struct address_space *page_mapping(struct page *page)
{
- unsigned long mapping;
+ struct address_space *mapping;
+
+ page = compound_head(page);
/* This happens if someone calls flush_dcache_page on slab page */
if (unlikely(PageSlab(page)))
return swap_address_space(entry);
}
- mapping = (unsigned long)page->mapping;
- if (mapping & PAGE_MAPPING_FLAGS)
+ mapping = page->mapping;
+ if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
return NULL;
- return page->mapping;
+ return mapping;
+}
+
+/* Slow path of page_mapcount() for compound pages */
+int __page_mapcount(struct page *page)
+{
+ int ret;
+
+ ret = atomic_read(&page->_mapcount) + 1;
+ page = compound_head(page);
+ ret += atomic_read(compound_mapcount_ptr(page)) + 1;
+ if (PageDoubleMap(page))
+ ret--;
+ return ret;
}
+EXPORT_SYMBOL_GPL(__page_mapcount);
int overcommit_ratio_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
int res = 0;
unsigned int len;
struct mm_struct *mm = get_task_mm(task);
+ unsigned long arg_start, arg_end, env_start, env_end;
if (!mm)
goto out;
if (!mm->arg_end)
goto out_mm; /* Shh! No looking before we're done */
- len = mm->arg_end - mm->arg_start;
+ down_read(&mm->mmap_sem);
+ arg_start = mm->arg_start;
+ arg_end = mm->arg_end;
+ env_start = mm->env_start;
+ env_end = mm->env_end;
+ up_read(&mm->mmap_sem);
+
+ len = arg_end - arg_start;
if (len > buflen)
len = buflen;
- res = access_process_vm(task, mm->arg_start, buffer, len, 0);
+ res = access_process_vm(task, arg_start, buffer, len, 0);
/*
* If the nul at the end of args has been overwritten, then
if (len < res) {
res = len;
} else {
- len = mm->env_end - mm->env_start;
+ len = env_end - env_start;
if (len > buflen - res)
len = buflen - res;
- res += access_process_vm(task, mm->env_start,
+ res += access_process_vm(task, env_start,
buffer+res, len, 0);
res = strnlen(buffer, res);
}