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Subject[patch 17/60] x86: work around Fedora-11 x86-32 kernel failures on Intel Atom CPUs

-stable review patch. If anyone has any objections, please let us know.

------------------
From: Ingo Molnar <mingo@elte.hu>
commit 211b3d03c7400f48a781977a50104c9d12f4e229 upstream

[Trivial backport to 2.6.27 by cebbert@redhat.com]

x86: work around Fedora-11 x86-32 kernel failures on Intel Atom CPUs

Impact: work around boot crash

Work around Intel Atom erratum AAH41 (probabilistically) - it's triggering
in the field.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Kyle McMartin <kyle@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

---
arch/x86/mm/pageattr.c | 11 +++++++++++
1 file changed, 11 insertions(+)

--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -565,6 +565,17 @@ static int split_large_page(pte_t *kpte,
ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
pgprot_val(ref_prot) |= _PAGE_PRESENT;
__set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
+
+ /*
+ * Intel Atom errata AAH41 workaround.
+ *
+ * The real fix should be in hw or in a microcode update, but
+ * we also probabilistically try to reduce the window of having
+ * a large TLB mixed with 4K TLBs while instruction fetches are
+ * going on.
+ */
+ __flush_tlb_all();
+
base = NULL;

out_unlock:



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