From: Jan Beulich <jbeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
stable@vger.kernel.org, Sander Eikelenboom <linux@eikelenboom.it>,
xen-devel@lists.xenproject.org, x86@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] xen: fix usage of pmd/pud_poplulate in mremap for pv guests
Date: Wed, 8 Sep 2021 13:07:59 +0200 [thread overview]
Message-ID: <5a4859db-d173-88dd-5ea9-dd5fd893d934@suse.com> (raw)
In-Reply-To: <20210908073640.11299-1-jgross@suse.com>
On 08.09.2021 09:36, Juergen Gross wrote:
> Commit 0881ace292b662 ("mm/mremap: use pmd/pud_poplulate to update page
> table entries") introduced a regression when running as Xen PV guest.
The description of that change starts with "pmd/pud_populate is the
right interface to be used to set the respective page table entries."
If this is deemed true, I don't think pmd_populate() should call
paravirt_alloc_pte(): The latter function, as its name says, is
supposed to be called for newly allocated page tables only (aiui).
> Today pmd/pud_poplulate() for Xen PV assumes that the PFN inserted is
> referencing a not yet used page table. In case of move_normal_pmd/pud()
> this is not true, resulting in WARN splats like:
I agree for the PMD part, but is including PUD here really correct?
While I don't know why that is, xen_alloc_ptpage() pins L1 tables
only. Hence a PUD update shouldn't be able to find a pinned L2
table.
Jan
next prev parent reply other threads:[~2021-09-08 11:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-08 7:36 [PATCH] xen: fix usage of pmd/pud_poplulate in mremap for pv guests Juergen Gross
2021-09-08 11:07 ` Jan Beulich [this message]
2021-09-08 13:32 ` Juergen Gross
2021-09-08 14:28 ` Jan Beulich
2021-09-08 14:47 ` Juergen Gross
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=5a4859db-d173-88dd-5ea9-dd5fd893d934@suse.com \
--to=jbeulich@suse.com \
--cc=boris.ostrovsky@oracle.com \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=jgross@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@eikelenboom.it \
--cc=mingo@redhat.com \
--cc=sstabellini@kernel.org \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=xen-devel@lists.xenproject.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