linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] mm/hugetlb: make hugetlb_lock irq safe
Date: Wed, 5 Sep 2018 16:07:37 -0700	[thread overview]
Message-ID: <20180905230737.GA14977@bombadil.infradead.org> (raw)
In-Reply-To: <20180905150008.59d477c1f78f966a8f9c3cc8@linux-foundation.org>

On Wed, Sep 05, 2018 at 03:00:08PM -0700, Andrew Morton wrote:
> On Wed, 5 Sep 2018 14:35:11 -0700 Mike Kravetz <mike.kravetz@oracle.com> wrote:
> 
> > >                                            so perhaps we could put some
> > > stopgap workaround into that site and add a runtime warning into the
> > > put_page() code somewhere to detect puttage of huge pages from hardirq
> > > and softirq contexts.
> > 
> > I think we would add the warning/etc at free_huge_page.  The issue would
> > only apply to hugetlb pages, not THP.
> > 
> > But, the more I think about it the more I think Aneesh's patch to do
> > spin_lock/unlock_irqsave is the right way to go.  Currently, we only
> > know of one place where a put_page of hugetlb pages is done from softirq
> > context.  So, we could take the spin_lock/unlock_bh as Matthew suggested.
> > When the powerpc iommu code was added, I doubt this was taken into account.
> > I would be afraid of someone adding put_page from hardirq context.
> 
> Me too.  If we're going to do this, surely we should make hugepages
> behave in the same fashion as PAGE_SIZE pages.

But these aren't vanilla hugepages, they're specifically hugetlbfs pages.
I don't believe there's any problem with calling put_page() on a normally
allocated huge page or THP.

  reply	other threads:[~2018-09-05 23:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-05 11:23 [RFC PATCH] mm/hugetlb: make hugetlb_lock irq safe Aneesh Kumar K.V
2018-09-05 13:04 ` Matthew Wilcox
2018-09-05 13:26   ` Aneesh Kumar K.V
2018-09-05 13:48     ` Matthew Wilcox
2018-09-05 19:58       ` Andrew Morton
2018-09-05 21:35         ` Mike Kravetz
2018-09-05 22:00           ` Andrew Morton
2018-09-05 23:07             ` Matthew Wilcox [this message]
2018-09-05 23:51               ` Mike Kravetz
2018-09-06  4:03                 ` Aneesh Kumar K.V
2018-09-06 11:19                 ` Michal Hocko
2018-09-06  3:58           ` Aneesh Kumar K.V
2018-09-06  3:54         ` Aneesh Kumar K.V
2018-09-06  4:00       ` Aneesh Kumar K.V

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=20180905230737.GA14977@bombadil.infradead.org \
    --to=willy@infradead.org \
    --cc=akpm@linux-foundation.org \
    --cc=aneesh.kumar@linux.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mike.kravetz@oracle.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).