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Index: sys/vm/swap_pager.c
===================================================================
--- sys/vm/swap_pager.c
+++ sys/vm/swap_pager.c
@@ -486,7 +486,8 @@
/*
* Metadata functions
*/
-static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
+static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t,
+ bool);
static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t,
vm_size_t *);
static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst,
@@ -1031,7 +1032,7 @@
}
for (j = 0; j < n; ++j) {
addr = swp_pager_meta_build(object,
- start + i + j, blk + j);
+ start + i + j, blk + j, false);
if (addr != SWAPBLK_NONE)
swp_pager_update_freerange(&range, addr);
}
@@ -1041,35 +1042,6 @@
return (0);
}
-static bool
-swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject,
- vm_pindex_t pindex, daddr_t addr)
-{
- daddr_t dstaddr __diagused;
-
- KASSERT((srcobject->flags & OBJ_SWAP) != 0,
- ("%s: srcobject not swappable", __func__));
- KASSERT((dstobject->flags & OBJ_SWAP) != 0,
- ("%s: dstobject not swappable", __func__));
-
- if (swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) {
- /* Caller should destroy the source block. */
- return (false);
- }
-
- /*
- * Destination has no swapblk and is not resident, transfer source.
- * swp_pager_meta_build() can sleep.
- */
- VM_OBJECT_WUNLOCK(srcobject);
- dstaddr = swp_pager_meta_build(dstobject, pindex, addr);
- KASSERT(dstaddr == SWAPBLK_NONE,
- ("Unexpected destination swapblk"));
- VM_OBJECT_WLOCK(srcobject);
-
- return (true);
-}
-
/*
* SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
* and destroy the source.
@@ -1548,7 +1520,7 @@
mreq = ma[i + j];
vm_page_aflag_clear(mreq, PGA_SWAP_FREE);
addr = swp_pager_meta_build(mreq->object, mreq->pindex,
- blk + j);
+ blk + j, false);
if (addr != SWAPBLK_NONE)
swp_pager_update_freerange(&range, addr);
MPASS(mreq->dirty == VM_PAGE_BITS_ALL);
@@ -2052,106 +2024,106 @@
uma_zfree(swblk_zone, sb);
}
}
-
+
+/*
+ * SWP_PAGER_ALLOC_WAIT() - wait before retrying allocation from a zone.
+ */
+static void
+swp_pager_alloc_wait(vm_object_t object, uma_zone_t zone,
+ volatile int *zone_exhausted, const char *errmsg, const char *pausemsg)
+{
+ VM_OBJECT_WUNLOCK(object);
+ if (uma_zone_exhausted(zone)) {
+ if (atomic_cmpset_int(zone_exhausted, 0, 1))
+ printf("swap %s zone exhausted, "
+ "increase kern.maxswzone\n", errmsg);
+ vm_pageout_oom(VM_OOM_SWAPZ);
+ pause(pausemsg, 10);
+ } else
+ uma_zwait(zone);
+ VM_OBJECT_WLOCK(object);
+}
+
/*
* SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
*
- * The specified swapblk is added to the object's swap metadata. If
- * the swapblk is not valid, it is freed instead. Any previously
- * assigned swapblk is returned.
+ * Try to add the specified swapblk to the object's swap metadata. If
+ * nowait and memory allocation fails, return the specified swapblk
+ * immediately to indicate failure. If nowait, add the specified swapblk
+ * only if there is no previously assigned swapblk. Return the previously
+ * assigned swapblk, if any.
*/
static daddr_t
-swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
+swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk,
+ bool nowait)
{
static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted;
struct swblk *sb, *sb1;
vm_pindex_t modpi, rdpi;
daddr_t prev_swapblk;
- int error, i;
+ int i;
VM_OBJECT_ASSERT_WLOCKED(object);
rdpi = rounddown(pindex, SWAP_META_PAGES);
sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi);
- if (sb == NULL) {
- if (swapblk == SWAPBLK_NONE)
- return (SWAPBLK_NONE);
- for (;;) {
- sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc ==
- pageproc ? M_USE_RESERVE : 0));
- if (sb != NULL) {
- sb->p = rdpi;
- for (i = 0; i < SWAP_META_PAGES; i++)
- sb->d[i] = SWAPBLK_NONE;
- if (atomic_cmpset_int(&swblk_zone_exhausted,
- 1, 0))
- printf("swblk zone ok\n");
- break;
- }
- VM_OBJECT_WUNLOCK(object);
- if (uma_zone_exhausted(swblk_zone)) {
- if (atomic_cmpset_int(&swblk_zone_exhausted,
- 0, 1))
- printf("swap blk zone exhausted, "
- "increase kern.maxswzone\n");
- vm_pageout_oom(VM_OOM_SWAPZ);
- pause("swzonxb", 10);
- } else
- uma_zwait(swblk_zone);
- VM_OBJECT_WLOCK(object);
- sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
- rdpi);
- if (sb != NULL)
- /*
- * Somebody swapped out a nearby page,
- * allocating swblk at the rdpi index,
- * while we dropped the object lock.
