linux-kernel - Re: [PATCH 0/4] Fix type confusion in page_table

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Message-ID: <ZF0KcRgclDJ6POrb@infradead.org>
Date:   Thu, 11 May 2023 08:32:01 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Ruihan Li <lrh2000@....edu.cn>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-mm@...ck.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Pasha Tatashin <pasha.tatashin@...een.com>,
        David Hildenbrand <david@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH 0/4] Fix type confusion in page_table_check

On Thu, May 11, 2023 at 09:44:55PM +0800, Ruihan Li wrote:
> Christoph's patch perfectly fixes _one_ problem: kmalloc'ed memory
> cannot be mapped to user space. However, as I detailed in the commit
> message, this series of patches fixes _three_ problems.

FYI, I agree with you.  My simple patch was sent before reading
your new series, and is a strict subset of it.

> I have to say that the original code is quite buggy. In the
> gen_pool_dma_alloc path, there is no guarantee of page alignment. 

I also find this whole interface very problematic to start with,
but that's a separate discussion for later.