On Fri, Dec 20, 2024 at 11:10 PM Jens Axboe <axboe@xxxxxxxxx> wrote:
>
> On 12/20/24 3:23 AM, Nilay Shroff wrote:
> > On 12/18/24 15:46, Ming Lei wrote:
> >> This reverts commit be26ba96421ab0a8fa2055ccf7db7832a13c44d2.
> >>
> >> Commit be26ba96421a ("block: Fix potential deadlock while freezing queue and
> >> acquiring sysfs_loc") actually reverts commit 22465bbac53c ("blk-mq: move cpuhp
> >> callback registering out of q->sysfs_lock"), and causes the original resctrl
> >> lockdep warning.
> >>
> >> So revert it and we need to fix the issue in another way.
> >>
> > Hi Ming,
> >
> > Can we wait here for some more time before we revert this as this is
> > currently being discussed[1] and we don't know yet how we may fix it?
> >
> > [1]https://lore.kernel.org/all/20241219061514.GA19575@xxxxxx/
>
> It's already queued up and will go out today. Doesn't exclude people
> working on solving this for real.
IMO, it is correct to cut the dependency between q->sysfs_lock and
global cpu hotplug lock, otherwise more subsystems can be involved,
so let's revert it first.
Christoph is also working on q->sysfs_lock warning, and we can try to
figure out other solutions given the involved(or most of) locks should be
from block layer internal.
https://lore.kernel.org/linux-block/20241219061514.GA19575@xxxxxx/
Thanks,
Ming
