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Commited48e87c7d("thp: add thp_get_unmapped_area_vmflags()") changes thp_get_unmapped_area() to thp_get_unmapped_area_vmflags() in __get_unmapped_area(), which doesn't initialize local get_area for anonymous mappings. This leads to us always trying THP alignment even for file_operations which have a NULL ->get_unmapped_area() callback. Since commitefa7df3e3b("mm: align larger anonymous mappings on THP boundaries") we only want to enable THP alignment for anonymous mappings, so add a !file check to avoid attempting THP alignment for file mappings. Found issue by code inspection. THP alignment is used for easy or more pmd mappings, from vma side. This may cause unnecessary VMA fragmentation and potentially worse performance on filesystems that do not actually support THPs and thus cannot benefit from the alignment. Link: https://lkml.kernel.org/r/20241206070345.2526501-1-wangkefeng.wang@huawei.com Fixes:ed48e87c7d("thp: add thp_get_unmapped_area_vmflags()") Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: David Hildenbrand <david@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Rick Edgecombe <rick.p.edgecombe@intel.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.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 reStructuredText 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.