- */
- goto allocated;
+ if (sb != NULL)
+ goto allocated;
+ if (swapblk == SWAPBLK_NONE)
+ return (SWAPBLK_NONE);
+ while ((sb = uma_zalloc(swblk_zone,
+ M_NOWAIT | (curproc == pageproc ? M_USE_RESERVE : 0))) == NULL) {
+ if (nowait)
+ return (swapblk);
+ swp_pager_alloc_wait(object, swblk_zone,
+ &swblk_zone_exhausted, "blk", "swzonxb");
+ sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi);
+ if (sb != NULL)
+ /*
+ * Somebody swapped out a nearby page, allocating swblk
+ * at the rdpi index, while we dropped the object lock.
+ */
+ goto allocated;
+ }
+ sb->p = rdpi;
+ for (i = 0; i < SWAP_META_PAGES; i++)
+ sb->d[i] = SWAPBLK_NONE;
+ if (atomic_cmpset_int(&swblk_zone_exhausted, 1, 0))
+ printf("swblk zone ok\n");
+ while (SWAP_PCTRIE_INSERT(&object->un_pager.swp.swp_blks, sb) != 0) {
+ if (nowait) {
+ uma_zfree(swblk_zone, sb);
+ return (swapblk);
}
- for (;;) {
- error = SWAP_PCTRIE_INSERT(
- &object->un_pager.swp.swp_blks, sb);
- if (error == 0) {
- if (atomic_cmpset_int(&swpctrie_zone_exhausted,
- 1, 0))
- printf("swpctrie zone ok\n");
- break;
- }
- VM_OBJECT_WUNLOCK(object);
- if (uma_zone_exhausted(swpctrie_zone)) {
- if (atomic_cmpset_int(&swpctrie_zone_exhausted,
- 0, 1))
- printf("swap pctrie zone exhausted, "
- "increase kern.maxswzone\n");
- vm_pageout_oom(VM_OOM_SWAPZ);
- pause("swzonxp", 10);
- } else
- uma_zwait(swpctrie_zone);
- VM_OBJECT_WLOCK(object);
- sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
- rdpi);
- if (sb1 != NULL) {
- uma_zfree(swblk_zone, sb);
- sb = sb1;
- goto allocated;
- }
+ swp_pager_alloc_wait(object, swpctrie_zone,
+ &swpctrie_zone_exhausted, "pctrie", "swzonxp");
+ sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi);
+ if (sb1 != NULL) {
+ uma_zfree(swblk_zone, sb);
+ sb = sb1;
+ goto allocated;
}
}
+ if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1, 0))
+ printf("swpctrie zone ok\n");
+
allocated:
MPASS(sb->p == rdpi);
modpi = pindex % SWAP_META_PAGES;
/* Return prior contents of metadata. */
prev_swapblk = sb->d[modpi];
- /* Enter block into metadata. */
- sb->d[modpi] = swapblk;
+ if (!nowait || prev_swapblk == SWAPBLK_NONE) {
+ /* Enter block into metadata. */
+ sb->d[modpi] = swapblk;
+
+ /*
+ * Free the swblk if we end up with the empty page run.
+ */
+ if (swapblk == SWAPBLK_NONE)
+ swp_pager_free_empty_swblk(object, sb);
+ }
- /*
- * Free the swblk if we end up with the empty page run.
- */
- if (swapblk == SWAPBLK_NONE)
- swp_pager_free_empty_swblk(object, sb);
return (prev_swapblk);
}
@@ -2168,6 +2140,7 @@
{
struct page_range range;
struct swblk *sb;
+ daddr_t blk;
vm_page_t m;
vm_pindex_t offset, last;
vm_size_t mc;
@@ -2193,12 +2166,20 @@
limit = last - sb->p < SWAP_META_PAGES ? last - sb->p :
SWAP_META_PAGES;
for (i = start; i < limit; i++) {
- if (sb->d[i] == SWAPBLK_NONE)
+ blk = sb->d[i];
+ if (blk == SWAPBLK_NONE)
continue;
+
if (dstobject == NULL ||
- !swp_pager_xfer_source(srcobject, dstobject,
- sb->p + i - offset, sb->d[i])) {
+ (blk = swp_pager_meta_build(dstobject,
+ sb->p + i - offset, blk, true),
+ blk != sb->d[i] && blk != SWAPBLK_NONE))
swp_pager_update_freerange(&range, sb->d[i]);
+ else if (blk == sb->d[i]) {
+ VM_OBJECT_WUNLOCK(srcobject);
+ swp_pager_meta_build(dstobject,
+ sb->p + i - offset, blk, false);
+ VM_OBJECT_WLOCK(srcobject);
}
if (moved != NULL) {
if (m != NULL && m->pindex != pindex + i - 1)

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