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1492c6b187
In the special case where
p = mmap(NULL, ALLOC_SIZE, PROT_READ,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
is followed by
rc = mprotect(p, ALLOC_SIZE, PROT_NONE);
the _PAGE_SPECIAL bit in the page tables will be cleared by
mistake and the later unmapped operations will incorrectly
modify the struct page for the the zero page. This sequence
occurs in the madvise05 test of the Linux Test Project
suite of tests.
This was discovered while testing an older version of the kernel
(5.4.17) on a MIPS device. Unfortunately, support for this device
is not available in newer kernels, so I can't test this with the
latest Linux kernel code. It looks like the problem exists in
newer kernels, but I can't verify it. Except for the LTP test,
this sequence of calls is probably not common.
Passing it along in the hope it will be useful to someone.
Signed-off-by: Henry Willard <henry.willard@oracle.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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.