linux-kernel - Re: [PATCH UPDATE] x86: ignore spurious faults

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Message-ID: <4798E51C.4000209@goop.org>
Date:	Thu, 24 Jan 2008 11:21:00 -0800
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Matt Mackall <mpm@...enic.com>
CC:	Harvey Harrison <harvey.harrison@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andi Kleen <ak@...e.de>
Subject: Re: [PATCH UPDATE] x86: ignore spurious faults

Matt Mackall wrote:
> There's perhaps an opportunity to do this lazy TLB trick in the mmap
> path as well, where RW mappings are initially mapped as RO so we can
> catch processes dirtying them and then switched to RW. If the mapping is
> shared across threads on multiple cores, we can defer synchronizing the
> TLBs on the others.
>   

I think spurious usermode faults are already dealt with.  
handle_pte_fault() does essentially the same thing as this patch:

	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
		update_mmu_cache(vma, address, entry);
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}



    J
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