From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Thu, 26 Jul 2012 06:53:06 +0000 (+0200)
Subject: s390/mm: downgrade page table after fork of a 31 bit process
X-Git-Tag: v3.2.27~39
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f22027d0e8398e377a42a62241137b77a35eda97;p=pandora-kernel.git

s390/mm: downgrade page table after fork of a 31 bit process

commit 0f6f281b731d20bfe75c13f85d33f3f05b440222 upstream.

The downgrade of the 4 level page table created by init_new_context is
currently done only in start_thread31. If a 31 bit process forks the
new mm uses a 4 level page table, including the task size of 2<<42
that goes along with it. This is incorrect as now a 31 bit process
can map memory beyond 2GB. Define arch_dup_mmap to do the downgrade
after fork.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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