X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=blobdiff_plain;f=module%2Fzfs%2Ftxg.c;h=5702a61f04fe8dbd65f3294a3899ba6d7e6372ac;hb=920dd524fb2997225d4b1ac180bcbc14b045fda6;hp=6e64adf9376e5c97a8cfb823caf796c0c9cb6b8f;hpb=570827e129ed81e066e894530bbe24642f473154;p=zfs.git

diff --git a/module/zfs/txg.c b/module/zfs/txg.c
index 6e64adf..5702a61 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));
 
@@ -374,24 +384,22 @@ 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);
 
 	start = delta = 0;
 	for (;;) {
-		uint64_t timer, timeout = zfs_txg_timeout * hz;
+		uint64_t timer, timeout;
 		uint64_t txg;
 
+		timeout = zfs_txg_timeout * hz;
+
 		/*
 		 * We sync when we're scanning, there's someone waiting
 		 * on us, or the quiesce thread has handed off a txg to
@@ -767,4 +775,7 @@ EXPORT_SYMBOL(txg_wait_open);
 EXPORT_SYMBOL(txg_wait_callbacks);
 EXPORT_SYMBOL(txg_stalled);
 EXPORT_SYMBOL(txg_sync_waiting);
+
+module_param(zfs_txg_timeout, int, 0644);
+MODULE_PARM_DESC(zfs_txg_timeout, "Max seconds worth of delta per txg");
 #endif