On 5/24/24 12:32 AM, Thomas Gleixner wrote: > On Thu, May 23 2024 at 23:03, Vlastimil Babka wrote: >> On 5/23/24 12:36 PM, Thomas Gleixner wrote: >>>> ------------[ cut here ]------------ >>>> DEBUG_LOCKS_WARN_ON(l->owner) >>>> WARNING: CPU: 3 PID: 5221 at include/linux/local_lock_internal.h:30 local_lock_acquire include/linux/local_lock_internal.h:30 [inline] >>>> WARNING: CPU: 3 PID: 5221 at include/linux/local_lock_internal.h:30 flush_slab mm/slub.c:3088 [inline] >>>> WARNING: CPU: 3 PID: 5221 at include/linux/local_lock_internal.h:30 flush_cpu_slab+0x37f/0x410 mm/slub.c:3146 >> >> I'm puzzled by this. We use local_lock_irqsave() on !PREEMPT_RT everywhere. >> IIUC this warning says we did the irqsave() and then found out somebody else >> already set the owner? But that means they also did that irqsave() and set >> themselves as l->owner. Does that mey there would be a spurious irq enable >> that didn't go through local_unlock_irqrestore()? >> >> Also this particular stack is from the work, which is scheduled by >> queue_work_on() in flush_all_cpus_locked(), which also has a >> lockdep_assert_cpus_held() so it should fullfill the "the caller must ensure >> the cpu doesn't go away" property. But I think even if this ended up on the >> wrong cpu (for the full duration or migrated while processing the work item) >> somehow, it wouldn't be able to cause such warning, but rather corrupt >> something else > > Indeed. There is another report which makes no sense either: > > https://lore.kernel.org/lkml/000000000000fa09d906191c3ee5@xxxxxxxxxx That looks like slab->next which should contain a valid pointer or NULL, contains 0x13. slab->next is initialized in put_cpu_partial() from s->cpu_slab->partial Here we have corruption inside s->cpu_slab->list_lock > Both look like data corropution issues caused by whatever... s->cpu_slab is percpu allocation so possibly another percpu alloc user has a buffer overflow? > Thanks, > > tglx
