Re: [RFC] [PATCH] Fix warning at fs/dcache.c:430 dentry_free

[Al Viro]

On Mon, Apr 06, 2026 at 09:52:16PM +0200, Helge Deller wrote:
> The debian buildd servers for the parisc architecture crash reproduceably when
> building the webkit2gtk debian package, shortly after having shown the warning
> below.
> 
> This patch keeps the lock of the dentry up until when the dentry is given back
> to the cache and after having freed the "external dentry name".
> 
> I'm not sure if this patch is really correct, but it seems to have fixed the
> problem, although more testing is needed.

Hard NAK.  You are turning every place that grabs ->d_lock on a dentry scheduled
for freeing (like, say it, any RCU pathwalk trying to check if the end result can
be grabbed) into a UAF.

Do you have a better localized reproducer?