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authorDavid S. Miller <davem@davemloft.net>2014-08-04 16:34:01 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-08-14 09:24:16 +0800
commit5b36a75bc06a00ede43bf8d9e921052357384072 (patch)
parent921df8ed4c86310d215b62579703cc89741d6361 (diff)
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>
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 04fd55a6e461..d6c1c85ff1c6 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -350,6 +350,10 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *
mm = vma->vm_mm;
+ /* Don't insert a non-valid PTE into the TSB, we'll deadlock. */
+ if (!pte_accessible(mm, pte))
+ return;
spin_lock_irqsave(&mm->context.lock, flags);