else
mem_cgroup_uncharge_page(new_page);
if (new_page)
page_cache_release(new_page);
if (old_page)
page_cache_release(old_page);
unlock:
pte_unmap_unlock(page_table, ptl);
if (dirty_page) {
/*
* Yes, Virginia, this is actually required to prevent a race
* with clear_page_dirty_for_io() from clearing the page dirty
* bit after it clear all dirty ptes, but before a racing
* do_wp_page installs a dirty pte.
*
* do_no_page is protected similarly.
*/
if (!page_mkwrite) {
wait_on_page_locked(dirty_page);
set_page_dirty_balance(dirty_page, page_mkwrite);
}
put_page(dirty_page);
if (page_mkwrite) {
struct address_space *mapping = dirty_page->mapping;
set_page_dirty(dirty_page);
unlock_page(dirty_page);
page_cache_release(dirty_page);
if (mapping) {
/*
* Some device drivers do not set page.mapping
* but still dirty their pages
*/
balance_dirty_pages_ratelimited(mapping);
}
}
/* file_update_time outside page_lock */
if (vma->vm_file)
file_update_time(vma->vm_file);
}
return ret;
oom_free_new:
page_cache_release(new_page);
oom:
if (old_page) {
if (page_mkwrite) {
unlock_page(old_page);
page_cache_release(old_page);
}
page_cache_release(old_page);
}
return VM_FAULT_OOM;
unwritable_page:
page_cache_release(old_page);
return ret;
}
一级一级返回，最终返回到函数__do_page_fault，会根据返回值fault累计task的相应异常类型次数(maj_flt或min_flt)，并最终把fault返回给函数do_page_fault，释放信号量mmap_sem，正常情况下就返回0，缺页异常处理完毕。 |
