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commit 97d3d0f9a1cf132c63c0b8b8bd497b8a56283dd9 upstream. Patch series "Fix two above-47bit hint address vs. THP bugs". The two get_unmapped_area() implementations have to be fixed to provide THP-friendly mappings if above-47bit hint address is specified. This patch (of 2): Filesystems use thp_get_unmapped_area() to provide THP-friendly mappings. For DAX in particular. Normally, the kernel doesn't create userspace mappings above 47-bit, even if the machine allows this (such as with 5-level paging on x86-64). Not all user space is ready to handle wide addresses. It's known that at least some JIT compilers use higher bits in pointers to encode their information. Userspace can ask for allocation from full address space by specifying hint address (with or without MAP_FIXED) above 47-bits. If the application doesn't need a particular address, but wants to allocate from whole address space it can specify -1 as a hint address. Unfortunately, this trick breaks thp_get_unmapped_area(): the function would not try to allocate PMD-aligned area if *any* hint address specified. Modify the routine to handle it correctly: - Try to allocate the space at the specified hint address with length padding required for PMD alignment. - If failed, retry without length padding (but with the same hint address); - If the returned address matches the hint address return it. - Otherwise, align the address as required for THP and return. The user specified hint address is passed down to get_unmapped_area() so above-47bit hint address will be taken into account without breaking alignment requirements. Link: http://lkml.kernel.org/r/20191220142548.7118-2-kirill.shutemov@linux.intel.com Fixes: b569bab78d8d ("x86/mm: Prepare to expose larger address space to userspace") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Thomas Willhalm <thomas.willhalm@intel.com> Tested-by: Dan Williams <dan.j.williams@intel.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: "Bruggeman, Otto G" <otto.g.bruggeman@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@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.
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.