From: aarcange@redhat.com
To: linux-mm@kvack.org
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mel@csn.ul.ie>
Subject: [patch 16/35] bail out gup_fast on splitting pmd
Date: Fri, 26 Feb 2010 21:04:49 +0100 [thread overview]
Message-ID: <20100226200901.445609244@redhat.com> (raw)
In-Reply-To: 20100226200433.516502198@redhat.com
[-- Attachment #1: gup_fast_bail_out --]
[-- Type: text/plain, Size: 1427 bytes --]
From: Andrea Arcangeli <aarcange@redhat.com>
Force gup_fast to take the slow path and block if the pmd is splitting, not
only if it's none.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---
arch/x86/mm/gup.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -160,7 +160,18 @@ static int gup_pmd_range(pud_t pud, unsi
pmd_t pmd = *pmdp;
next = pmd_addr_end(addr, end);
- if (pmd_none(pmd))
+ /*
+ * The pmd_trans_splitting() check below explains why
+ * pmdp_splitting_flush has to flush the tlb, to stop
+ * this gup-fast code from running while we set the
+ * splitting bit in the pmd. Returning zero will take
+ * the slow path that will call wait_split_huge_page()
+ * if the pmd is still in splitting state. gup-fast
+ * can't because it has irq disabled and
+ * wait_split_huge_page() would never return as the
+ * tlb flush IPI wouldn't run.
+ */
+ if (pmd_none(pmd) || pmd_trans_splitting(pmd))
return 0;
if (unlikely(pmd_large(pmd))) {
if (!gup_huge_pmd(pmd, addr, next, write, pages, nr))
--
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next prev parent reply other threads:[~2010-02-26 20:09 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-26 20:04 [patch 00/35] Transparent Hugepage support #12 aarcange
2010-02-26 20:04 ` [patch 01/35] define MADV_HUGEPAGE aarcange
2010-02-26 20:04 ` [patch 02/35] compound_lock aarcange
2010-02-26 20:04 ` [patch 03/35] alter compound get_page/put_page aarcange
2010-02-26 20:04 ` [patch 04/35] update futex compound knowledge aarcange
2010-02-26 20:04 ` [patch 05/35] fix bad_page to show the real reason the page is bad aarcange
2010-02-26 20:04 ` [patch 06/35] clear compound mapping aarcange
2010-02-26 20:04 ` [patch 07/35] add native_set_pmd_at aarcange
2010-02-26 20:04 ` [patch 08/35] add pmd paravirt ops aarcange
2010-02-26 20:04 ` [patch 09/35] no paravirt version of pmd ops aarcange
2010-02-26 20:04 ` [patch 10/35] export maybe_mkwrite aarcange
2010-02-26 20:04 ` [patch 11/35] comment reminder in destroy_compound_page aarcange
2010-02-26 20:04 ` [patch 12/35] config_transparent_hugepage aarcange
2010-02-26 20:04 ` [patch 13/35] special pmd_trans_* functions aarcange
2010-02-26 20:04 ` [patch 14/35] add pmd mangling generic functions aarcange
2010-02-26 20:04 ` [patch 15/35] add pmd mangling functions to x86 aarcange
2010-02-26 20:04 ` aarcange [this message]
2010-02-26 20:04 ` [patch 17/35] pte alloc trans splitting aarcange
2010-02-26 20:04 ` [patch 18/35] add pmd mmu_notifier helpers aarcange
2010-02-26 20:04 ` [patch 19/35] clear page compound aarcange
2010-02-26 20:04 ` [patch 20/35] add pmd_huge_pte to mm_struct aarcange
2010-02-26 20:04 ` [patch 21/35] split_huge_page_mm/vma aarcange
2010-02-26 20:04 ` [patch 22/35] split_huge_page paging aarcange
2010-02-26 20:04 ` [patch 23/35] clear_copy_huge_page aarcange
2010-02-26 20:04 ` [patch 24/35] kvm mmu transparent hugepage support aarcange
2010-02-26 20:04 ` [patch 25/35] _GFP_NO_KSWAPD aarcange
2010-02-26 20:04 ` [patch 26/35] dont alloc harder for gfp nomemalloc even if nowait aarcange
2010-02-26 20:05 ` [patch 27/35] transparent hugepage core aarcange
2010-02-26 20:05 ` [patch 28/35] adapt to mm_counter in -mm aarcange
2010-02-26 20:05 ` [patch 29/35] verify pmd_trans_huge isnt leaking aarcange
2010-02-26 20:05 ` [patch 30/35] madvise(MADV_HUGEPAGE) aarcange
2010-02-26 20:05 ` [patch 31/35] pmd_trans_huge migrate bugcheck aarcange
2010-02-26 20:05 ` [patch 32/35] memcg compound aarcange
2010-02-26 20:05 ` [patch 33/35] memcg huge memory aarcange
2010-02-26 20:05 ` [patch 34/35] transparent hugepage vmstat aarcange
2010-02-26 20:05 ` [patch 35/35] khugepaged aarcange
-- strict thread matches above, loose matches on Subject: below --
2010-03-09 19:39 [patch 00/35] Transparent Hugepage support #13 aarcange
2010-03-09 19:39 ` [patch 16/35] bail out gup_fast on splitting pmd aarcange
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