From: David S. Miller Date: Mon, 4 Aug 2014 23:34:01 +0000 (-0700) Subject: sparc64: Do not insert non-valid PTEs into the TSB hash table. X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5b36a75bc06a00ede43bf8d9e921052357384072;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git 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 Signed-off-by: Greg Kroah-Hartman --- 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); #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)