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

From: Christoph Hellwig
Date: Tue Sep 01 2020 - 13:16:57 EST


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@xxxxxx>