svn commit: r269134 - head/sys/vm
hiren panchasara
hiren at freebsd.org
Thu Aug 28 16:52:53 UTC 2014
On Thu, Aug 28, 2014 at 9:30 AM, Alan Cox <alc at rice.edu> wrote:
>
> On Aug 28, 2014, at 3:30 AM, Adrian Chadd wrote:
>
>> Hi Alan!
>>
>> I just reverted back to the commit before this one and it fixed my MIPS32 boot.
>>
>> Would you have some time to help me help you figure out why things broke? :)
>>
>
>
> Have you tried booting a kernel based on r269134? At the time, I tested a 64-bit MIPS kernel on gxemul, and it ran ok. Also, Hiren reports that a 32-bit kernel from about two weeks after r269134 works for him.
>
To be precise, I am on r269799 which works for me.
cheers,
Hiren
>
>>
>>
>>
>>
>> -a
>>
>>
>> On 26 July 2014 11:10, Alan Cox <alc at freebsd.org> wrote:
>>> Author: alc
>>> Date: Sat Jul 26 18:10:18 2014
>>> New Revision: 269134
>>> URL: http://svnweb.freebsd.org/changeset/base/269134
>>>
>>> Log:
>>> When unwiring a region of an address space, do not assume that the
>>> underlying physical pages are mapped by the pmap. If, for example, the
>>> application has performed an mprotect(..., PROT_NONE) on any part of the
>>> wired region, then those pages will no longer be mapped by the pmap.
>>> So, using the pmap to lookup the wired pages in order to unwire them
>>> doesn't always work, and when it doesn't work wired pages are leaked.
>>>
>>> To avoid the leak, introduce and use a new function vm_object_unwire()
>>> that locates the wired pages by traversing the object and its backing
>>> objects.
>>>
>>> At the same time, switch from using pmap_change_wiring() to the recently
>>> introduced function pmap_unwire() for unwiring the region's mappings.
>>> pmap_unwire() is faster, because it operates a range of virtual addresses
>>> rather than a single virtual page at a time. Moreover, by operating on
>>> a range, it is superpage friendly. It doesn't waste time performing
>>> unnecessary demotions.
>>>
>>> Reported by: markj
>>> Reviewed by: kib
>>> Tested by: pho, jmg (arm)
>>> Sponsored by: EMC / Isilon Storage Division
>>>
>>> Modified:
>>> head/sys/vm/vm_extern.h
>>> head/sys/vm/vm_fault.c
>>> head/sys/vm/vm_map.c
>>> head/sys/vm/vm_object.c
>>> head/sys/vm/vm_object.h
>>>
>>> Modified: head/sys/vm/vm_extern.h
>>> ==============================================================================
>>> --- head/sys/vm/vm_extern.h Sat Jul 26 17:59:25 2014 (r269133)
>>> +++ head/sys/vm/vm_extern.h Sat Jul 26 18:10:18 2014 (r269134)
>>> @@ -81,7 +81,6 @@ int vm_fault_hold(vm_map_t map, vm_offse
>>> int fault_flags, vm_page_t *m_hold);
>>> int vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
>>> vm_prot_t prot, vm_page_t *ma, int max_count);
>>> -void vm_fault_unwire(vm_map_t, vm_offset_t, vm_offset_t, boolean_t);
>>> int vm_fault_wire(vm_map_t, vm_offset_t, vm_offset_t, boolean_t);
>>> int vm_forkproc(struct thread *, struct proc *, struct thread *, struct vmspace *, int);
>>> void vm_waitproc(struct proc *);
>>>
>>> Modified: head/sys/vm/vm_fault.c
>>> ==============================================================================
>>> --- head/sys/vm/vm_fault.c Sat Jul 26 17:59:25 2014 (r269133)
>>> +++ head/sys/vm/vm_fault.c Sat Jul 26 18:10:18 2014 (r269134)
>>> @@ -106,6 +106,7 @@ __FBSDID("$FreeBSD$");
>>> #define PFFOR 4
>>>
>>> static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *);
>>> +static void vm_fault_unwire(vm_map_t, vm_offset_t, vm_offset_t, boolean_t);
>>>
>>> #define VM_FAULT_READ_BEHIND 8
>>> #define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX)
>>> @@ -1186,7 +1187,7 @@ vm_fault_wire(vm_map_t map, vm_offset_t
>>> *
>>> * Unwire a range of virtual addresses in a map.
