From: Ming Lei <ming.lei@redhat.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Michal Hocko <mhocko@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>, Minchan Kim <minchan@kernel.org>,
Rik van Riel <riel@redhat.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>
Subject: Re: [PATCH -mm] mm, swap: Fix THP swap out
Date: Mon, 24 Jun 2019 15:28:31 +0800 [thread overview]
Message-ID: <20190624072830.GA10539@ming.t460p> (raw)
In-Reply-To: <87imsvbnie.fsf@yhuang-dev.intel.com>
On Mon, Jun 24, 2019 at 12:44:41PM +0800, Huang, Ying wrote:
> Ming Lei <ming.lei@redhat.com> writes:
>
> > Hi Huang Ying,
> >
> > On Mon, Jun 24, 2019 at 10:23:36AM +0800, Huang, Ying wrote:
> >> From: Huang Ying <ying.huang@intel.com>
> >>
> >> 0-Day test system reported some OOM regressions for several
> >> THP (Transparent Huge Page) swap test cases. These regressions are
> >> bisected to 6861428921b5 ("block: always define BIO_MAX_PAGES as
> >> 256"). In the commit, BIO_MAX_PAGES is set to 256 even when THP swap
> >> is enabled. So the bio_alloc(gfp_flags, 512) in get_swap_bio() may
> >> fail when swapping out THP. That causes the OOM.
> >>
> >> As in the patch description of 6861428921b5 ("block: always define
> >> BIO_MAX_PAGES as 256"), THP swap should use multi-page bvec to write
> >> THP to swap space. So the issue is fixed via doing that in
> >> get_swap_bio().
> >>
> >> BTW: I remember I have checked the THP swap code when
> >> 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") was merged,
> >> and thought the THP swap code needn't to be changed. But apparently,
> >> I was wrong. I should have done this at that time.
> >>
> >> Fixes: 6861428921b5 ("block: always define BIO_MAX_PAGES as 256")
> >> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> >> Cc: Ming Lei <ming.lei@redhat.com>
> >> Cc: Michal Hocko <mhocko@kernel.org>
> >> Cc: Johannes Weiner <hannes@cmpxchg.org>
> >> Cc: Hugh Dickins <hughd@google.com>
> >> Cc: Minchan Kim <minchan@kernel.org>
> >> Cc: Rik van Riel <riel@redhat.com>
> >> Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
> >> ---
> >> mm/page_io.c | 7 ++-----
> >> 1 file changed, 2 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/mm/page_io.c b/mm/page_io.c
> >> index 2e8019d0e048..4ab997f84061 100644
> >> --- a/mm/page_io.c
> >> +++ b/mm/page_io.c
> >> @@ -29,10 +29,9 @@
> >> static struct bio *get_swap_bio(gfp_t gfp_flags,
> >> struct page *page, bio_end_io_t end_io)
> >> {
> >> - int i, nr = hpage_nr_pages(page);
> >> struct bio *bio;
> >>
> >> - bio = bio_alloc(gfp_flags, nr);
> >> + bio = bio_alloc(gfp_flags, 1);
> >> if (bio) {
> >> struct block_device *bdev;
> >>
> >> @@ -41,9 +40,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags,
> >> bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
> >> bio->bi_end_io = end_io;
> >>
> >> - for (i = 0; i < nr; i++)
> >> - bio_add_page(bio, page + i, PAGE_SIZE, 0);
> >
> > bio_add_page() supposes to work, just wondering why it doesn't recently.
>
> Yes. Just checked and bio_add_page() works too. I should have used
> that. The problem isn't bio_add_page(), but bio_alloc(), because nr ==
> 512 > 256, mempool cannot be used during swapout, so swapout will fail.
Then we can pass 1 to bio_alloc(), together with single bio_add_page()
for making the code more readable.
thanks,
Ming
next prev parent reply other threads:[~2019-06-24 7:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 2:23 [PATCH -mm] mm, swap: Fix THP swap out Huang, Ying
2019-06-24 3:34 ` Ming Lei
2019-06-24 4:44 ` Huang, Ying
2019-06-24 7:28 ` Ming Lei [this message]
2019-06-24 7:31 ` Huang, Ying
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=20190624072830.GA10539@ming.t460p \
--to=ming.lei@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=daniel.m.jordan@oracle.com \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=minchan@kernel.org \
--cc=riel@redhat.com \
--cc=ying.huang@intel.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).