Attachment 311837 Details for Bug 455434 – Upstream fix for this issue

[patch] Upstream fix for this issue

1319 (text/plain), 7.50 KB, created by Prarit Bhargava on 2008-07-15 14:18:08 UTC

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Creator: Prarit Bhargava

Created: 2008-07-15 14:18:08 UTC

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patch

obsolete

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>Date:	Tue, 6 May 2008 22:00:01 GMT
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>From:	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
>To:	git-commits-head@vger.kernel.org
>Subject: x86: fix PAE pmd_bad bootup warning
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>X-Git-Commit: aeed5fce37196e09b4dac3a1c00d8b7122e040ce
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>Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=aeed5fce37196e09b4dac3a1c00d8b7122e040ce
>Commit:     aeed5fce37196e09b4dac3a1c00d8b7122e040ce
>Parent:     bb78be8397d3b0900af3d717672218ee3ea07985
>Author:     Hugh Dickins <hugh@veritas.com>
>AuthorDate: Tue May 6 20:49:23 2008 +0100
>Committer:  Linus Torvalds <torvalds@linux-foundation.org>
>CommitDate: Tue May 6 13:08:58 2008 -0700
>
>    x86: fix PAE pmd_bad bootup warning
>    
>    Fix warning from pmd_bad() at bootup on a HIGHMEM64G HIGHPTE x86_32.
>    
>    That came from 9fc34113f6880b215cbea4e7017fc818700384c2 x86: debug pmd_bad();
>    but we understand now that the typecasting was wrong for PAE in the previous
>    version: pagetable pages above 4GB looked bad and stopped Arjan from booting.
>    
>    And revert that cded932b75ab0a5f9181ee3da34a0a488d1a14fd x86: fix pmd_bad
>    and pud_bad to support huge pages.  It was the wrong way round: we shouldn't
>    weaken every pmd_bad and pud_bad check to let huge pages slip through - in
>    part they check that we _don't_ have a huge page where it's not expected.
>    
>    Put the x86 pmd_bad() and pud_bad() definitions back to what they have long
>    been: they can be improved (x86_32 should use PTE_MASK, to stop PAE thinking
>    junk in the upper word is good; and x86_64 should follow x86_32's stricter
>    comparison, to stop thinking any subset of required bits is good); but that
>    should be a later patch.
>    
>    Fix Hans' good observation that follow_page() will never find pmd_huge()
>    because that would have already failed the pmd_bad test: test pmd_huge in
>    between the pmd_none and pmd_bad tests.  Tighten x86's pmd_huge() check?
>    No, once it's a hugepage entry, it can get quite far from a good pmd: for
>    example, PROT_NONE leaves it with only ACCESSED of the KERN_PGTABLE bits.
>    
>    However... though follow_page() contains this and another test for huge
>    pages, so it's nice to keep it working on them, where does it actually get
>    called on a huge page?  get_user_pages() checks is_vm_hugetlb_page(vma) to
>    to call alternative hugetlb processing, as does unmap_vmas() and others.
>    
>    Signed-off-by: Hugh Dickins <hugh@veritas.com>
>    Earlier-version-tested-by: Ingo Molnar <mingo@elte.hu>
>    Cc: Thomas Gleixner <tglx@linutronix.de>
>    Cc: Jeff Chua <jeff.chua.linux@gmail.com>
>    Cc: Hans Rosenfeld <hans.rosenfeld@amd.com>
>    Cc: Arjan van de Ven <arjan@linux.intel.com>
>    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
>---
> arch/x86/mm/pgtable_32.c     |    7 -------
> include/asm-x86/pgtable_32.h |    9 +--------
> include/asm-x86/pgtable_64.h |    6 ++----
> mm/memory.c                  |    5 ++++-
> 4 files changed, 7 insertions(+), 20 deletions(-)
>
>diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
>index 9ee007b..369cf06 100644
>--- a/arch/x86/mm/pgtable_32.c
>+++ b/arch/x86/mm/pgtable_32.c
>@@ -172,10 +172,3 @@ void reserve_top_address(unsigned long reserve)
> 	__FIXADDR_TOP = -reserve - PAGE_SIZE;
> 	__VMALLOC_RESERVE += reserve;
> }
>-
>-int pmd_bad(pmd_t pmd)
>-{
>-	WARN_ON_ONCE(pmd_bad_v1(pmd) != pmd_bad_v2(pmd));
>-
>-	return pmd_bad_v1(pmd);
>-}
>diff --git a/include/asm-x86/pgtable_32.h b/include/asm-x86/pgtable_32.h
>index 577ab79..d7f0403 100644
>--- a/include/asm-x86/pgtable_32.h
>+++ b/include/asm-x86/pgtable_32.h
>@@ -88,14 +88,7 @@ extern unsigned long pg0[];
> /* To avoid harmful races, pmd_none(x) should check only the lower when PAE */
> #define pmd_none(x)	(!(unsigned long)pmd_val((x)))
> #define pmd_present(x)	(pmd_val((x)) & _PAGE_PRESENT)
>-
>-extern int pmd_bad(pmd_t pmd);
>-
>-#define pmd_bad_v1(x)							\
>-	(_KERNPG_TABLE != (pmd_val((x)) & ~(PAGE_MASK | _PAGE_USER)))
>-#define	pmd_bad_v2(x)							\
>-	(_KERNPG_TABLE != (pmd_val((x)) & ~(PAGE_MASK | _PAGE_USER |	\
>-					    _PAGE_PSE | _PAGE_NX)))
>+#define pmd_bad(x) ((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
> 
> #define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT))
> 
>diff --git a/include/asm-x86/pgtable_64.h b/include/asm-x86/pgtable_64.h
>index a3bbf87..efe83dc 100644
>--- a/include/asm-x86/pgtable_64.h
>+++ b/include/asm-x86/pgtable_64.h
>@@ -158,14 +158,12 @@ static inline unsigned long pgd_bad(pgd_t pgd)
> 
> static inline unsigned long pud_bad(pud_t pud)
> {
>-	return pud_val(pud) &
>-		~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER | _PAGE_PSE | _PAGE_NX);
>+	return pud_val(pud) & ~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER);
> }
> 
> static inline unsigned long pmd_bad(pmd_t pmd)
> {
>-	return pmd_val(pmd) &
>-		~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER | _PAGE_PSE | _PAGE_NX);
>+	return pmd_val(pmd) & ~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER);
> }
> 
> #define pte_none(x)	(!pte_val((x)))
>diff --git a/mm/memory.c b/mm/memory.c
>index bbab1e3..48c122d 100644
>--- a/mm/memory.c
>+++ b/mm/memory.c
>@@ -969,7 +969,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
> 		goto no_page_table;
> 	
> 	pmd = pmd_offset(pud, address);
>-	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
>+	if (pmd_none(*pmd))
> 		goto no_page_table;
> 
> 	if (pmd_huge(*pmd)) {
>@@ -978,6 +978,9 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
> 		goto out;
> 	}
> 
>+	if (unlikely(pmd_bad(*pmd)))
>+		goto no_page_table;
>+
> 	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
> 	if (!ptep)
> 		goto out;
>--
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Attachments on bug 455434: 311837 | 312348