From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (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 3031B1AD272; Tue, 3 Sep 2024 09:34:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725356055; cv=none; b=QM7x6S7nfBvLizSZdLVlYq5/rS9dpPF+4ubaVDRYPnR9asiLMqBdO/RPZrn6X2yevoZCYnxe8QBsZanD+1EoGRpIBCJAzjWkEn44ooVrKjfb4DRmCKnC/gnDyo9EcdC0LwsqSCltJPw38Pm4CLIuEkjlnFYhUfPFqS8zj7/W87o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725356055; c=relaxed/simple; bh=7jJBly8Y6bE9sPKCf9EEsc7epwehNU1txM4jSXiORyI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PI4dPKP9OgTv0dWOk8aaiDjehRBp7HSsu01vlZlSjCzq0aXJJtYlW6G8Nsza8lzkwfOhsy+N5lbSFQTuM6dAxPflwVGyt0kqfhRy56mSk2Z5WWb1m35psVqZZXMnM9YLKJnOUdKZu3guvg1N2HrdNn0giabNiTDmON3ahdHgI98= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=o5t/zlcD; arc=none smtp.client-ip=115.124.30.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="o5t/zlcD" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1725356045; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=Eb+P3ApRDSOdltbSEo0YbmmjQpT9J2C1awOD4TBbcTc=; b=o5t/zlcDDQiluvCQpsgwrWnl05SGXVPXxITmWO3hiCL5O1GWmn2mzHyOmGbV0pPujhjqGtPl0YUum01UnoV+VT6EjBM4xiZDr3PzlvoW+ngalvMz8SsKKmzKi4CSsnttPBFSYBWUEYw6mtqoyLPj7ZFdi7lq+vXqa9J673jxQHM= Received: from 30.221.113.157(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0WECwpGA_1725356043) by smtp.aliyun-inc.com; Tue, 03 Sep 2024 17:34:04 +0800 Message-ID: <5769af42-e4dd-4535-9432-f149b8c17af5@linux.alibaba.com> Date: Tue, 3 Sep 2024 17:34:01 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/2] virtiofs: use GFP_NOFS when enqueuing request through kworker To: Hou Tao , linux-fsdevel@vger.kernel.org Cc: Miklos Szeredi , Vivek Goyal , Stefan Hajnoczi , Bernd Schubert , "Michael S . Tsirkin" , Matthew Wilcox , Benjamin Coddington , linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, houtao1@huawei.com References: <20240831093750.1593871-1-houtao@huaweicloud.com> <20240831093750.1593871-3-houtao@huaweicloud.com> Content-Language: en-US From: Jingbo Xu In-Reply-To: <20240831093750.1593871-3-houtao@huaweicloud.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/31/24 5:37 PM, Hou Tao wrote: > From: Hou Tao > > When invoking virtio_fs_enqueue_req() through kworker, both the > allocation of the sg array and the bounce buffer still use GFP_ATOMIC. > Considering the size of the sg array may be greater than PAGE_SIZE, use > GFP_NOFS instead of GFP_ATOMIC to lower the possibility of memory > allocation failure and to avoid unnecessarily depleting the atomic > reserves. GFP_NOFS is not passed to virtio_fs_enqueue_req() directly, > GFP_KERNEL and memalloc_nofs_{save|restore} helpers are used instead. > > It may seem OK to pass GFP_NOFS to virtio_fs_enqueue_req() as well when > queuing the request for the first time, but this is not the case. The > reason is that fuse_request_queue_background() may call > ->queue_request_and_unlock() while holding fc->bg_lock, which is a > spin-lock. Therefore, still use GFP_ATOMIC for it. Actually, .wake_pending_and_unlock() is called under fiq->lock and GFP_ATOMIC is requisite. > > Signed-off-by: Hou Tao > --- > fs/fuse/virtio_fs.c | 24 +++++++++++++++--------- > 1 file changed, 15 insertions(+), 