Messages in this thread | | | Date | Tue, 27 Dec 2011 13:58:36 -0800 | From | Andrew Morton <> | Subject | Re: [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock |
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On Tue, 27 Dec 2011 13:44:21 -0800 Tejun Heo <tj@kernel.org> wrote:
> I'm not convinced trying to put this into GFP_KERNEL context would > work. Short of that, the next best thing would be making percpu > allocator useable from memory reclaim path, right?
Well.. All allocations which are weaker than GFP_KERNEL are to be discouraged. That being said...
> But that would > involved a lot more churn and complexity without much added benefit, > given that this type of use cases aren't expected to be common - and > I'm fairly sure it isn't given track record of past few years.
I don't think it would be too hard to add an alloc_percpu_gfp(). Add the gfp_t to a small number of functions (two or three?) then change pcpu_mem_zalloc() to always use kzalloc() if (flags & GFP_KERNEL != GFP_KERNEL). And that's it?
But the question is: is this a *good* thing to do? It would be nice if kernel developers understood that GFP_KERNEL is strongly preferred and that they should put in effort to use it. But there's a strong tendency for people to get themselves into a sticky corner then take the easy way out, resulting in less robust code. Maybe calling the function alloc_percpu_i_really_suck() would convey the hint.
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