svn commit: r263328 - in head/sys: dev/md vm
Attilio Rao
attilio at FreeBSD.org
Wed Mar 19 01:13:43 UTC 2014
Author: attilio
Date: Wed Mar 19 01:13:42 2014
New Revision: 263328
URL: http://svnweb.freebsd.org/changeset/base/263328
Log:
vm_page_grab() and vm_pager_get_pages() can drop the vm_object lock,
then threads can sleep on the pip condition.
Avoid to deadlock such threads by correctly awakening the sleeping ones
after the pip is finished.
swapoff side of the bug can likely result in shutdown deadlocks.
Sponsored by: EMC / Isilon Storage Division
Reported by: pho, pluknet
Tested by: pho
Modified:
head/sys/dev/md/md.c
head/sys/vm/swap_pager.c
Modified: head/sys/dev/md/md.c
==============================================================================
--- head/sys/dev/md/md.c Wed Mar 19 00:55:12 2014 (r263327)
+++ head/sys/dev/md/md.c Wed Mar 19 01:13:42 2014 (r263328)
@@ -903,7 +903,7 @@ mdstart_swap(struct md_s *sc, struct bio
offs = 0;
ma_offs += len;
}
- vm_object_pip_subtract(sc->object, 1);
+ vm_object_pip_wakeup(sc->object);
VM_OBJECT_WUNLOCK(sc->object);
return (rv != VM_PAGER_ERROR ? 0 : ENOSPC);
}
Modified: head/sys/vm/swap_pager.c
==============================================================================
--- head/sys/vm/swap_pager.c Wed Mar 19 00:55:12 2014 (r263327)
+++ head/sys/vm/swap_pager.c Wed Mar 19 01:13:42 2014 (r263328)
@@ -1713,7 +1713,7 @@ swp_pager_force_pagein(vm_object_t objec
vm_object_pip_add(object, 1);
m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
if (m->valid == VM_PAGE_BITS_ALL) {
- vm_object_pip_subtract(object, 1);
+ vm_object_pip_wakeup(object);
vm_page_dirty(m);
vm_page_lock(m);
vm_page_activate(m);
@@ -1725,7 +1725,7 @@ swp_pager_force_pagein(vm_object_t objec
if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK)
panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
- vm_object_pip_subtract(object, 1);
+ vm_object_pip_wakeup(object);
vm_page_dirty(m);
vm_page_lock(m);
vm_page_deactivate(m);
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