https://github.com/torvalds/linux
Revision d7df2443cd5f67fc6ee7c05a88e4996e8177f91b authored by Benjamin Herrenschmidt on 03 February 2017, 06:10:28 UTC, committed by Michael Ellerman on 08 February 2017, 12:36:29 UTC
When autonuma (Automatic NUMA balancing) marks a PTE inaccessible it
clears all the protection bits but leave the PTE valid.

With the Radix MMU, an attempt at executing from such a PTE will
take a fault with bit 35 of SRR1 set "SRR1_ISI_N_OR_G".

It is thus incorrect to treat all such faults as errors. We should
pass them to handle_mm_fault() for autonuma to deal with. The case
of pages that are really not executable is handled by the existing
test for VM_EXEC further down.

That leaves us with catching the kernel attempts at executing user
pages. We can catch that earlier, even before we do find_vma.

It is never valid on powerpc for the kernel to take an exec fault
to begin with. So fold that test with the existing test for the
kernel faulting on kernel addresses to bail out early.

Fixes: 1d18ad026844 ("powerpc/mm: Detect instruction fetch denied and report")
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
1 parent a0615a1
History
Tip revision: d7df2443cd5f67fc6ee7c05a88e4996e8177f91b authored by Benjamin Herrenschmidt on 03 February 2017, 06:10:28 UTC
powerpc/mm: Fix spurrious segfaults on radix with autonuma
Tip revision: d7df244
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