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powerpc/mm: Make sure a local_irq_disable prevent a parallel THP split

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We have generic code like the one in get_futex_key that assume that
a local_irq_disable prevents a parallel THP split. Support that by
adding a dummy smp call function after setting _PAGE_SPLITTING. Code
paths like get_user_pages_fast still need to check for _PAGE_SPLITTING
after disabling IRQ which indicate that a parallel THP splitting is
ongoing. Now if they don't find _PAGE_SPLITTING set, then we can be
sure that parallel split will now block in pmdp_splitting flush
until we enables IRQ

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Aneesh Kumar K.V 2014-03-15 16:17:58 +05:30 committed by Benjamin Herrenschmidt
parent ee4ed6fa5a
commit 346519a160
1 changed files with 5 additions and 0 deletions
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5
arch/powerpc/mm/pgtable_64.c
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@ -647,6 +647,11 @@ void pmdp_splitting_flush(struct vm_area_struct *vma,
if (old & _PAGE_HASHPTE)
hpte_do_hugepage_flush(vma->vm_mm, address, pmdp);
}
/*
* This ensures that generic code that rely on IRQ disabling
* to prevent a parallel THP split work as expected.
*/
kick_all_cpus_sync();
}
/*