From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
PF_PK means that a memory access violated the protection key
access restrictions. It is unconditionally an access_error()
because the permissions set on the VMA don't matter (the PKRU
value overrides it), and we never "resolve" PK faults (like
how a COW can "resolve write fault).
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: linux-api@xxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: x86@xxxxxxxxxx
Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
Cc: akpm@xxxxxxxxxxxxxxxxxxxx
Cc: Arnd Bergmann <arnd@xxxxxxxx>
---
b/arch/x86/mm/fault.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff -puN arch/x86/mm/fault.c~pkeys-105-add-pk-to-fault arch/x86/mm/fault.c
--- a/arch/x86/mm/fault.c~pkeys-105-add-pk-to-fault 2016-07-29 09:18:55.920448993 -0700
+++ b/arch/x86/mm/fault.c 2016-07-29 09:18:55.923449129 -0700
@@ -1112,6 +1112,15 @@ access_error(unsigned long error_code, s
{
/* This is only called for the current mm, so: */
bool foreign = false;
+
+ /*
+ * Read or write was blocked by protection keys. This is
+ * always an unconditional error and can never result in
+ * a follow-up action to resolve the fault, like a COW.
+ */
+ if (error_code & PF_PK)
+ return 1;
+
/*
* Make sure to check the VMA so that we do not perform
* faults just to hit a PF_PK as soon as we fill in a
_
--
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