From: Sean Christopherson <seanjc@google.com>
To: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Michal Hocko <mhocko@suse.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: Fix rmap allocation for very large memslots
Date: Fri, 28 Jan 2022 21:47:54 +0000 [thread overview]
Message-ID: <YfRkivAI2P6urdfn@google.com> (raw)
In-Reply-To: <1acaee7fa7ef7ab91e51f4417572b099caf2f400.1643405658.git.maciej.szmigiero@oracle.com>
On Fri, Jan 28, 2022, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
>
> Commit 7661809d493b ("mm: don't allow oversized kvmalloc() calls") has
> forbidden using kvmalloc() to make allocations larger than INT_MAX (2 GiB).
>
> Unfortunately, adding a memslot exceeding 1 TiB in size will result in rmap
> code trying to make an allocation exceeding this limit.
> Besides failing this allocation, such operation will also trigger a
> WARN_ON_ONCE() added by the aforementioned commit.
>
> Since we probably still want to use kernel slab for small rmap allocations
> let's only redirect such oversized allocations to vmalloc.
>
> A possible alternative would be to add some kind of a __GFP_LARGE flag to
> skip the INT_MAX check behind kvmalloc(), however this will impact the
> common kernel memory allocation code, not just KVM.
Paolo has a cleaner fix for this[1][2], but it appears to have stalled out somewhere.
Paolo???
[1] https://lore.kernel.org/all/20211015165519.135670-1-pbonzini@redhat.com
[2] https://lore.kernel.org/all/20211016064302.165220-1-pbonzini@redhat.com
next prev parent reply other threads:[~2022-01-28 21:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-28 21:36 [PATCH] KVM: x86: Fix rmap allocation for very large memslots Maciej S. Szmigiero
2022-01-28 21:47 ` Sean Christopherson [this message]
2022-02-10 21:00 ` Maciej S. Szmigiero
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=YfRkivAI2P6urdfn@google.com \
--to=seanjc@google.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mail@maciej.szmigiero.name \
--cc=mhocko@suse.com \
--cc=pbonzini@redhat.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.