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Michael Schmitz 3f90f9ef2d m68k/mm: Adjust VM area to be unmapped by gap size for __iounmap()
If 020/030 support is enabled, get_io_area() leaves an IO_SIZE gap
between mappings which is added to the vm_struct representing the
mapping.  __ioremap() uses the actual requested size (after alignment),
while __iounmap() is passed the size from the vm_struct.

On 020/030, early termination descriptors are used to set up mappings of
extent 'size', which are validated on unmapping. The unmapped gap of
size IO_SIZE defeats the sanity check of the pmd tables, causing
__iounmap() to loop forever on 030.

On 040/060, unmapping of page table entries does not check for a valid
mapping, so the umapping loop always completes there.

Adjust size to be unmapped by the gap that had been added in the
vm_struct prior.

This fixes the hang in atari_platform_init() reported a long time ago,
and a similar one reported by Finn recently (addressed by removing
ioremap() use from the SWIM driver.

Tested on my Falcon in 030 mode - untested but should work the same on
040/060 (the extra page tables cleared there would never have been set
up anyway).

Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
[geert: Minor commit description improvements]
[geert: This was fixed in 2.4.23, but not in 2.5.x]
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@vger.kernel.org
2018-05-24 12:00:27 +02:00
arch m68k/mm: Adjust VM area to be unmapped by gap size for __iounmap() 2018-05-24 12:00:27 +02:00
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Makefile Linux v4.17-rc3 2018-04-29 14:17:42 -07:00
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.