linux-kernel - Re: [PATCH v2 1/6] fuse: limit the length of ITER_KVEC dio by max

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Message-ID: <CAJfpegtMhkKG-Hk5vQ5gi6bSqwb=eMG9_TzcW7b08AtXBmnQXQ@mail.gmail.com>
Date: Fri, 1 Mar 2024 14:42:14 +0100
From: Miklos Szeredi <miklos@...redi.hu>
To: Hou Tao <houtao@...weicloud.com>
Cc: linux-fsdevel@...r.kernel.org, Vivek Goyal <vgoyal@...hat.com>, 
	Stefan Hajnoczi <stefanha@...hat.com>, Bernd Schubert <bernd.schubert@...tmail.fm>, 
	"Michael S . Tsirkin" <mst@...hat.com>, Matthew Wilcox <willy@...radead.org>, 
	Benjamin Coddington <bcodding@...hat.com>, linux-kernel@...r.kernel.org, 
	virtualization@...ts.linux.dev, houtao1@...wei.com
Subject: Re: [PATCH v2 1/6] fuse: limit the length of ITER_KVEC dio by max_pages

On Wed, 28 Feb 2024 at 15:40, Hou Tao <houtao@...weicloud.com> wrote:

> So instead of limiting both the values of max_read and max_write in
> kernel, capping the maximal length of kvec iter IO by using max_pages in
> fuse_direct_io() just like it does for ubuf/iovec iter IO. Now the max
> value for max_pages is 256, so on host with 4KB page size, the maximal
> size passed to kmalloc() in copy_args_to_argbuf() is about 1MB+40B. The
> allocation of 2MB of physically contiguous memory will still incur
> significant stress on the memory subsystem, but the warning is fixed.
> Additionally, the requirement for huge physically contiguous memory will
> be removed in the following patch.

So the issue will be fixed properly by following patches?

In that case this patch could be omitted, right?

Thanks,
Miklos