Revert Disable direct reclaim for z_wr_* threads

This commit used PF_MEMALLOC to prevent a memory reclaim deadlock.
However, commit 49be0ccf1fdc2ce852271d4d2f8b7a9c2c4be6db eliminated
the invocation of __cv_init(), which was the cause of the deadlock.
PF_MEMALLOC has the side effect of permitting pages from ZONE_DMA
to be allocated.  The use of PF_MEMALLOC was found to cause stability
problems when doing swap on zvols. Since this technique is known to
cause problems and no longer fixes anything, we revert it.

Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #726

diff --git a/include/sys/zfs_context.h b/include/sys/zfs_context.h
index 6201214..98b216f 100644 (file)
--- a/include/sys/zfs_context.h
+++ b/include/sys/zfs_context.h
@@ -388,7 +388,6 @@ typedef struct taskq_ent {
 #define        TASKQ_DYNAMIC           0x0004  /* Use dynamic thread scheduling */
 #define        TASKQ_THREADS_CPU_PCT   0x0008  /* Scale # threads by # cpus */
 #define        TASKQ_DC_BATCH          0x0010  /* Mark threads as batch */
-#define        TASKQ_NORECLAIM         0x0020  /* Disable direct memory reclaim */
 
 #define        TQ_SLEEP        KM_SLEEP        /* Can block for memory */
 #define        TQ_NOSLEEP      KM_NOSLEEP      /* cannot block for memory; may fail */

diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index 692664b..7abe699 100644 (file)
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -672,8 +672,9 @@ spa_get_errlists(spa_t *spa, avl_tree_t *last, avl_tree_t *scrub)
 
 static taskq_t *
 spa_taskq_create(spa_t *spa, const char *name, enum zti_modes mode,
-    uint_t value, uint_t flags)
+    uint_t value)
 {
+       uint_t flags = TASKQ_PREPOPULATE;
        boolean_t batch = B_FALSE;
 
        switch (mode) {
@@ -723,17 +724,13 @@ spa_create_zio_taskqs(spa_t *spa)
                        const zio_taskq_info_t *ztip = &zio_taskqs[t][q];
                        enum zti_modes mode = ztip->zti_mode;
                        uint_t value = ztip->zti_value;
-                       uint_t flags = 0;
                        char name[32];
 
-                       if (t == ZIO_TYPE_WRITE)
-                               flags |= TASKQ_NORECLAIM;
-
                        (void) snprintf(name, sizeof (name),
                            "%s_%s", zio_type_name[t], zio_taskq_types[q]);
 
                        spa->spa_zio_taskq[t][q] =
-                           spa_taskq_create(spa, name, mode, value, flags);
+                           spa_taskq_create(spa, name, mode, value);
                }
        }
 }