Re: [PATCH v3] eventpoll: Fix priority inversion problem

[Nam Cao]

On Wed, Jun 25, 2025 at 05:57:18PM +0200, Nam Cao wrote:
> On Wed, Jun 25, 2025 at 05:33:54PM +0200, Sebastian Andrzej Siewior wrote:
> > On 2025-06-25 17:27:02 [+0200], Nam Cao wrote:
> > > To be sure, I tried your suggestion. Systemd sometimes failed to boot, and
> > > my stress test crashed instantly.
> > 
> > I had a trace_printk() there while testing and it never triggered.
> 
> This code path is only executed for broken userspace.

Forgot to mention, my test crashed because the __llist_add(n, &txlist)
below doesn't care if 'n' is already in a list. By changing to from
llist_del_first() to llist_del_first_init(), it is possible for 'n' to be
in a list, therefore __llist_add() would break.

Nam