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f8a01513f5
MADV_COLLAPSE on a file mapping behaves inconsistently depending on if PMD page table is installed or not. Consider following example: p = mmap(NULL, 2UL << 20, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); err = madvise(p, 2UL << 20, MADV_COLLAPSE); fd is a populated tmpfs file. The result depends on the address that the kernel returns on mmap(). If it is located in an existing PMD table, the madvise() will succeed. However, if the table does not exist, it will fail with -EINVAL. This occurs because find_pmd_or_thp_or_none() returns SCAN_PMD_NULL when a page table is missing, which causes collapse_pte_mapped_thp() to fail. SCAN_PMD_NULL and SCAN_PMD_NONE should be treated the same in collapse_pte_mapped_thp(): install the PMD leaf entry and allocate page tables as needed. Link: https://lkml.kernel.org/r/v5ivpub6z2n2uyemlnxgbilzs52ep4lrary7lm7o6axxoneb75@yfacfl5rkzeh Signed-off-by: Kiryl Shutsemau <kas@kernel.org> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Dev Jain <dev.jain@arm.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Reviewed-by: Zach O'Keefe <zokeefe@google.com> Cc: Barry Song <baohua@kernel.org> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Mariano Pache <npache@redhat.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
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| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
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| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.