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From: Benjamin Coddington <bcodding@redhat.com>
To: Hou Tao <houtao@huaweicloud.com>
Cc: linux-fsdevel@vger.kernel.org, Miklos Szeredi <miklos@szeredi.hu>,
 Vivek Goyal <vgoyal@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>,
 Matthew Wilcox <willy@infradead.org>, linux-kernel@vger.kernel.org,
 virtualization@lists.linux.dev, houtao1@huawei.com
Subject: Re: [PATCH v2] virtiofs: use GFP_NOFS when enqueuing request through
 kworker
Date: Mon, 08 Jan 2024 10:48:24 -0500
Message-ID: <A7DF37C3-9C00-4C3C-BFD3-12BE0DE699B3@redhat.com>
In-Reply-To: <20240105105305.4052672-1-houtao@huaweicloud.com>
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On 5 Jan 2024, at 5:53, Hou Tao wrote:

> From: Hou Tao <houtao1@huawei.com>
>
> 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 both the sg array and the bounce buffer may be
> greater than PAGE_SIZE, use GFP_NOFS instead of GFP_ATOMIC to lower the
> possibility of memory allocation failure.

Perhaps not appropriate for this case, but are you aware of
memalloc_nofs_save/restore?  NFS has been converting over and cleaning out
our GFP_NOFS usage:

Documentation/core-api/gfp_mask-from-fs-io.rst

Ben