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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>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.