Merge tag 'char-misc-5.15-rc1-lkdtm' of git://git.kernel.org/pub/scm/linux/kernel...

[linux-2.6-microblaze.git] / drivers / iommu / intel / svm.c

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 2014fe8..0c22878 100644 (file)
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -514,9 +514,6 @@ static void load_pasid(struct mm_struct *mm, u32 pasid)
 {
        mutex_lock(&mm->context.lock);
 
-       /* Synchronize with READ_ONCE in update_pasid(). */
-       smp_store_release(&mm->pasid, pasid);
-
        /* Update PASID MSR on all CPUs running the mm's tasks. */
        on_each_cpu_mask(mm_cpumask(mm), _load_pasid, NULL, true);
 
@@ -792,7 +789,19 @@ prq_retry:
                goto prq_retry;
        }
 
+       /*
+        * A work in IO page fault workqueue may try to lock pasid_mutex now.
+        * Holding pasid_mutex while waiting in iopf_queue_flush_dev() for
+        * all works in the workqueue to finish may cause deadlock.
+        *
+        * It's unnecessary to hold pasid_mutex in iopf_queue_flush_dev().
+        * Unlock it to allow the works to be handled while waiting for
+        * them to finish.
+        */
+       lockdep_assert_held(&pasid_mutex);
+       mutex_unlock(&pasid_mutex);
        iopf_queue_flush_dev(dev);
+       mutex_lock(&pasid_mutex);
 
        /*
         * Perform steps described in VT-d spec CH7.10 to drain page