diff options
Diffstat (limited to 'sys/vm/vm_page.c')
| -rw-r--r-- | sys/vm/vm_page.c | 34 |
1 files changed, 32 insertions, 2 deletions
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c index 21c7080..8e0c8bb 100644 --- a/sys/vm/vm_page.c +++ b/sys/vm/vm_page.c @@ -729,7 +729,12 @@ vm_page_sleep(vm_page_t m, const char *msg) /* * vm_page_dirty: * - * make page all dirty + * Set all bits in the page's dirty field. + * + * The object containing the specified page must be locked if the call is + * made from the machine-independent layer. If, however, the call is + * made from the pmap layer, then the page queues lock may be required. + * See vm_page_clear_dirty_mask(). */ void vm_page_dirty(vm_page_t m) @@ -2325,15 +2330,40 @@ vm_page_clear_dirty_mask(vm_page_t m, int pagebits) /* * If the object is locked and the page is neither VPO_BUSY nor * PG_WRITEABLE, then the page's dirty field cannot possibly be - * modified by a concurrent pmap operation. + * set by a concurrent pmap operation. */ VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); if ((m->oflags & VPO_BUSY) == 0 && (m->flags & PG_WRITEABLE) == 0) m->dirty &= ~pagebits; else { +#if defined(__amd64__) || defined(__i386__) || defined(__ia64__) + /* + * On the aforementioned architectures, the page queues lock + * is not required by the following read-modify-write + * operation. The combination of the object's lock and an + * atomic operation suffice. Moreover, the pmap layer on + * these architectures can call vm_page_dirty() without + * holding the page queues lock. + */ +#if PAGE_SIZE == 4096 + atomic_clear_char(&m->dirty, pagebits); +#elif PAGE_SIZE == 8192 + atomic_clear_short(&m->dirty, pagebits); +#elif PAGE_SIZE == 16384 + atomic_clear_int(&m->dirty, pagebits); +#else +#error "PAGE_SIZE is not supported." +#endif +#else + /* + * Otherwise, the page queues lock is required to ensure that + * a concurrent pmap operation does not set the page's dirty + * field during the following read-modify-write operation. + */ vm_page_lock_queues(); m->dirty &= ~pagebits; vm_page_unlock_queues(); +#endif } } |
