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Patch series "Fix set_huge_pte_at()". A recent report [1] from Ryan for arm64 revealed that we do not handle swap entries when setting a hugepage backed by a NAPOT region (the contpte riscv equivalent). As explained in [1], the issue was discovered by a new test in kselftest which uses poison entries, but the symptoms are different from arm64 though: - the riscv kernel bugs because we do not handle VM_FAULT_HWPOISON*, this is fixed by patch 1, - after that, the test passes because the first pte_napot() fails (the poison entry does not have the N bit set), and then we only set the first page table entry covering the NAPOT hugepage, which is enough for hugetlb_fault() to correctly raise a VM_FAULT_HWPOISON wherever we write in this mapping since only this first page table entry is checked (see https://elixir.bootlin.com/linux/v6.6-rc3/source/mm/hugetlb.c#L6071). But this seems fragile so patch 2 sets all page table entries of a NAPOT mapping. [1]: https://lore.kernel.org/linux-arm-kernel/20230922115804.2043771-1-ryan.roberts@arm.com/ This patch (of 2): We used to panic when such faults were encountered but we should handle those faults gracefully for userspace by sending a SIGBUS to the process, like most architectures do. Link: https://lkml.kernel.org/r/20230928151846.8229-1-alexghiti@rivosinc.com Link: https://lkml.kernel.org/r/20230928151846.8229-2-alexghiti@rivosinc.com Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Acked-by: Palmer Dabbelt <palmer@rivosinc.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Andrew Jones <ajones@ventanamicro.com> Cc: Conor Dooley <conor@kernel.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Qinglin Pan <panqinglin2020@iscas.ac.cn> 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 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.