3.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: "David S. Miller" <da...@davemloft.net>
[ 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 <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/sparc/mm/init_64.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -351,6 +351,10 @@ void update_mmu_cache(struct vm_area_str
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);
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
@@ -2619,6 +2623,10 @@ void update_mmu_cache_pmd(struct vm_area
pte = pmd_val(entry);
+ /* Don't insert a non-valid PMD into the TSB, we'll deadlock. */
+ if (!(pte & _PAGE_VALID))
+ return;
+
/* We are fabricating 8MB pages using 4MB real hw pages. */
pte |= (addr & (1UL << REAL_HPAGE_SHIFT));
--
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