From: kirill.shutemov@linux.intel.com
To: Ackerley Tng <ackerleytng@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
kvm@vger.kernel.org, linux-api@vger.kernel.org,
linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, qemu-devel@nongnu.org,
chao.p.peng@linux.intel.com, aarcange@redhat.com,
ak@linux.intel.com, akpm@linux-foundation.org, arnd@arndb.de,
bfields@fieldses.org, bp@alien8.de, corbet@lwn.net,
dave.hansen@intel.com, david@redhat.com, ddutile@redhat.com,
dhildenb@redhat.com, hpa@zytor.com, hughd@google.com,
jlayton@kernel.org, jmattson@google.com, joro@8bytes.org,
jun.nakajima@intel.com, linmiaohe@huawei.com, luto@kernel.org,
mail@maciej.szmigiero.name, mhocko@suse.com,
michael.roth@amd.com, mingo@redhat.com, naoya.horiguchi@nec.com,
pbonzini@redhat.com, qperret@google.com, rppt@kernel.org,
seanjc@google.com, shuah@kernel.org, steven.price@arm.com,
tabba@google.com, tglx@linutronix.de, vannapurve@google.com,
vbabka@suse.cz, vkuznets@redhat.com, wanpengli@tencent.com,
wei.w.wang@intel.com, x86@kernel.org, yu.c.zhang@linux.intel.com
Subject: Re: [RFC PATCH 1/2] mm: restrictedmem: Allow userspace to specify mount_path for memfd_restricted
Date: Fri, 24 Feb 2023 12:36:00 +0300 [thread overview]
Message-ID: <20230224093600.osmbpilmsi64wlwb@box.shutemov.name> (raw)
In-Reply-To: <diqzsfex5hfv.fsf@ackerleytng-cloudtop.c.googlers.com>
On Thu, Feb 23, 2023 at 12:55:16AM +0000, Ackerley Tng wrote:
>
> "Kirill A. Shutemov" <kirill@shutemov.name> writes:
>
> > On Thu, Feb 16, 2023 at 12:41:16AM +0000, Ackerley Tng wrote:
> > > By default, the backing shmem file for a restrictedmem fd is created
> > > on shmem's kernel space mount.
>
> > > With this patch, an optional tmpfs mount can be specified, which will
> > > be used as the mountpoint for backing the shmem file associated with a
> > > restrictedmem fd.
>
> > > This change is modeled after how sys_open() can create an unnamed
> > > temporary file in a given directory with O_TMPFILE.
>
> > > This will help restrictedmem fds inherit the properties of the
> > > provided tmpfs mounts, for example, hugepage allocation hints, NUMA
> > > binding hints, etc.
>
> > > Signed-off-by: Ackerley Tng <ackerleytng@google.com>
> > > ---
> > > include/linux/syscalls.h | 2 +-
> > > include/uapi/linux/restrictedmem.h | 8 ++++
> > > mm/restrictedmem.c | 63 +++++++++++++++++++++++++++---
> > > 3 files changed, 66 insertions(+), 7 deletions(-)
> > > create mode 100644 include/uapi/linux/restrictedmem.h
>
> > > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> > > index f9e9e0c820c5..4b8efe9a8680 100644
> > > --- a/include/linux/syscalls.h
> > > +++ b/include/linux/syscalls.h
> > > @@ -1056,7 +1056,7 @@ asmlinkage long sys_memfd_secret(unsigned int
> > > flags);
> > > asmlinkage long sys_set_mempolicy_home_node(unsigned long start,
> > > unsigned long len,
> > > unsigned long home_node,
> > > unsigned long flags);
> > > -asmlinkage long sys_memfd_restricted(unsigned int flags);
> > > +asmlinkage long sys_memfd_restricted(unsigned int flags, const char
> > > __user *mount_path);
>
> > > /*
> > > * Architecture-specific system calls
>
> > I'm not sure what the right practice now: do we provide string that
> > contains mount path or fd that represents the filesystem (returned from
> > fsmount(2) or open_tree(2)).
>
> > fd seems more flexible: it allows to specify unbind mounts.
>
> I tried out the suggestion of passing fds to memfd_restricted() instead
> of strings.
>
> One benefit I see of using fds is interface uniformity: it feels more
> aligned with other syscalls like fsopen(), fsconfig(), and fsmount() in
> terms of using and passing around fds.
>
> Other than being able to use a mount without a path attached to the
> mount, are there any other benefits of using fds over using the path string?
It would be nice if anyone from fs folks comment on this.
> Should I post the patches that allows specifying a mount using fds?
> Should I post them as a separate RFC, or as a new revision to this RFC?
Let's first decide what the right direction is.
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2023-02-24 9:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-16 0:41 [RFC PATCH 0/2] Providing mount for memfd_restricted() syscall Ackerley Tng
2023-02-16 0:41 ` [RFC PATCH 1/2] mm: restrictedmem: Allow userspace to specify mount_path for memfd_restricted Ackerley Tng
2023-02-16 10:01 ` Kirill A. Shutemov
2023-02-23 0:55 ` Ackerley Tng
2023-02-24 9:36 ` kirill.shutemov [this message]
2023-02-16 0:41 ` [RFC PATCH 2/2] selftests: restrictedmem: Check hugepage-ness of shmem file backing restrictedmem fd Ackerley Tng
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=20230224093600.osmbpilmsi64wlwb@box.shutemov.name \
--to=kirill.shutemov@linux.intel.com \
--cc=aarcange@redhat.com \
--cc=ackerleytng@google.com \
--cc=ak@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=bfields@fieldses.org \
--cc=bp@alien8.de \
--cc=chao.p.peng@linux.intel.com \
--cc=corbet@lwn.net \
--cc=dave.hansen@intel.com \
--cc=david@redhat.com \
--cc=ddutile@redhat.com \
--cc=dhildenb@redhat.com \
--cc=hpa@zytor.com \
--cc=hughd@google.com \
--cc=jlayton@kernel.org \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=jun.nakajima@intel.com \
--cc=kirill@shutemov.name \
--cc=kvm@vger.kernel.org \
--cc=linmiaohe@huawei.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=mail@maciej.szmigiero.name \
--cc=mhocko@suse.com \
--cc=michael.roth@amd.com \
--cc=mingo@redhat.com \
--cc=naoya.horiguchi@nec.com \
--cc=pbonzini@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=qperret@google.com \
--cc=rppt@kernel.org \
--cc=seanjc@google.com \
--cc=shuah@kernel.org \
--cc=steven.price@arm.com \
--cc=tabba@google.com \
--cc=tglx@linutronix.de \
--cc=vannapurve@google.com \
--cc=vbabka@suse.cz \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
--cc=wei.w.wang@intel.com \
--cc=x86@kernel.org \
--cc=yu.c.zhang@linux.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).