linux-kernel - Re: [PATCH v3 1/3] kernfs: remove page_mkwrite() from vm_operations

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Message-ID: <310071c8-04b7-4996-a496-614c2bdb8163@eideticom.com>
Date: Thu, 4 Jul 2024 14:43:04 -0600
From: Martin Oliveira <martin.oliveira@...eticom.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 linux-rdma@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
 Artemy Kovalyov <artemyko@...dia.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
 Logan Gunthorpe <logang@...tatee.com>,
 Michael Guralnik <michaelgur@...dia.com>,
 Mike Marciniszyn <mike.marciniszyn@...el.com>, Tejun Heo <tj@...nel.org>,
 John Hubbard <jhubbard@...dia.com>, Dan Williams <dan.j.williams@...el.com>,
 David Sloan <david.sloan@...eticom.com>
Subject: Re: [PATCH v3 1/3] kernfs: remove page_mkwrite() from
 vm_operations_struct

On 2024-07-04 11:02, Matthew Wilcox wrote:> Seems to me we should actually _handle_ that, not do something wrong.
> eg:
> 
>         if (vma->vm_ops) {
>                 if (vma->vm_ops->close)
>                         goto out_put;
>                 if (WARN_ON(vma->vm_ops->page_mkwrite))
>                         goto out_put;
>         }

Good point.

> or maybe this doesn't need to be a WARN at all?  After all, there
> isn't one for having a ->close method, so why is page_mkwrite special?

Hmm yeah, they should probably be treated the same.

Maybe ->close should be converted to WARN as well? It would be easier to
catch an error this way than chasing the EINVAL, but I'm OK either way.

Thanks,
Martin