| From | Jiri Slaby <> | Subject | [PATCH 3.12 053/104] sparc64: Do not insert non-valid PTEs into the TSB hash table. | Date | Wed, 20 Aug 2014 13:43:16 +0200 |
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From: "David S. Miller" <davem@davemloft.net>
3.12-stable review patch. If anyone has any objections, please let me know.
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[ 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: Jiri Slaby <jslaby@suse.cz> --- arch/sparc/mm/init_64.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c index ed82edad1a39..774ba41dba4d 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); #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) -- 2.0.4
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