Author: kib
Date: Wed Sep 14 10:51:06 2016
New Revision: 305803
URL: https://svnweb.freebsd.org/changeset/base/305803
Log:
MFC r305129:
Make swapoff reliable.
Modified:
stable/10/sys/vm/swap_pager.c
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/vm/swap_pager.c
==============================================================================
--- stable/10/sys/vm/swap_pager.c Wed Sep 14 10:36:44 2016
(r305802)
+++ stable/10/sys/vm/swap_pager.c Wed Sep 14 10:51:06 2016
(r305803)
@@ -1764,36 +1764,49 @@ static void
swap_pager_swapoff(struct swdevt *sp)
{
struct swblock *swap;
+ vm_object_t locked_obj, object;
+ vm_pindex_t pindex;
int i, j, retries;
GIANT_REQUIRED;
retries = 0;
+ locked_obj = NULL;
full_rescan:
mtx_lock(&swhash_mtx);
for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */
restart:
for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) {
- vm_object_t object = swap->swb_object;
- vm_pindex_t pindex = swap->swb_index;
+ object = swap->swb_object;
+ pindex = swap->swb_index;
for (j = 0; j < SWAP_META_PAGES; ++j) {
- if (swp_pager_isondev(swap->swb_pages[j], sp)) {
- /* avoid deadlock */
+ if (!swp_pager_isondev(swap->swb_pages[j], sp))
+ continue;
+ if (locked_obj != object) {
+ if (locked_obj != NULL)
+ VM_OBJECT_WUNLOCK(locked_obj);
+ locked_obj = object;
if (!VM_OBJECT_TRYWLOCK(object)) {
- break;
- } else {
mtx_unlock(&swhash_mtx);
- swp_pager_force_pagein(object,
- pindex + j);
- VM_OBJECT_WUNLOCK(object);
+ /* Depends on type-stability. */
+ VM_OBJECT_WLOCK(object);
mtx_lock(&swhash_mtx);
goto restart;
}
}
+ MPASS(locked_obj == object);
+ mtx_unlock(&swhash_mtx);
+ swp_pager_force_pagein(object, pindex + j);
+ mtx_lock(&swhash_mtx);
+ goto restart;
}
}
}
mtx_unlock(&swhash_mtx);
+ if (locked_obj != NULL) {
+ VM_OBJECT_WUNLOCK(locked_obj);
+ locked_obj = NULL;
+ }
if (sp->sw_used) {
/*
* Objects may be locked or paging to the device being
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