>>> */
>>> -void
>>> +static void
>>> vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
>>> boolean_t fictitious)
>>> {
>>>
>>> Modified: head/sys/vm/vm_map.c
>>> ==============================================================================
>>> --- head/sys/vm/vm_map.c Sat Jul 26 17:59:25 2014 (r269133)
>>> +++ head/sys/vm/vm_map.c Sat Jul 26 18:10:18 2014 (r269134)
>>> @@ -132,6 +132,7 @@ static void _vm_map_init(vm_map_t map, p
>>> vm_offset_t max);
>>> static void vm_map_entry_deallocate(vm_map_entry_t entry, boolean_t system_map);
>>> static void vm_map_entry_dispose(vm_map_t map, vm_map_entry_t entry);
>>> +static void vm_map_entry_unwire(vm_map_t map, vm_map_entry_t entry);
>>> #ifdef INVARIANTS
>>> static void vm_map_zdtor(void *mem, int size, void *arg);
>>> static void vmspace_zdtor(void *mem, int size, void *arg);
>>> @@ -2393,16 +2394,10 @@ done:
>>> (entry->eflags & MAP_ENTRY_USER_WIRED))) {
>>> if (user_unwire)
>>> entry->eflags &= ~MAP_ENTRY_USER_WIRED;
>>> - entry->wired_count--;
>>> - if (entry->wired_count == 0) {
>>> - /*
>>> - * Retain the map lock.
>>> - */
>>> - vm_fault_unwire(map, entry->start, entry->end,
>>> - entry->object.vm_object != NULL &&
>>> - (entry->object.vm_object->flags &
>>> - OBJ_FICTITIOUS) != 0);
>>> - }
>>> + if (entry->wired_count == 1)
>>> + vm_map_entry_unwire(map, entry);
>>> + else
>>> + entry->wired_count--;
>>> }
>>> KASSERT((entry->eflags & MAP_ENTRY_IN_TRANSITION) != 0,
>>> ("vm_map_unwire: in-transition flag missing %p", entry));
>>> @@ -2635,19 +2630,12 @@ done:
>>> * unnecessary.
>>> */
>>> entry->wired_count = 0;
>>> - } else {
>>> - if (!user_wire ||
>>> - (entry->eflags & MAP_ENTRY_USER_WIRED) == 0)
>>> + } else if (!user_wire ||
>>> + (entry->eflags & MAP_ENTRY_USER_WIRED) == 0) {
>>> + if (entry->wired_count == 1)
>>> + vm_map_entry_unwire(map, entry);
>>> + else
>>> entry->wired_count--;
>>> - if (entry->wired_count == 0) {
>>> - /*
>>> - * Retain the map lock.
>>> - */
>>> - vm_fault_unwire(map, entry->start, entry->end,
>>> - entry->object.vm_object != NULL &&
>>> - (entry->object.vm_object->flags &
>>> - OBJ_FICTITIOUS) != 0);
>>> - }
>>> }
>>> next_entry_done:
>>> KASSERT((entry->eflags & MAP_ENTRY_IN_TRANSITION) != 0,
>>> @@ -2783,9 +2771,13 @@ vm_map_sync(
>>> static void
>>> vm_map_entry_unwire(vm_map_t map, vm_map_entry_t entry)
>>> {
>>> - vm_fault_unwire(map, entry->start, entry->end,
>>> - entry->object.vm_object != NULL &&
>>> - (entry->object.vm_object->flags & OBJ_FICTITIOUS) != 0);
>>> +
>>> + VM_MAP_ASSERT_LOCKED(map);
>>> + KASSERT(entry->wired_count > 0,
>>> + ("vm_map_entry_unwire: entry %p isn't wired", entry));
>>> + pmap_unwire(map->pmap, entry->start, entry->end);
>>> + vm_object_unwire(entry->object.vm_object, entry->offset, entry->end -
>>> + entry->start, PQ_ACTIVE);
>>> entry->wired_count = 0;
>>> }
>>>
>>>
>>> Modified: head/sys/vm/vm_object.c
>>> ==============================================================================
>>> --- head/sys/vm/vm_object.c Sat Jul 26 17:59:25 2014 (r269133)
>>> +++ head/sys/vm/vm_object.c Sat Jul 26 18:10:18 2014 (r269134)
>>> @@ -2202,6 +2202,78 @@ vm_object_set_writeable_dirty(vm_object_
>>> vm_object_set_flag(object, OBJ_MIGHTBEDIRTY);
>>> }
>>>
>>> +/*
>>> + * vm_object_unwire:
>>> + *
>>> + * For each page offset within the specified range of the given object,
>>> + * find the highest-level page in the shadow chain and unwire it. A page
>>> + * must exist at every page offset, and the highest-level page must be
>>> + * wired.
