Re: [PATCH] eventfs: Initialise ei->children before it can be freed

[David CARLIER]

ah forgot to check, fair :)

Cheers.

On Tue, 25 Aug 2026 at 23:28, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Tue, 25 Aug 2026 22:57:18 +0100
> David Carlier <devnexen@xxxxxxxxx> wrote:
>
> > eventfs_create_events_dir() runs INIT_LIST_HEAD(&ei->children) only after
> > tracefs_get_inode() succeeds, but that call's failure path jumps to "fail",
> > which calls cleanup_ei() and then free_ei(). free_ei() reads the list with
> > WARN_ON_ONCE(!list_empty(&ei->children)), and alloc_root_ei() uses
> > kzalloc(), so children.next is NULL there and the WARN fires.
> >
> > The path is reachable at runtime: mkdir /sys/kernel/tracing/instances/foo
> > ends up in create_event_toplevel_files() and eventfs_create_events_dir().
> >
> > Move both INIT_LIST_HEAD() calls up to right after the allocation.
> >
> > Fixes: f0ece16ffca7 ("eventfs: Use children field for rcu head and add memory barriers")
> > Signed-off-by: David Carlier <devnexen@xxxxxxxxx>
>
> Already queued by someone else.
>
> https://patch.msgid.link/20260824144653.54044-1-kartikey406@xxxxxxxxx
>
> -- Steve