X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=blobdiff_plain;f=module%2Fzfs%2Ftxg.c;h=e14bff269b3e77a5c3421255f7a77ba89f2aebb5;hb=49d39798f286cce2497a87fc06d78c051ca87570;hp=d0d2b1716e88688df4d05857f537d2af7f0feb39;hpb=cddafdcbc55a38cdbdd3dc8c58f447b22bd847ee;p=zfs.git

diff --git a/module/zfs/txg.c b/module/zfs/txg.c
index d0d2b17..e14bff2 100644
--- a/module/zfs/txg.c
+++ b/module/zfs/txg.c
@@ -218,9 +218,19 @@ uint64_t
 txg_hold_open(dsl_pool_t *dp, txg_handle_t *th)
 {
 	tx_state_t *tx = &dp->dp_tx;
-	tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID];
+	tx_cpu_t *tc;
 	uint64_t txg;
 
+	/*
+	 * It appears the processor id is simply used as a "random"
+	 * number to index into the array, and there isn't any other
+	 * significance to the chosen tx_cpu. Because.. Why not use
+	 * the current cpu to index into the array?
+	 */
+	kpreempt_disable();
+	tc = &tx->tx_cpu[CPU_SEQID];
+	kpreempt_enable();
+
 	mutex_enter(&tc->tc_lock);
 
 	txg = tx->tx_open_txg;
@@ -339,7 +349,7 @@ txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
 			    TASKQ_THREADS_CPU_PCT | TASKQ_PREPOPULATE);
 		}
 
-		cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
+		cb_list = kmem_alloc(sizeof (list_t), KM_PUSHPAGE);
 		list_create(cb_list, sizeof (dmu_tx_callback_t),
 		    offsetof(dmu_tx_callback_t, dcb_node));
 
@@ -374,15 +384,11 @@ txg_sync_thread(dsl_pool_t *dp)
 
 #ifdef _KERNEL
 	/*
-	 * Disable the normal reclaim path for the txg_sync thread.  This
-	 * ensures the thread will never enter dmu_tx_assign() which can
-	 * otherwise occur due to direct reclaim.  If this is allowed to
-	 * happen the system can deadlock.  Direct reclaim call path:
-	 *
-	 *   ->shrink_icache_memory->prune_icache->dispose_list->
-	 *   clear_inode->zpl_clear_inode->zfs_inactive->dmu_tx_assign
+	 * Annotate this process with a flag that indicates that it is
+	 * unsafe to use KM_SLEEP during memory allocations due to the
+	 * potential for a deadlock.  KM_PUSHPAGE should be used instead.
 	 */
-	current->flags |= PF_MEMALLOC;
+	current->flags |= PF_NOFS;
 #endif /* _KERNEL */
 
 	txg_thread_enter(tx, &cpr);
@@ -524,6 +530,8 @@ txg_delay(dsl_pool_t *dp, uint64_t txg, int ticks)
 		(void) cv_timedwait(&tx->tx_quiesce_more_cv, &tx->tx_sync_lock,
 		    timeout);
 
+	DMU_TX_STAT_BUMP(dmu_tx_delay);
+
 	mutex_exit(&tx->tx_sync_lock);
 }