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Date: Sat, 15 Mar 2014 16:17:58 +0530 From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com> To: benh@...nel.crashing.org, paulus@...ba.org, Rik van Riel <riel@...hat.com> Cc: linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com> Subject: [PATCH] powerpc/mm: Make sure a local_irq_disable prevent a parallel THP split From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com> 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@...ux.vnet.ibm.com> --- arch/powerpc/mm/pgtable_64.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c index 62bf5e8e78da..f6ce1f111f5b 100644 --- a/arch/powerpc/mm/pgtable_64.c +++ b/arch/powerpc/mm/pgtable_64.c @@ -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(); } /* -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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