[Bug report] hash_name() may cross page boundary and trigger sleep in RCU context

[Zizhi Wo]

在 2025/11/29 11:55, Al Viro 写道:
> On Sat, Nov 29, 2025 at 09:02:27AM +0800, Zizhi Wo wrote:
> 
>> Thank you very much for the answer. For the vmalloc area, I checked the
>> call points on the vfs side, such as dentry_string_cmp() or hash_name().
>> Their "names addr" are all assigned by kmalloc(), so there should be no
>> corresponding issues. But I'm not familiar with the other calling
>> points...
> 
> Pathname might be a symlink body, sitting in page cache or whatever
> ->get_link() has returned...
> 


Thanks for the additional explanation — I indeed hadn't considered
symlinks. But if the data is in the page cache, as I understand it, its
address wouldn't be in the vmalloc area, right? However, for other
.get_link implementations, it's true that there's no guarantee.

Thanks,
Zizhi Wo