From: Michal Hocko <mhocko@suse.com>
To: Rik van Riel <riel@surriel.com>
Cc: Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, Mel Gorman <mgorman@suse.de>,
Andrea Arcangeli <aarcange@redhat.com>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH] mm,thp,shmem: limit shmem THP alloc gfp_mask
Date: Fri, 23 Oct 2020 08:47:36 +0200 [thread overview]
Message-ID: <20201023064736.GQ23790@dhcp22.suse.cz> (raw)
In-Reply-To: <1b2d262c30bd839ac433587532a27ad800df4771.camel@surriel.com>
On Thu 22-10-20 12:06:01, Rik van Riel wrote:
> On Thu, 2020-10-22 at 17:50 +0200, Michal Hocko wrote:
> > On Thu 22-10-20 09:25:21, Rik van Riel wrote:
> > > On Thu, 2020-10-22 at 10:15 +0200, Michal Hocko wrote:
> > > > On Wed 21-10-20 23:48:46, Rik van Riel wrote:
> > > > >
> > > > > diff --git a/mm/shmem.c b/mm/shmem.c
> > > > > index 537c137698f8..d1290eb508e5 100644
> > > > > --- a/mm/shmem.c
> > > > > +++ b/mm/shmem.c
> > > > > @@ -1545,8 +1545,11 @@ static struct page
> > > > > *shmem_alloc_hugepage(gfp_t gfp,
> > > > > return NULL;
> > > > >
> > > > > shmem_pseudo_vma_init(&pvma, info, hindex);
> > > > > - page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY
> > > > > |
> > > > > __GFP_NOWARN,
> > > > > - HPAGE_PMD_ORDER, &pvma, 0,
> > > > > numa_node_id(),
> > > > > true);
> > > > > + /* Limit the gfp mask according to THP configuration.
> > > > > */
> > > > > + gfp |= __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN;
> > > >
> > > > What is the reason for these when alloc_hugepage_direct_gfpmask
> > > > provides
> > > > the full mask?
> > >
> > > The mapping_gfp_mask for the shmem file might have additional
> > > restrictions above and beyond the gfp mask returned by
> > > alloc_hugepage_direct_gfpmask, and I am not sure we should just
> > > ignore the mapping_gfp_mask.
> >
> > No, we shouldn't. But I do not see why you should be adding the above
> > set of flags on top.
>
> Because THP allocations are higher order and optimistic,
> and we want them to:
> 1) be annotated as compound allocations
> 2) fail (and fall back to 4kB allocations) when they cannot
> be easily satisfied, and
> 3) not create a spew of allocation failure backtraces on
> the (serial) console when these THP allocations fail
This all is already returned from alloc_hugepage_direct_gfpmask.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-10-23 6:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 3:48 [PATCH] mm,thp,shmem: limit shmem THP alloc gfp_mask Rik van Riel
2020-10-22 8:15 ` Michal Hocko
2020-10-22 13:25 ` Rik van Riel
2020-10-22 15:50 ` Michal Hocko
2020-10-22 16:06 ` Rik van Riel
2020-10-23 6:47 ` Michal Hocko [this message]
2020-10-22 14:51 ` Vlastimil Babka
2020-10-22 14:52 ` Vlastimil Babka
2020-10-22 16:00 ` Yu Xu
2020-10-22 16:40 ` Rik van Riel
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=20201023064736.GQ23790@dhcp22.suse.cz \
--to=mhocko@suse.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=hughd@google.com \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=riel@surriel.com \
--cc=willy@infradead.org \
/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).