From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4C05720C012; Wed, 25 Feb 2026 01:36:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771983377; cv=none; b=moM4Aftn0+5oXBBE0I3PQowbJmo0qipKTXOOj5yc/Ok8o8I5WP7B+gVq13ZXa8iHGmto9lTMvcuUN/ms0FzTt7a+PacZ0SNKx2EEgvn65//wJUopocHZarwMAKjHyLlSHaVenfI4f+Wpc+5ppMgFADGrVYoO2zLwVHdB814ntTk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771983377; c=relaxed/simple; bh=FatDsmeB12Z23jWDrGfOVfTiK3/9HwYNOOu5Xr08wTw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EpTbg2YC/V5eUGd+99HGalmtjikBzpaYcjsLU6fpVEKrN8o+rpPJNXCf7m3GGieJqv8zQWLChvLioXpnISc/IWY5pT3nnVYkohUQtUuWMItbHY76g3G/hSkl0KPt6ML4zWqMLrRcYXGJIsj+u7Qwm2sRYy0h9MHDr1vHxGr+Bco= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=veeJdnpv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="veeJdnpv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24AFDC116D0; Wed, 25 Feb 2026 01:36:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1771983377; bh=FatDsmeB12Z23jWDrGfOVfTiK3/9HwYNOOu5Xr08wTw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=veeJdnpvHeKh0H1+eX+8tP/so5CSW/QxKHGJOYxcZGF+tkQumPR7H/+VcH98al7It bzHBGLoZ7eWvEvDeHWyxl1ATP8d7DACvcHAJINd179k5qpP0uYJX4rVM0pDyQ+KaL+ jYNO5nHObxZiINplXmLmUswOQ42Y7P4G4opGCD68= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Li Chen , Pankaj Gupta , "Michael S. Tsirkin" , Ira Weiny , Sasha Levin Subject: [PATCH 6.19 501/781] nvdimm: virtio_pmem: serialize flush requests Date: Tue, 24 Feb 2026 17:20:10 -0800 Message-ID: <20260225012412.093837228@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260225012359.695468795@linuxfoundation.org> References: <20260225012359.695468795@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Li Chen [ Upstream commit a9ba6733c7f1096c4506bf4e34a546e07242df74 ] Under heavy concurrent flush traffic, virtio-pmem can overflow its request virtqueue (req_vq): virtqueue_add_sgs() starts returning -ENOSPC and the driver logs "no free slots in the virtqueue". Shortly after that the device enters VIRTIO_CONFIG_S_NEEDS_RESET and flush requests fail with "virtio pmem device needs a reset". Serialize virtio_pmem_flush() with a per-device mutex so only one flush request is in-flight at a time. This prevents req_vq descriptor overflow under high concurrency. Reproducer (guest with virtio-pmem): - mkfs.ext4 -F /dev/pmem0 - mount -t ext4 -o dax,noatime /dev/pmem0 /mnt/bench - fio: ioengine=io_uring rw=randwrite bs=4k iodepth=64 numjobs=64 direct=1 fsync=1 runtime=30s time_based=1 - dmesg: "no free slots in the virtqueue" "virtio pmem device needs a reset" Fixes: 6e84200c0a29 ("virtio-pmem: Add virtio pmem driver") Signed-off-by: Li Chen Acked-by: Pankaj Gupta Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20260203021353.121091-1-me@linux.beauty Signed-off-by: Ira Weiny Signed-off-by: Sasha Levin --- drivers/nvdimm/nd_virtio.c | 3 ++- drivers/nvdimm/virtio_pmem.c | 1 + drivers/nvdimm/virtio_pmem.h | 4 ++++ 3 files changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c index c3f07be4aa22a..af82385be7c6a 100644 --- a/drivers/nvdimm/nd_virtio.c +++ b/drivers/nvdimm/nd_virtio.c @@ -44,6 +44,8 @@ static int virtio_pmem_flush(struct nd_region *nd_region) unsigned long flags; int err, err1; + guard(mutex)(&vpmem->flush_lock); + /* * Don't bother to submit the request to the device if the device is * not activated. @@ -53,7 +55,6 @@ static int virtio_pmem_flush(struct nd_region *nd_region) return -EIO; } - might_sleep(); req_data = kmalloc(sizeof(*req_data), GFP_KERNEL); if (!req_data) return -ENOMEM; diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c index 2396d19ce5496..77b1966619059 100644 --- a/drivers/nvdimm/virtio_pmem.c +++ b/drivers/nvdimm/virtio_pmem.c @@ -64,6 +64,7 @@ static int virtio_pmem_probe(struct virtio_device *vdev) goto out_err; } + mutex_init(&vpmem->flush_lock); vpmem->vdev = vdev; vdev->priv = vpmem; err = init_vq(vpmem); diff --git a/drivers/nvdimm/virtio_pmem.h b/drivers/nvdimm/virtio_pmem.h index 0dddefe594c46..f72cf17f9518f 100644 --- a/drivers/nvdimm/virtio_pmem.h +++ b/drivers/nvdimm/virtio_pmem.h @@ -13,6 +13,7 @@ #include #include #include +#include #include struct virtio_pmem_request { @@ -35,6 +36,9 @@ struct virtio_pmem { /* Virtio pmem request queue */ struct virtqueue *req_vq; + /* Serialize flush requests to the device. */ + struct mutex flush_lock; + /* nvdimm bus registers virtio pmem device */ struct nvdimm_bus *nvdimm_bus; struct nvdimm_bus_descriptor nd_desc; -- 2.51.0