linux-kernel - Re: [RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking of dirty & young

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Date:	Wed, 20 Jul 2011 07:39:40 -0700
From:	Darren Hart <darren.hart@...el.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	Shan Hai <haishan.bai@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>, paulus@...ba.org,
	tglx@...utronix.de, walken@...gle.com, dhowells@...hat.com,
	cmetcalf@...era.com, tony.luck@...el.com,
	akpm@...ux-foundation.org, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking
 of dirty & young

Obviously no objection from the futex side of things, looks good. Couple
nits on the function comment:

On 07/18/2011 09:29 PM, Benjamin Herrenschmidt wrote:
...
> -/**
> +/*
> + * fixup_user_fault() - manually resolve a user page  fault

s/  fault/ fault/

> + * @tsk:	the task_struct to use for page fault accounting, or
> + *		NULL if faults are not to be recorded.
> + * @mm:		mm_struct of target mm
> + * @address:	user address
> + * @fault_flags:flags to pass down to handle_mm_fault()
> + *
> + * This is meant to be called in the specific scenario where for
> + * locking reasons we try to access user memory in atomic context
> + * (within a pagefault_disable() section), this returns -EFAULT,
> + * and we want to resolve the user fault before trying again.
> + *
> + * Typically this is meant to be used by the futex code.
> + *
> + * The main difference with get_user_pages() is that this function
> + * will unconditionally call handle_mm_fault() which will in turn
> + * perform all the necessary SW fixup of the dirty and young bits
> + * in the PTE, while handle_mm_fault() only guarantees to update
> + * these in the struct page.
> + *
> + * This is important for some architectures where those bits also
> + * gate the access permission to the page because their are

s/their/they/

Thanks,

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel
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