From: Mike Kravetz <mike.krav...@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.yzn...@oracle.com> > Signed-off-by: Mike Kravetz <mike.krav...@oracle.com> Great find, applied and queued up for -stable. Thanks!
