry),
> > +                                  head + i, 0);
> >                 }
> >         }
> >  
> > The locking is definitely wrong.
> 
> Does it help with the problem, or it's just a possible lead?

It definitely solves the problem we encountered of the bad VM_PAGE
leading to RCU stalls in khugepaged. The locking is definitely wrong
though :)
-Chris

  reply	other threads:[~2019-06-12  7:42 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-07 15:30 Matthew Wilcox
2019-06-01  9:26 ` Chris Wilson
2019-06-01 11:44   ` Chris Wilson
2019-06-02 10:51     ` Matthew Wilcox
2019-06-02 13:11       ` Chris Wilson
2019-06-02 19:28       ` Chris Wilson
2019-06-02 21:47 ` Chris Wilson
2019-06-12  1:46   ` Kirill A. Shutemov
2019-06-12  7:42     ` Chris Wilson [this message]
2019-06-19 10:04       ` Chris Wilson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=156032532526.2193.13029744217391066047@skylake-alporthouse-com \
    --to=chris@chris-wilson.co.uk \
    --cc=akpm@linux-foundation.org \
    --cc=hughd@google.com \
    --cc=jack@suse.cz \
    --cc=kirill@shutemov.name \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=liu.song.a23@gmail.com \
    --cc=willy@infradead.org \
    --subject='Re: [PATCH v4] page cache: Store only head pages in i_pages' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.