powerpc/64s/hash: Fix fork() with 512TB process address space

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commit effc1b2508 upstream.

Hash unconditionally resets the addr_limit to default (128TB) when the
mm context is initialised. If a process has > 128TB mappings when it
forks, the child will not get the 512TB addr_limit, so accesses to
valid > 128TB mappings will fail in the child.

Fix this by only resetting the addr_limit to default if it was 0. Non
zero indicates it was duplicated from the parent (0 means exec()).

Fixes: f4ea6dcb08 ("powerpc/mm: Enable mappings above 128TB")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Nicholas Piggin 2017-11-10 04:27:37 +11:00 • committed by Greg Kroah-Hartman

parent 2279e9c895

commit 34c8d3ffb6

1 changed files with 4 additions and 4 deletions

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arch/powerpc/mm/mmu_context_book3s64.c

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