tree 7b642641514dc425102783a89870611e4f4c163e
parent 4bcea472de100311614c442f7236d0bcc4a413b3
author John David Anglin <dave.anglin@bell.net> 1481078824 -0500
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1481820561 -0800

parisc: Purge TLB before setting PTE

commit c78e710c1c9fbeff43dddc0aa3d0ff458e70b0cc upstream.

The attached change interchanges the order of purging the TLB and
setting the corresponding page table entry.  TLB purges are strongly
ordered.  It occurred to me one night that setting the PTE first might
have subtle ordering issues on SMP machines and cause random memory
corruption.

A TLB lock guards the insertion of user TLB entries.  So after the TLB
is purged, a new entry can't be inserted until the lock is released.
This ensures that the new PTE value is used when the lock is released.

Since making this change, no random segmentation faults have been
observed on the Debian hppa buildd servers.

Signed-off-by: John David Anglin  <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>