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59677d3c0e
First, a file is mmap(2)ed and then mlock(2)ed. Later, it is truncated. Under "normal" circumstances, i.e., when the file is not mlock(2)ed, the pages beyond the EOF are unmapped and freed. However, when the file is mlock(2)ed, the pages beyond the EOF are unmapped but not freed because they have a non-zero wire count. This can be a mistake. Specifically, it is a mistake if the sole reason why the pages are wired is because of wired, managed mappings. Previously, unmapping the pages destroys these wired, managed mappings, but does not reduce the pages' wire count. Consequently, when the file is unmapped, the pages are not unwired because the wired mapping has been destroyed. Moreover, when the vm object is finally destroyed, the pages are leaked because they are still wired. The fix is to reduce the pages' wired count by the number of wired, managed mappings destroyed. To do this, I introduce a new pmap function pmap_page_wired_mappings() that returns the number of managed mappings to the given physical page that are wired, and I use this function in vm_object_page_remove(). Reviewed by: tegge MFC after: 6 weeks
140 lines
5.5 KiB
C
140 lines
5.5 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)pmap.h 8.1 (Berkeley) 6/11/93
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Author: Avadis Tevanian, Jr.
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*
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* $FreeBSD$
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*/
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/*
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* Machine address mapping definitions -- machine-independent
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* section. [For machine-dependent section, see "machine/pmap.h".]
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*/
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#ifndef _PMAP_VM_
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#define _PMAP_VM_
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/*
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* Each machine dependent implementation is expected to
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* keep certain statistics. They may do this anyway they
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* so choose, but are expected to return the statistics
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* in the following structure.
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*/
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struct pmap_statistics {
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long resident_count; /* # of pages mapped (total) */
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long wired_count; /* # of pages wired */
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};
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typedef struct pmap_statistics *pmap_statistics_t;
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#include <machine/pmap.h>
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#ifdef _KERNEL
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struct proc;
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struct thread;
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/*
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* Updates to kernel_vm_end are synchronized by the kernel_map's system mutex.
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*/
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extern vm_offset_t kernel_vm_end;
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void pmap_change_wiring(pmap_t, vm_offset_t, boolean_t);
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void pmap_clear_modify(vm_page_t m);
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void pmap_clear_reference(vm_page_t m);
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void pmap_copy(pmap_t, pmap_t, vm_offset_t, vm_size_t, vm_offset_t);
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void pmap_copy_page(vm_page_t, vm_page_t);
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void pmap_enter(pmap_t, vm_offset_t, vm_page_t, vm_prot_t,
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boolean_t);
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void pmap_enter_quick(pmap_t pmap, vm_offset_t va, vm_page_t m,
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vm_prot_t prot);
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void pmap_enter_object(pmap_t pmap, vm_offset_t start,
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vm_offset_t end, vm_page_t m_start, vm_prot_t prot);
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vm_paddr_t pmap_extract(pmap_t pmap, vm_offset_t va);
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vm_page_t pmap_extract_and_hold(pmap_t pmap, vm_offset_t va,
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vm_prot_t prot);
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void pmap_growkernel(vm_offset_t);
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void pmap_init(void);
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boolean_t pmap_is_modified(vm_page_t m);
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boolean_t pmap_is_prefaultable(pmap_t pmap, vm_offset_t va);
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boolean_t pmap_ts_referenced(vm_page_t m);
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vm_offset_t pmap_map(vm_offset_t *, vm_paddr_t, vm_paddr_t, int);
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void pmap_object_init_pt(pmap_t pmap, vm_offset_t addr,
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vm_object_t object, vm_pindex_t pindex, vm_size_t size);
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boolean_t pmap_page_exists_quick(pmap_t pmap, vm_page_t m);
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void pmap_page_init(vm_page_t m);
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int pmap_page_wired_mappings(vm_page_t m);
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int pmap_pinit(pmap_t);
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void pmap_pinit0(pmap_t);
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void pmap_protect(pmap_t, vm_offset_t, vm_offset_t, vm_prot_t);
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void pmap_qenter(vm_offset_t, vm_page_t *, int);
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void pmap_qremove(vm_offset_t, int);
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void pmap_release(pmap_t);
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void pmap_remove(pmap_t, vm_offset_t, vm_offset_t);
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void pmap_remove_all(vm_page_t m);
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void pmap_remove_pages(pmap_t);
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void pmap_remove_write(vm_page_t m);
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void pmap_zero_page(vm_page_t);
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void pmap_zero_page_area(vm_page_t, int off, int size);
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void pmap_zero_page_idle(vm_page_t);
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int pmap_mincore(pmap_t pmap, vm_offset_t addr);
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void pmap_activate(struct thread *td);
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vm_offset_t pmap_addr_hint(vm_object_t obj, vm_offset_t addr, vm_size_t size);
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#define pmap_resident_count(pm) ((pm)->pm_stats.resident_count)
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#define pmap_wired_count(pm) ((pm)->pm_stats.wired_count)
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#endif /* _KERNEL */
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#endif /* _PMAP_VM_ */
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