linux-kernel - Re: [PATCH 4/5] mm: soft-dirty bits for user memory changes tracking

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Date:	Fri, 03 May 2013 23:09:04 +0400
From:	Pavel Emelyanov <xemul@...allels.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Glauber Costa <glommer@...allels.com>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Matt Mackall <mpm@...enic.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux MM <linux-mm@...ck.org>
Subject: Re: [PATCH 4/5] mm: soft-dirty bits for user memory changes tracking

On 05/03/2013 03:36 PM, Xiao Guangrong wrote:
> On 05/01/2013 12:12 AM, Pavel Emelyanov wrote:
> 
>> +static inline void clear_soft_dirty(struct vm_area_struct *vma,
>> +		unsigned long addr, pte_t *pte)
>> +{
>> +#ifdef CONFIG_MEM_SOFT_DIRTY
>> +	/*
>> +	 * The soft-dirty tracker uses #PF-s to catch writes
>> +	 * to pages, so write-protect the pte as well. See the
>> +	 * Documentation/vm/soft-dirty.txt for full description
>> +	 * of how soft-dirty works.
>> +	 */
>> +	pte_t ptent = *pte;
>> +	ptent = pte_wrprotect(ptent);
>> +	ptent = pte_clear_flags(ptent, _PAGE_SOFT_DIRTY);
>> +	set_pte_at(vma->vm_mm, addr, pte, ptent);
>> +#endif
> 
> It seems that TLBs are not flushed and mmu-notification is not called?

TLBs are flushed by clear_refs_write()->flush_tlb_mm().

As far as MMU notification is concerned -- yes, you're right! I will
prepare the patch for this soon.

> .
> 


Thanks,
Pavel
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