sparc64: Do not insert non-valid PTEs into the TSB hash table.
[ Upstream commit 18f38132528c3e603c66ea464727b29e9bbcb91b ]
The assumption was that update_mmu_cache() (and the equivalent for PMDs) would
only be called when the PTE being installed will be accessible by the user.
This is not true for code paths originating from remove_migration_pte().
There are dire consequences for placing a non-valid PTE into the TSB. The TLB
miss frramework assumes thatwhen a TSB entry matches we can just load it into
the TLB and return from the TLB miss trap.
So if a non-valid PTE is in there, we will deadlock taking the TLB miss over
and over, never satisfying the miss.
Just exit early from update_mmu_cache() and friends in this situation.
Based upon a report and patch from Christopher Alexander Tobias Schulze.
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 7f8238f..9ed22b5 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -308,6 +308,10 @@
tsb_index = MM_TSB_BASE;
tsb_hash_shift = PAGE_SHIFT;
+ /* Don't insert a non-valid PTE into the TSB, we'll deadlock. */
+ if (!(pte_val(pte) & _PAGE_VALID))
+ return;
+
spin_lock_irqsave(&mm->context.lock, flags);
#ifdef CONFIG_HUGETLB_PAGE