mirror of
https://github.com/torvalds/linux.git
synced 2025-12-07 20:06:24 +00:00
27bfafac65
The page tables used to map the kernel and userspace often have very different handling rules. There are frequently *_kernel() variants of functions just for kernel page tables. That's not great and has lead to code duplication. Instead of having completely separate call paths, allow a 'ptdesc' to be marked as being for kernel mappings. Introduce helpers to set and clear this status. Note: this uses the PG_referenced bit. Page flags are a great fit for this since it is truly a single bit of information. Use PG_referenced itself because it's a fairly benign flag (as opposed to things like PG_lock). It's also (according to Willy) unlikely to go away any time soon. PG_referenced is not in PAGE_FLAGS_CHECK_AT_FREE. It does not need to be cleared before freeing the page, and pages coming out of the allocator should have it cleared. Regardless, introduce an API to clear it anyway. Having symmetry in the API makes it easier to change the underlying implementation later, like if there was a need to move to a PAGE_FLAGS_CHECK_AT_FREE bit. Link: https://lkml.kernel.org/r/20251022082635.2462433-3-baolu.lu@linux.intel.com Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Alistair Popple <apopple@nvidia.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Betkov <bp@alien8.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org> Cc: Joerg Roedel <joro@8bytes.org> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Robin Murohy <robin.murphy@arm.com> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com> Cc: Vasant Hegde <vasant.hegde@amd.com> Cc: Vinicius Costa Gomes <vinicius.gomes@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Cc: Yi Lai <yi1.lai@intel.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.