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Thu, 13 Nov 2025 13:04:58 -0800 (PST) Received: from x1.local ([142.188.210.50]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4ede887cb42sm18280781cf.36.2025.11.13.13.04.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Nov 2025 13:04:57 -0800 (PST) Date: Thu, 13 Nov 2025 16:04:54 -0500 From: Peter Xu To: Matthew Rosato Cc: Peter Maydell , qemu-devel@nongnu.org, Fabiano Rosas , David Hildenbrand , Paolo Bonzini , Steve Sistare , Alex Williamson , Cedric Le Goater Subject: Re: [PULL 37/45] migration: multi-mode notifier Message-ID: References: <20251003153948.1304776-1-peterx@redhat.com> <20251003153948.1304776-38-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Nov 13, 2025 at 03:28:12PM -0500, Matthew Rosato wrote: > On 10/3/25 11:39 AM, Peter Xu wrote: > > From: Steve Sistare > > > > Allow a notifier to be added for multiple migration modes. > > To allow a notifier to appear on multiple per-node lists, use > > a generic list type. We can no longer use NotifierWithReturnList, > > because it shoe horns the notifier onto a single list. > > > > Signed-off-by: Steve Sistare > > Reviewed-by: Fabiano Rosas > > Link: https://lore.kernel.org/r/1759332851-370353-2-git-send-email-steven.sistare@oracle.com > > Signed-off-by: Peter Xu > > ... > > > void migration_remove_notifier(NotifierWithReturn *notify) > > { > > if (notify->notify) { > > - notifier_with_return_remove(notify); > > + for (MigMode mode = 0; mode < MIG_MODE__MAX; mode++) { > > + migration_blockers[mode] = > > + g_slist_remove(migration_state_notifiers[mode], notify); > > + } > > notify->notify = NULL; > > } > > Hi, we started noticing occasional crashes on detach of vfio-pci devices on s390x. > > The pattern we used to reliably hit the issue is to attach/detach the same hostdev to a guest; crash usually happens on the second detach, sometimes the third. > > I did a bisect and it points to this patch. This code isn't my area of expertise, but the change above looks wrong. > > I tried the following diff and it resolves the crash for me at least: > > diff --git a/migration/migration.c b/migration/migration.c > index c2daab6bdd..9e787749b2 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -1693,7 +1693,7 @@ void migration_remove_notifier(NotifierWithReturn *notify) > { > if (notify->notify) { > for (MigMode mode = 0; mode < MIG_MODE__MAX; mode++) { > - migration_blockers[mode] = > + migration_state_notifiers[mode] = > g_slist_remove(migration_state_notifiers[mode], notify); > } > notify->notify = NULL; I bet you're correct, thanks for reporting and providing the fix. Could you prepare a formal patch and send it to the list? I can collect it for the rc pull. Thanks, -- Peter Xu