From: Rusty Russell <rusty@rustcorp.com.au>
To: virtualization@lists.linux-foundation.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
virtualization@lists.osdl.org, akpm@osdl.org,
nickpiggin@yahoo.com.au, frankeh@watson.ibm.com,
hugh@veritas.com
Subject: Re: [patch 1/6] Guest page hinting: core + volatile page cache.
Date: Thu, 13 Mar 2008 10:12:22 +1100 [thread overview]
Message-ID: <200803131012.23420.rusty@rustcorp.com.au> (raw)
In-Reply-To: <20080312132703.132176945@de.ibm.com>
On Thursday 13 March 2008 00:21:33 Martin Schwidefsky wrote:
> @@ -957,6 +975,19 @@ struct page *follow_page(struct vm_area_
>
> if (flags & FOLL_GET)
> get_page(page);
> +
> + if (flags & FOLL_GET) {
> + /*
> + * The page is made stable if a reference is acquired.
> + * If the caller does not get a reference it implies that
> + * the caller can deal with page faults in case the page
> + * is swapped out. In this case the caller can deal with
> + * discard faults as well.
> + */
> + if (unlikely(!page_make_stable(page)))
> + goto out_discard;
> + }
Dumb comment: seems like this if could be folded into the one above.
> + * Attempts to change the state of a page to volatile.
> + * If there is something preventing the state change the page stays
> + * int its current state.
Typo "int its current state".
> return NULL;
>
> pte = pte_offset_map(pmd, address);
> + ptl = pte_lockptr(mm, pmd);
> /* Make a quick check before getting the lock */
> +#ifndef CONFIG_PAGE_STATES
> + /*
> + * If the page table lock for this pte is taken we have to
> + * assume that someone might be mapping the page. To solve
> + * the race of a page discard vs. mapping the page we have
> + * to serialize the two operations by taking the lock,
> + * otherwise we end up with a pte for a page that has been
> + * removed from page cache by the discard fault handler.
> + */
> + if (!spin_is_locked(ptl))
> +#endif
> if (!pte_present(*pte)) {
> pte_unmap(pte);
> return NULL;
> }
>
> - ptl = pte_lockptr(mm, pmd);
> spin_lock(ptl);
> if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
> *ptlp = ptl;
Did you really mean ifndef here?
(BTW: I'm just reading through the code, not really understanding it, so
this is not a real review).
Cheers,
Rusty.
next prev parent reply other threads:[~2008-03-12 23:13 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-12 13:21 [patch 0/6] Guest page hinting version 6 Martin Schwidefsky
2008-03-12 13:21 ` [patch 1/6] Guest page hinting: core + volatile page cache Martin Schwidefsky
2008-03-12 23:12 ` Rusty Russell [this message]
2008-03-13 9:24 ` Martin Schwidefsky
2008-03-12 13:21 ` [patch 2/6] Guest page hinting: volatile swap cache Martin Schwidefsky
2008-03-12 13:21 ` [patch 3/6] Guest page hinting: mlocked pages Martin Schwidefsky
2008-03-12 23:27 ` Rusty Russell
2008-03-13 9:13 ` Martin Schwidefsky
2008-03-12 13:21 ` [patch 4/6] Guest page hinting: writable page table entries Martin Schwidefsky
2008-03-12 23:35 ` Rusty Russell
2008-03-13 9:11 ` Martin Schwidefsky
2008-03-12 13:21 ` [patch 5/6] Guest page hinting: minor fault optimization Martin Schwidefsky
2008-03-12 13:21 ` [patch 6/6] Guest page hinting: s390 support Martin Schwidefsky
2008-03-12 16:19 ` Jeremy Fitzhardinge
2008-03-12 16:28 ` Martin Schwidefsky
2008-03-12 16:44 ` Jeremy Fitzhardinge
2008-03-12 16:59 ` Martin Schwidefsky
2008-03-12 17:48 ` Jeremy Fitzhardinge
2008-03-12 20:04 ` Anthony Liguori
2008-03-12 20:45 ` Jeremy Fitzhardinge
2008-03-12 20:56 ` Anthony Liguori
2008-03-12 21:36 ` Jeremy Fitzhardinge
2008-03-13 9:45 ` Martin Schwidefsky
2008-03-13 16:07 ` Jeremy Fitzhardinge
2008-03-13 16:17 ` Jeremy Fitzhardinge
2008-03-13 16:55 ` Martin Schwidefsky
2008-03-13 17:05 ` Jeremy Fitzhardinge
2008-03-13 17:23 ` Martin Schwidefsky
2008-03-13 9:42 ` Martin Schwidefsky
2008-03-13 9:36 ` Martin Schwidefsky
2008-03-13 9:32 ` Martin Schwidefsky
2008-03-12 22:41 ` [patch 0/6] Guest page hinting version 6 Rusty Russell
2008-03-13 9:47 ` Martin Schwidefsky
2008-03-13 16:57 ` Hugh Dickins
2008-03-13 17:14 ` Martin Schwidefsky
2008-03-13 17:45 ` Zachary Amsden
2008-03-13 19:45 ` Andrea Arcangeli
2008-03-13 21:41 ` Zachary Amsden
2008-03-13 18:41 ` Jeremy Fitzhardinge
2008-03-13 18:55 ` Hugh Dickins
2008-03-13 19:53 ` Zachary Amsden
2008-03-14 18:30 ` Jeremy Fitzhardinge
2008-03-14 21:32 ` Zachary Amsden
2008-03-14 21:37 ` Jeremy Fitzhardinge
2008-03-17 9:21 ` Martin Schwidefsky
2008-05-06 15:33 ` Martin Schwidefsky
2008-05-06 19:46 ` Rik van Riel
2008-05-07 3:49 ` Zachary Amsden
2008-05-07 7:00 ` Martin Schwidefsky
-- strict thread matches above, loose matches on Subject: below --
2009-03-27 15:09 [patch 0/6] Guest page hinting version 7 Martin Schwidefsky
2009-03-27 15:09 ` [patch 1/6] Guest page hinting: core + volatile page cache Martin Schwidefsky
2009-03-27 22:57 ` Rik van Riel
2009-03-29 13:56 ` Martin Schwidefsky
2009-03-29 14:35 ` Rik van Riel
2007-06-28 16:40 [patch 0/6] resend: guest page hinting version 5 Martin Schwidefsky
2007-06-28 16:40 ` [patch 1/6] Guest page hinting: core + volatile page cache Martin Schwidefsky
2007-05-11 13:58 [patch 0/6] [rfc] guest page hinting version 5 Martin Schwidefsky
2007-05-11 13:58 ` [patch 1/6] Guest page hinting: core + volatile page cache Martin Schwidefsky
2007-05-11 14:45 ` Valdis.Kletnieks
2007-05-11 14:53 ` Martin Schwidefsky
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