From 8ea0b3bb2fc36b4c87fc62ea82e4ef79a6df3c9c Mon Sep 17 00:00:00 2001 From: Colin Percival Date: Sun, 26 Dec 2010 13:05:43 +0000 Subject: Lock the vm page queue mutex in pmap_pte_release around the call to PMAP_SET_VA; this fixes a mutex-not-held panic when a process which called mlock(2) exits, and parallels a change made in pmap_pte 10 months ago (svn r204160). Note: The locking in this code is utterly broken. We should not be using the VM page queue mutex to protect the queue of pending Xen page mapping hypervisor calls. Even if it made sense to do so, this commit and r204160 introduce LORs between the vm page queue mutex and PMAP2mutex. (However, a possible deadlock is better than a guaranteed panic, and this change will hopefully make life easier for whoever fixes the Xen pmap locking in the future.) PR: kern/140313 MFC after: 3 days --- sys/i386/xen/pmap.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'sys/i386/xen') diff --git a/sys/i386/xen/pmap.c b/sys/i386/xen/pmap.c index b63089dc36dc..9d72ad58d722 100644 --- a/sys/i386/xen/pmap.c +++ b/sys/i386/xen/pmap.c @@ -1015,7 +1015,9 @@ pmap_pte_release(pt_entry_t *pte) if ((pt_entry_t *)((vm_offset_t)pte & ~PAGE_MASK) == PADDR2) { CTR1(KTR_PMAP, "pmap_pte_release: pte=0x%jx", *PMAP2); + vm_page_lock_queues(); PT_SET_VA(PMAP2, 0, TRUE); + vm_page_unlock_queues(); mtx_unlock(&PMAP2mutex); } } -- cgit v1.2.3