9 deletions(-) > > diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c > index 43d66ab5e891..9bc48b3ca384 100644 > --- a/fs/fuse/virtio_fs.c > +++ b/fs/fuse/virtio_fs.c > @@ -95,7 +95,8 @@ struct virtio_fs_req_work { > }; > > static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq, > - struct fuse_req *req, bool in_flight); > + struct fuse_req *req, bool in_flight, > + gfp_t gfp); > > static const struct constant_table dax_param_enums[] = { > {"always", FUSE_DAX_ALWAYS }, > @@ -439,6 +440,8 @@ static void virtio_fs_request_dispatch_work(struct work_struct *work) > > /* Dispatch pending requests */ > while (1) { > + unsigned int flags; > + > spin_lock(&fsvq->lock); > req = list_first_entry_or_null(&fsvq->queued_reqs, > struct fuse_req, list); > @@ -449,7 +452,9 @@ static void virtio_fs_request_dispatch_work(struct work_struct *work) > list_del_init(&req->list); > spin_unlock(&fsvq->lock); > > - ret = virtio_fs_enqueue_req(fsvq, req, true); > + flags = memalloc_nofs_save(); > + ret = virtio_fs_enqueue_req(fsvq, req, true, GFP_KERNEL); > + memalloc_nofs_restore(flags); > if (ret < 0) { > if (ret == -ENOSPC) { > spin_lock(&fsvq->lock); > @@ -550,7 +555,7 @@ static void virtio_fs_hiprio_dispatch_work(struct work_struct *work) > } > > /* Allocate and copy args into req->argbuf */ > -static int copy_args_to_argbuf(struct fuse_req *req) > +static int copy_args_to_argbuf(struct fuse_req *req, gfp_t gfp) > { > struct fuse_args *args = req->args; > unsigned int offset = 0; > @@ -564,7 +569,7 @@ static int copy_args_to_argbuf(struct fuse_req *req) > len = fuse_len_args(num_in, (struct fuse_arg *) args->in_args) + > fuse_len_args(num_out, args->out_args); > > - req->argbuf = kmalloc(len, GFP_ATOMIC); > + req->argbuf = kmalloc(len, gfp); > if (!req->argbuf) > return -ENOMEM; > > @@ -1239,7 +1244,8 @@ static unsigned int sg_init_fuse_args(struct scatterlist *sg, > > /* Add a request to a virtqueue and kick the device */ > static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq, > - struct fuse_req *req, bool in_flight) > + struct fuse_req *req, bool in_flight, > + gfp_t gfp) > { > /* requests need at least 4 elements */ > struct scatterlist *stack_sgs[6]; > @@ -1260,8 +1266,8 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq, > /* Does the sglist fit on the stack? */ > total_sgs = sg_count_fuse_req(req); > if (total_sgs > ARRAY_SIZE(stack_sgs)) { > - sgs = kmalloc_array(total_sgs, sizeof(sgs[0]), GFP_ATOMIC); > - sg = kmalloc_array(total_sgs, sizeof(sg[0]), GFP_ATOMIC); > + sgs = kmalloc_array(total_sgs, sizeof(sgs[0]), gfp); > + sg = kmalloc_array(total_sgs, sizeof(sg[0]), gfp); > if (!sgs || !sg) { > ret = -ENOMEM; > goto out; > @@ -1269,7 +1275,7 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq, > } > > /* Use a bounce buffer since stack args cannot be mapped */ > - ret = copy_args_to_argbuf(req); > + ret = copy_args_to_argbuf(req, gfp); > if (ret < 0) > goto out; > > @@ -1367,7 +1373,7 @@ __releases(fiq->lock) > queue_id); > > fsvq = &fs->vqs[queue_id]; > - ret = virtio_fs_enqueue_req(fsvq, req, false); > + ret = virtio_fs_enqueue_req(fsvq, req, false, GFP_ATOMIC); > if (ret < 0) { > if (ret == -ENOSPC) { > /* LGTM. Reviewed-by: Jingbo Xu -- Thanks, Jingbo