tree e447b00574b2519e5e4d981a2e0c709575200ce5
parent 4b684e6474d0137d00c555b51f9bb4299f3e29bb
author Mike Kravetz <mike.kravetz@oracle.com> 1496440272 -0700
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1497445553 +0200

sparc64: mm: fix copy_tsb to correctly copy huge page TSBs


[ Upstream commit 654f4807624a657f364417c2a7454f0df9961734 ]

When a TSB grows beyond its current capacity, a new TSB is allocated
and copy_tsb is called to copy entries from the old TSB to the new.
A hash shift based on page size is used to calculate the index of an
entry in the TSB.  copy_tsb has hard coded PAGE_SHIFT in these
calculations.  However, for huge page TSBs the value REAL_HPAGE_SHIFT
should be used.  As a result, when copy_tsb is called for a huge page
TSB the entries are placed at the incorrect index in the newly
allocated TSB.  When doing hardware table walk, the MMU does not
match these entries and we end up in the TSB miss handling code.
This code will then create and write an entry to the correct index
in the TSB.  We take a performance hit for the table walk miss and
recreation of these entries.

Pass a new parameter to copy_tsb that is the page size shift to be
used when copying the TSB.

Suggested-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>