From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Xu <peterx@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>,
QEMU Devel Mailing List <qemu-devel@nongnu.org>
Subject: Re: Question on memory commit during MR finalize()
Date: Mon, 20 Apr 2020 23:44:11 +0200 [thread overview]
Message-ID: <fe73a74b-2324-68a5-a37f-530a6bb03ebc@redhat.com> (raw)
In-Reply-To: <20200420210049.GA420399@xz-x1>
On 20/04/20 23:00, Peter Xu wrote:
>
> I'm still uncertain how the dirty ring branch can easily trigger this, however
> the backtrace looks really odd to me in that we're going to do memory commit
> and even sending KVM ioctls during finalize(), especially in the RCU thread...
> I never expected that.
Short answer: it is really hard to not trigger finalize() from an RCU
callback, and it's the reason why the RCU thread takes the big QEMU lock.
However, instead of memory_region_transaction_commit,
memory_region_finalize probably should do something like
--memory_region_transaction_depth;
assert (memory_region_transaction_depth ||
(!memory_region_update_pending &&
!ioeventfd_update_pending));
Paolo
next prev parent reply other threads:[~2020-04-20 21:44 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-20 21:00 Question on memory commit during MR finalize() Peter Xu
2020-04-20 21:44 ` Paolo Bonzini [this message]
2020-04-20 23:31 ` Peter Xu
2020-04-21 9:43 ` Paolo Bonzini
2020-04-21 10:43 ` Peter Xu
2021-07-15 14:27 ` Thanos Makatos
2021-07-15 18:35 ` Peter Xu
2021-07-16 11:42 ` Thanos Makatos
2021-07-16 14:18 ` Peter Xu
2021-07-19 14:38 ` Thanos Makatos
2021-07-19 15:56 ` Peter Xu
2021-07-19 18:02 ` Thanos Makatos
2021-07-19 19:05 ` Thanos Makatos
2021-07-19 19:59 ` Peter Xu
2021-07-19 20:58 ` John Johnson
2021-07-20 1:22 ` Peter Xu
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=fe73a74b-2324-68a5-a37f-530a6bb03ebc@redhat.com \
--to=pbonzini@redhat.com \
--cc=armbru@redhat.com \
--cc=peterx@redhat.com \
--cc=qemu-devel@nongnu.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).