>>> + */
>>> +void
>>> +vm_object_unwire(vm_object_t object, vm_ooffset_t offset, vm_size_t length,
>>> + uint8_t queue)
>>> +{
>>> + vm_object_t tobject;
>>> + vm_page_t m, tm;
>>> + vm_pindex_t end_pindex, pindex, tpindex;
>>> + int depth, locked_depth;
>>> +
>>> + KASSERT((offset & PAGE_MASK) == 0,
>>> + ("vm_object_unwire: offset is not page aligned"));
>>> + KASSERT((length & PAGE_MASK) == 0,
>>> + ("vm_object_unwire: length is not a multiple of PAGE_SIZE"));
>>> + /* The wired count of a fictitious page never changes. */
>>> + if ((object->flags & OBJ_FICTITIOUS) != 0)
>>> + return;
>>> + pindex = OFF_TO_IDX(offset);
>>> + end_pindex = pindex + atop(length);
>>> + locked_depth = 1;
>>> + VM_OBJECT_RLOCK(object);
>>> + m = vm_page_find_least(object, pindex);
>>> + while (pindex < end_pindex) {
>>> + if (m == NULL || pindex < m->pindex) {
>>> + /*
>>> + * The first object in the shadow chain doesn't
>>> + * contain a page at the current index. Therefore,
>>> + * the page must exist in a backing object.
>>> + */
>>> + tobject = object;
>>> + tpindex = pindex;
>>> + depth = 0;
>>> + do {
>>> + tpindex +=
>>> + OFF_TO_IDX(tobject->backing_object_offset);
>>> + tobject = tobject->backing_object;
>>> + KASSERT(tobject != NULL,
>>> + ("vm_object_unwire: missing page"));
>>> + if ((tobject->flags & OBJ_FICTITIOUS) != 0)
>>> + goto next_page;
>>> + depth++;
>>> + if (depth == locked_depth) {
>>> + locked_depth++;
>>> + VM_OBJECT_RLOCK(tobject);
>>> + }
>>> + } while ((tm = vm_page_lookup(tobject, tpindex)) ==
>>> + NULL);
>>> + } else {
>>> + tm = m;
>>> + m = TAILQ_NEXT(m, listq);
>>> + }
>>> + vm_page_lock(tm);
>>> + vm_page_unwire(tm, queue);
>>> + vm_page_unlock(tm);
>>> +next_page:
>>> + pindex++;
>>> + }
>>> + /* Release the accumulated object locks. */
>>> + for (depth = 0; depth < locked_depth; depth++) {
>>> + tobject = object->backing_object;
>>> + VM_OBJECT_RUNLOCK(object);
>>> + object = tobject;
>>> + }
>>> +}
>>> +
>>> #include "opt_ddb.h"
>>> #ifdef DDB
>>> #include <sys/kernel.h>
>>>
>>> Modified: head/sys/vm/vm_object.h
>>> ==============================================================================
>>> --- head/sys/vm/vm_object.h Sat Jul 26 17:59:25 2014 (r269133)
>>> +++ head/sys/vm/vm_object.h Sat Jul 26 18:10:18 2014 (r269134)
>>> @@ -291,6 +291,8 @@ void vm_object_shadow (vm_object_t *, vm
>>> void vm_object_split(vm_map_entry_t);
>>> boolean_t vm_object_sync(vm_object_t, vm_ooffset_t, vm_size_t, boolean_t,
>>> boolean_t);
>>> +void vm_object_unwire(vm_object_t object, vm_ooffset_t offset,
>>> + vm_size_t length, uint8_t queue);
>>> #endif /* _KERNEL */
>>>
>>> #endif /* _VM_OBJECT_ */
>>>
>>
>
>
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