linux-kernel - Re: [PATCH 1/6] proc: use vmalloc for our kernel buffer

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Message-ID: <20200901151420.GA30709@lst.de>
Date:   Tue, 1 Sep 2020 17:14:20 +0200
From:   Christoph Hellwig <hch@....de>
To:     Josef Bacik <josef@...icpanda.com>
Cc:     hch@....de, viro@...IV.linux.org.uk, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, willy@...radead.org,
        kernel-team@...com
Subject: Re: [PATCH 1/6] proc: use vmalloc for our kernel buffer

On Thu, Aug 13, 2020 at 05:04:06PM -0400, Josef Bacik wrote:
> Since
> 
>   sysctl: pass kernel pointers to ->proc_handler
> 
> we have been pre-allocating a buffer to copy the data from the proc
> handlers into, and then copying that to userspace.  The problem is this
> just blind kmalloc()'s the buffer size passed in from the read, which in
> the case of our 'cat' binary was 64kib.  Order-4 allocations are not
> awesome, and since we can potentially allocate up to our maximum order,
> use vmalloc for these buffers.

Maybe the subject should read ".. also use vmalloc" as we still default
to kmalloc for small allocations?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@....de>