On Fri, 2023-11-24 at 17:46 +0000, Greg Kroah-Hartman wrote: > 6.5-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Juergen Gross <jgross@xxxxxxxx> > > [ Upstream commit e64e7c74b99ec9e439abca75f522f4b98f220bd1 ] > > xen_send_IPI_one() is being used by cpuhp_report_idle_dead() after > it calls rcu_report_dead(), meaning that any RCU usage by > xen_send_IPI_one() is a bad idea. > > Unfortunately xen_send_IPI_one() is using notify_remote_via_irq() > today, which is using irq_get_chip_data() via info_for_irq(). And > irq_get_chip_data() in turn is using a maple-tree lookup requiring > RCU. > > Avoid this problem by caching the ipi event channels in another > percpu variable, allowing the use notify_remote_via_evtchn() in > xen_send_IPI_one(). IIRC, the result of this bug is a mostly harmless lockdep splat. On the other hand, the result of *fixing* this bug is that lockdep doesn't whine, and lockdep keeps working. Only to later trigger a warning really early during cpu hotplug, causing the whole machine to go down with a triple-fault. Can we have the backport of https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/commit/?h=linux-next&id=9bb69ba4c177dccaa1f5b5cbdf80b67813328348 *first* and then this one?
Attachment:
smime.p7s
Description: S/MIME cryptographic signature
