Re: [PATCH v2] virtiofs: use GFP_NOFS when enqueuing request through kworker

[Matthew Wilcox]

On Fri, Jan 05, 2024 at 03:17:19PM -0500, Vivek Goyal wrote:
> On Fri, Jan 05, 2024 at 06:53:05PM +0800, Hou Tao wrote:
> > From: Hou Tao <houtao1@xxxxxxxxxx>
> > 
> > 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.
> > 
> 
> What's the practical benefit of this patch. Looks like if memory
> allocation fails, we keep retrying at interval of 1ms and don't
> return error to user space.

You don't deplete the atomic reserves unnecessarily?