From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] x86/vmemmap: Drop handling of 1GB vmemmap ranges
Date: Wed, 3 Feb 2021 15:15:58 +0100 [thread overview]
Message-ID: <20210203141553.GA26770@linux> (raw)
In-Reply-To: <a503f51d-42fe-3cd1-aa7c-66af33f1b3f8@redhat.com>
On Wed, Feb 03, 2021 at 03:12:05PM +0100, David Hildenbrand wrote:
> On 03.02.21 15:10, Oscar Salvador wrote:
> > On Wed, Feb 03, 2021 at 02:33:56PM +0100, David Hildenbrand wrote:
> > > One problem I see with existing code / this change making more obvious is
> > > that when trying to remove in other granularity than we added (e.g., unplug
> > > a 128MB DIMM avaialble during boot), we remove the direct map of unrelated
> > > DIMMs.
> >
> > So, let me see if I understand your concern.
> >
> > We have a range that was mapped with 1GB page, and we try to remove
> > a 128MB chunk from it.
> > Yes, in that case we would clear the pud, and that is bad, so we should
> > keep the PAGE_ALIGNED checks.
> >
> > Now, let us assume that scenario.
> > If you have a 1GB mapped range and you remove it in smaller chunks bit by bit
> > (e.g: 128M), the direct mapping of that range will never be cleared unless
>
> No, that's exactly what's happening. Good thing is that it barely ever
> happens, so I assume leaving behind some direct mapping / page tables is not
> that bad.
Sorry, I meant that that is the current situation now.
Then let us keep the PAGE_ALIGNED stuff.
I shall resend a v3 later today.
thanks for the review ;-)
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-02-03 14:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 10:47 [PATCH v2 0/3] Cleanup and fixups for vmemmap handling Oscar Salvador
2021-02-03 10:47 ` [PATCH v2 1/3] x86/vmemmap: Drop handling of 4K unaligned vmemmap range Oscar Salvador
2021-02-03 13:29 ` David Hildenbrand
2021-02-11 21:25 ` Oscar Salvador
2021-02-03 10:47 ` [PATCH v2 2/3] x86/vmemmap: Drop handling of 1GB vmemmap ranges Oscar Salvador
2021-02-03 13:33 ` David Hildenbrand
2021-02-03 14:10 ` Oscar Salvador
2021-02-03 14:12 ` David Hildenbrand
2021-02-03 14:15 ` Oscar Salvador [this message]
2021-02-03 10:47 ` [PATCH v2 3/3] x86/vmemmap: Handle unpopulated sub-pmd ranges Oscar Salvador
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=20210203141553.GA26770@linux \
--to=osalvador@suse.de \
--cc=akpm@linux-foundation.org \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=david@redhat.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=mhocko@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.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).