From: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com
[ Upstream commit 8f53f9c0f68ab2168f637494b9e24034899c1310 ]
With a 64K page size flush with start and end:
(start, end) = (721f680d0000, 721f680e0000)
results in:
(hstart, hend) = (721f68200000, 721f68000000)
ie. hstart is above hend, which indicates no huge page flush is needed.
However the current logic incorrectly sets hflush = true in this case, because hstart != hend.
That causes us to call __tlbie_va_range() passing hstart/hend, to do a huge page flush even though we don't need to. __tlbie_va_range() will skip the actual tlbie operation for start > end. But it will still end up calling fixup_tlbie_va_range() and doing the TLB fixups in there, which is harmless but unnecessary work.
Reported-by: Bharata B Rao bharata@linux.ibm.com Signed-off-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Reviewed-by: Nicholas Piggin npiggin@gmail.com [mpe: Drop else case, hflush is already false, flesh out change log] Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20200513030616.152288-1-aneesh.kumar@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/mm/book3s64/radix_tlb.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c index 758ade2c2b6ed..b5cc9b23cf024 100644 --- a/arch/powerpc/mm/book3s64/radix_tlb.c +++ b/arch/powerpc/mm/book3s64/radix_tlb.c @@ -884,9 +884,7 @@ is_local: if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { hstart = (start + PMD_SIZE - 1) & PMD_MASK; hend = end & PMD_MASK; - if (hstart == hend) - hflush = false; - else + if (hstart < hend) hflush = true; }