Messages in this thread | | | Date | Mon, 05 Jun 2017 14:55:23 -0400 (EDT) | Subject | Re: [PATCH] sparc64: mm: fix copy_tsb to correctly copy huge page TSBs | From | David Miller <> |
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From: Mike Kravetz <mike.kravetz@oracle.com> Date: Fri, 2 Jun 2017 14:51:12 -0700
> 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>
Great find, applied and queued up for -stable.
Thanks!
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