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Code Issues Releases Activity

The vm_fault() should not be allowed to proceed on the map entry which

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is being wired now.  The entry wired count is changed to non-zero in
advance, before the map lock is dropped.  This makes the vm_fault() to
perceive the entry as wired, and breaks the fragment which moves the
wire count from the shadowed page, to the upper page, making the code
unwiring non-wired page.

On the other hand, the vm_fault() calls from vm_fault_wire() should be
allowed to proceed, so only drain MAP_ENTRY_IN_TRANSITION from
vm_fault() when wiring_thread is not current.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2013-07-11 05:58:28 +00:00
parent 0acea7dfde
commit 4f9c9114a3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=253191
1 changed files with 13 additions and 0 deletions
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13
sys/vm/vm_fault.c
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@ -280,6 +280,19 @@ RetryFault:;
(u_long)vaddr);
}
if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION &&
fs.entry->wiring_thread != curthread) {
vm_map_unlock_read(fs.map);
vm_map_lock(fs.map);
if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) &&
(fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
vm_map_unlock_and_wait(fs.map, 0);
} else
vm_map_unlock(fs.map);
goto RetryFault;
}
/*
* Make a reference to this object to prevent its disposal while we
* are messing with it. Once we have the reference, the map is free