diff options
author | Hugh Dickins <hugh@veritas.com> | 2008-05-06 20:49:23 +0100 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-05-06 13:08:58 -0700 |
commit | aeed5fce37196e09b4dac3a1c00d8b7122e040ce (patch) | |
tree | d16a8f824ad06ac5dea6052f1986165a0d7fc865 /mm | |
parent | bb78be8397d3b0900af3d717672218ee3ea07985 (diff) | |
download | kernel_samsung_aries-aeed5fce37196e09b4dac3a1c00d8b7122e040ce.zip kernel_samsung_aries-aeed5fce37196e09b4dac3a1c00d8b7122e040ce.tar.gz kernel_samsung_aries-aeed5fce37196e09b4dac3a1c00d8b7122e040ce.tar.bz2 |
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>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/memory.c | 5 |
1 files changed, 4 insertions, 1 deletions
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; |