From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: William Lee Irwin III <wli@holomorphy.com>,
Andi Kleen <ak@suse.de>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
Nick Piggin <nickpiggin@yahoo.com.au>,
"H. Peter Anvin" <hpa@zytor.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Why preallocate pmd in x86 32-bit PAE?
Date: Fri, 16 Nov 2007 11:43:43 -0800 [thread overview]
Message-ID: <473DF2EF.70404@goop.org> (raw)
In-Reply-To: <alpine.LFD.0.9999.0711161118160.4260@woody.linux-foundation.org>
Linus Torvalds wrote:
> On Fri, 16 Nov 2007, Jeremy Fitzhardinge wrote:
>
>> If you happened to do a 1G munmap, it may end up freeing and
>> reallocating them, but that's going to be very rare.
>>
>
> I don't think we ever free the pmd's now, do we?
>
> (Except for the *final* free, of course, when we release the whole VM).
Not for 32-bit at the moment, but it does in principle. munmap ends up
calling free_pgtables, and so ends up calling pmd_free_range. That will
do a pud_clear to detach the pmd from the pagetable and call
__pmd_free_tlb, which ends up doing tlb_remove_page ->
free_page_and_swap_cache. 32-bit knobbles all this at the moment, but
it looks to me like it wouldn't be hard to make this work if the code is
all common with 64-bit.
J
next prev parent reply other threads:[~2007-11-16 19:44 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-15 21:57 Why preallocate pmd in x86 32-bit PAE? Jeremy Fitzhardinge
2007-11-15 22:12 ` Linus Torvalds
2007-11-15 22:42 ` H. Peter Anvin
2007-11-16 0:40 ` William Lee Irwin III
2007-11-16 0:41 ` H. Peter Anvin
2007-11-16 11:16 ` Andi Kleen
2007-11-16 15:45 ` H. Peter Anvin
2007-11-16 15:53 ` Andi Kleen
2007-11-16 16:10 ` H. Peter Anvin
2007-11-16 17:12 ` Jeremy Fitzhardinge
2007-11-16 17:35 ` Linus Torvalds
2007-11-16 18:30 ` Jeremy Fitzhardinge
2007-11-16 19:14 ` Jeremy Fitzhardinge
2007-11-16 19:22 ` Linus Torvalds
2007-11-16 19:43 ` Jeremy Fitzhardinge [this message]
2007-11-16 17:45 ` H. Peter Anvin
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