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Mon, 02 Nov 2026 12:35:22 -0800 (PST) Received: from i4-gl-tmk5904.ad.psu.edu ([130.203.156.186]) by smtp.gmail.com with ESMTPSA id af79cd13be357-944252e5162sm916242185a.5.2026.11.02.12.35.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Nov 2026 12:35:21 -0800 (PST) From: Yuho Choi To: David Hildenbrand , "Michael S. Tsirkin" Cc: Jason Wang , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Xuan Zhuo , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, Yuho Choi Subject: [PATCH v2] virtio-mem: only mark the device ready in kdump mode with vmcore support Date: Mon, 2 Nov 2026 15:35:16 -0500 Message-ID: <20261102203518.436327-2-oss.patchbox@gmail.com> X-Mailer: git-send-email 2.43.0 X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit virtio_mem_init_kdump() marks the device DRIVER_OK before it checks for CONFIG_PROC_VMCORE. Without vmcore support it then fails with -EBUSY, and virtio_mem_probe() deletes the virtqueue on that error path without resetting the device first. The device is left with DRIVER_OK set and a queue that points at freed memory. Nothing has been queued at that point, so the device has nothing to process, but the driver should not leave a device it is giving up on marked ready. Before commit a9403425b3cf ("virtio-mem: mark device ready before registering callbacks in kdump mode"), virtio_mem_probe() called virtio_device_ready() only after virtio_mem_init() had succeeded, so this path never exposed a ready device. Move virtio_device_ready() into the CONFIG_PROC_VMCORE branch, right before the vmcore callbacks that need it are registered, so the -EBUSY path never sets DRIVER_OK. Fixes: a9403425b3cf ("virtio-mem: mark device ready before registering callbacks in kdump mode") Signed-off-by: Yuho Choi --- v2: - Drop Cc: stable, as no practical kdump kernel disables PROC_VMCORE (David). - Say in the changelog that nothing is queued on this path. - Rebased on v7.4-rc1. v1: https://lore.kernel.org/r/20261016023521.747447-1-oss.patchbox@gmail.com Compile-tested with W=1, with and without CONFIG_PROC_VMCORE. drivers/virtio/virtio_mem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index e18dd736f2ec..b28d2da7d5b6 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -2817,9 +2817,9 @@ static int virtio_mem_vmcore_get_device_ram(struct vmcore_cb *cb, static int virtio_mem_init_kdump(struct virtio_mem *vm) { +#ifdef CONFIG_PROC_VMCORE /* We must be prepared to receive a callback immediately. */ virtio_device_ready(vm->vdev); -#ifdef CONFIG_PROC_VMCORE dev_info(&vm->vdev->dev, "memory hot(un)plug disabled in kdump kernel\n"); vm->vmcore_cb.pfn_is_ram = virtio_mem_vmcore_pfn_is_ram; #ifdef CONFIG_PROC_VMCORE_DEVICE_RAM -- 2.43.0