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d2d0ecb944
commit 48381273f8734d28ef56a5bdf1966dd8530111bc upstream. The routine huge_pmd_unshare() is passed a pointer to an address associated with an area which may be unshared. If unshare is successful this address is updated to 'optimize' callers iterating over huge page addresses. For the optimization to work correctly, address should be updated to the last huge page in the unmapped/unshared area. However, in the common case where the passed address is PUD_SIZE aligned, the address is incorrectly updated to the address of the preceding huge page. That wastes CPU cycles as the unmapped/unshared range is scanned twice. Link: https://lkml.kernel.org/r/20220524205003.126184-1-mike.kravetz@oracle.com Fixes: 39dde65c9940 ("shared page table for hugetlb page") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Muchun Song <songmuchun@bytedance.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
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.