Re: [PATCH] reserved buffers only for PF_MEMALLOC

[Marcelo Tosatti]

On Tue, Aug 10, 2004 at 01:20:24PM -0400, Rik van Riel wrote:
> 
> The buffer allocation path in 2.4 has a long standing bug,
> where non-PF_MEMALLOC tasks can dig into the reserved pool
> in get_unused_buffer_head().  The following patch makes the
> reserved pool only accessible to PF_MEMALLOC tasks.
> 
> Other processes will loop in create_buffers() - the only
> function that calls get_unused_buffer_head() - and will call
> try_to_free_pages(GFP_NOIO), freeing any buffer heads that
> have become freeable due to IO completion.
> 
> Note that PF_MEMALLOC tasks will NOT do anything inside
> try_to_free_pages(), so it is needed that they are able to
> dig into the reserved buffer heads while other tasks are
> not.

Applied.

Matt, it would be really nice if you could run the workload
which triggers the deadlock on 2.4.27+Rik's patch.

Thanks guys!
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