a5704e83aa
When partition scope mappings are unmapped with kvm_unmap_radix, the pte is cleared, but the page table structure is left in place. If the next page fault requests a different page table geometry (e.g., due to THP promotion or split), kvmppc_create_pte is responsible for changing the page tables. When a page table entry is to be converted to a large pte, the page table entry is cleared, the PWC flushed, then the page table it points to freed. This will cause pte page tables to leak when a 1GB page is to replace a pud entry points to a pmd table with pte tables under it: The pmd table will be freed, but its pte tables will be missed. Fix this by replacing the simple clear and free code with one that walks down the page tables and frees children. Care must be taken to clear the root entry being unmapped then flushing the PWC before freeing any page tables, as explained in comments. This requires PWC flush to logically become a flush-all-PWC (which it already is in hardware, but the KVM API needs to be changed to avoid confusion). This code also checks that no unexpected pte entries exist in any page table being freed, and unmaps those and emits a WARN. This is an expensive operation for the pte page level, but partition scope changes are rare, so it's unconditional for now to iron out bugs. It can be put under a CONFIG option or removed after some time. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| 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 Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
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.