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Tsirkin" To: "David Hildenbrand (Arm)" Cc: linux-kernel@vger.kernel.org, Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Adam Litke , Rusty Russell , virtualization@lists.linux.dev, Andrew Morton , linux-mm@kvack.org Subject: Re: [PATCH v2] virtio_balloon: prime stats vq after virtio_device_ready() Message-ID: <20260706044122-mutt-send-email-mst@kernel.org> References: <2f0d0de033f3005d3b985883be3e5cf37b3f6c42.1783278596.git.mst@redhat.com> <13794c5e-375a-4fc5-84b4-a637d077f8a0@kernel.org> <20260706042207-mutt-send-email-mst@kernel.org> <6b8e4ad3-6909-4d0a-89a4-104a5ad9fe79@kernel.org> MIME-Version: 1.0 In-Reply-To: <6b8e4ad3-6909-4d0a-89a4-104a5ad9fe79@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: EGD-mW2GNZPTVZmsxfg5tu221mFFoYN4HwdO0tX4MJM_1783327443 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 299B91C0002 X-Stat-Signature: j6yqotprct5g8faagxrrzkuxmuxjtweq X-HE-Tag: 1783327445-656508 X-HE-Meta: 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 jaGiXjrf N3uHMVCh5mrJXfUGzQv5q2weoxsyZ9sGaKPDXY8h+g3nWNgFrICkIf2+048YAGQfIVeR+Yfn4K3FQ5U6HKd8ZH4o3n7LOktcPatgNDUH1IkTcSbUDggc18+Jjc4tDD6LrRzV14R6oPYQZdFd8gd+qACHKUhWu4/7NmePu16ywApFTHfk1NeB7SZoTovGCDs2Uzq4ViFWVbL4PW1mlgr0F0fIeTrAHPbPsdmvGONUJUErJnJgimdNvlaA3R0wzek4VZvUFrv6wD0qJJnVVSWgBiXU+LRtAtEyBiomEwKWCwXFoUwNTIL54SpwzIzoSWg16TSBZ13FGzkWijdtmLCy9FDOsFj8uPzyf9FKDl0MJGaLKMl5JTDm27NUKXYzByRfnyFNl Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 06, 2026 at 10:38:18AM +0200, David Hildenbrand (Arm) wrote: > >>> - virtqueue_kick(vb->stats_vq); > >>> + disable_work(&vb->update_balloon_stats_work); > >> > >> That's to stop the stats queue triggering stats_request() I assume? > > > > Yes. > > > >> Is that > >> valid before we actually added+kicked ourselves? > > > > Why not? > > I was wondering whether the spec would state something about that. Sorry I do not get the question. Virtio API expects callers to serialize calls for each VQ. So this just prevents the work from running and accessing the VQ while probe calls add_buf/kick. I'll add a comment explaining that. But it has nothing to do with the spec. > > > >> Also, can't we simply handle that in stats_request(), just ignoring it there? > > > > Then we'd need to maintain a special flag and I dislike that. > > I was hoping that we could use the device-ready indication, but there would be a > small race window indeed. > > -- > Cheers, > > David