From: Miklos Szeredi <miklos@szeredi.hu>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
Al Viro <viro@zeniv.linux.org.uk>, Linux MM <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
overlayfs <linux-unionfs@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Colin Walters <walters@verbum.org>,
Andrew Morton <akpm@linux-foundation.org>,
syzbot <syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: [PATCH v4 1/2] hugetlb: use f_mode & FMODE_HUGETLBFS to identify hugetlbfs files
Date: Mon, 15 Jun 2020 15:01:37 +0200 [thread overview]
Message-ID: <CAJfpegs-Ch5ua658UD5s4u6ynKGpMzdiY31G-c4Fdu_=ZCV_uA@mail.gmail.com> (raw)
In-Reply-To: <CAOQ4uxgA+_4_UtVz17_eJL6m0CsDEVuiriBj1ZOkho+Ub1yuSA@mail.gmail.com>
On Mon, Jun 15, 2020 at 12:05 PM Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Mon, Jun 15, 2020 at 10:53 AM Miklos Szeredi <miklos@szeredi.hu> wrote:
> >
> > On Sat, Jun 13, 2020 at 9:12 PM Mike Kravetz <mike.kravetz@oracle.com> wrote:
> > >
> > > On 6/12/20 11:53 PM, Amir Goldstein wrote:
> >
> > > As a hugetlbfs developer, I do not know of a use case for interoperability
> > > with overlayfs. So yes, I am not too interested in making them work well
> > > together. However, if there was an actual use case I would be more than
> > > happy to consider doing the work. Just hate to put effort into fixing up
> > > two 'special' filesystems for functionality that may not be used.
> > >
> > > I can't speak for overlayfs developers.
> >
> > As I said, I only know of tmpfs being upper layer as a valid use case.
> > Does that work with hugepages? How would I go about testing that?
>
> Simple, after enabling CONFIG_HUGETLBFS:
>
> diff --git a/mount_union.py b/mount_union.py
> index fae8899..4070c70 100644
> --- a/mount_union.py
> +++ b/mount_union.py
> @@ -15,7 +15,7 @@ def mount_union(ctx):
> snapshot_mntroot = cfg.snapshot_mntroot()
> if cfg.should_mount_upper():
> system("mount " + upper_mntroot + " 2>/dev/null"
> - " || mount -t tmpfs upper_layer " + upper_mntroot)
> + " || mount -t hugetlbfs upper_layer " + upper_mntroot)
> layer_mntroot = upper_mntroot + "/" + ctx.curr_layer()
> upperdir = layer_mntroot + "/u"
> workdir = layer_mntroot + "/w"
>
> It fails colossally, because hugetlbfs, does not have write_iter().
> It is only meant as an interface to create named maps of huge pages.
> So I don't really see the use case for using it as upper.
Right.
I was actually asking about the tmpfs+hugepages, not the hugetlbfs case.
In the tmpfs case it looks like the lack of ->get_unmapped_area() in
overlayfs could still be an issue. But I'm not sure how to trigger
that.
Thanks,
Miklos
next prev parent reply other threads:[~2020-06-15 13:02 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-12 0:46 [PATCH v4 1/2] hugetlb: use f_mode & FMODE_HUGETLBFS to identify hugetlbfs files Mike Kravetz
2020-06-12 0:46 ` [PATCH v4 2/2] ovl: call underlying get_unmapped_area() routine. propogate FMODE_HUGETLBFS Mike Kravetz
2020-06-14 12:50 ` Amir Goldstein
2020-06-12 1:53 ` [PATCH v4 1/2] hugetlb: use f_mode & FMODE_HUGETLBFS to identify hugetlbfs files Matthew Wilcox
2020-06-12 1:58 ` Al Viro
2020-06-12 21:51 ` Mike Kravetz
2020-06-13 6:53 ` Amir Goldstein
2020-06-13 14:38 ` Matthew Wilcox
2020-06-13 19:12 ` Mike Kravetz
2020-06-15 7:53 ` Miklos Szeredi
2020-06-15 10:05 ` Amir Goldstein
2020-06-15 13:01 ` Miklos Szeredi [this message]
2020-06-15 23:45 ` Mike Kravetz
2020-06-16 9:01 ` Miklos Szeredi
2020-06-15 8:24 ` Miklos Szeredi
2020-06-15 17:48 ` Mike Kravetz
2020-06-12 6:28 ` [RFC PATCH] hugetlb: hugetlbfs_file_operations can be static kernel test robot
2020-06-13 14:19 ` [hugetlb] 5156c6c1b9: INFO:trying_to_register_non-static_key kernel test robot
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='CAJfpegs-Ch5ua658UD5s4u6ynKGpMzdiY31G-c4Fdu_=ZCV_uA@mail.gmail.com' \
--to=miklos@szeredi.hu \
--cc=akpm@linux-foundation.org \
--cc=amir73il@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-unionfs@vger.kernel.org \
--cc=mike.kravetz@oracle.com \
--cc=syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=viro@zeniv.linux.org.uk \
--cc=walters@verbum.org \
--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).