diff options
authorVineet Gupta <Vineet.Gupta1@synopsys.com>2016-02-11 16:13:09 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-11 18:35:48 -0800
commit6a6ac72fd6ea32594b316513e1826c3f6db4cc93 (patch)
parent078c6c3a5e7dc53a9a23408cc32c83954abb5d0d (diff)
mm,thp: khugepaged: call pte flush at the time of collapse
This showed up on ARC when running LMBench bw_mem tests as Overlapping TLB Machine Check Exception triggered due to STLB entry (2M pages) overlapping some NTLB entry (regular 8K page). bw_mem 2m touches a large chunk of vaddr creating NTLB entries. In the interim khugepaged kicks in, collapsing the contiguous ptes into a single pmd. pmdp_collapse_flush()->flush_pmd_tlb_range() is called to flush out NTLB entries for the ptes. This for ARC (by design) can only shootdown STLB entries (for pmd). The stray NTLB entries cause the overlap with the subsequent STLB entry for collapsed page. So make pmdp_collapse_flush() call pte flush interface not pmd flush. Note that originally all thp flush call sites in generic code called flush_tlb_range() leaving it to architecture to implement the flush for pte and/or pmd. Commit 12ebc1581ad11454 changed this by calling a new opt-in API flush_pmd_tlb_range() which made the semantics more explicit but failed to distinguish the pte vs pmd flush in generic code, which is what this patch fixes. Note that ARC can fixed w/o touching the generic pmdp_collapse_flush() by defining a ARC version, but that defeats the purpose of generic version, plus sementically this is the right thing to do. Fixes STAR 9000961194: LMBench on AXS103 triggering duplicate TLB exceptions with super pages Fixes: 12ebc1581ad11454 ("mm,thp: introduce flush_pmd_tlb_range") Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> [4.4] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 9d4767698a1c..9f131c6034c5 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -195,7 +195,9 @@ pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
- flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+ /* collapse entails shooting down ptes not pmd */
+ flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
return pmd;