On 2/7/23 15:16, Thomas Gleixner wrote: > The memory allocators are available during early boot even in the phase > where interrupts are disabled and scheduling is not yet possible. > > The setup is so that GFP_KERNEL allocations work in this phase without > causing might_alloc() splats to be emitted because the system state is > SYSTEM_BOOTING at that point which prevents the warnings to trigger. > > Most allocation/free functions use local_irq_save()/restore() or a lock > variant of that. But kmem_cache_alloc_bulk() and kmem_cache_free_bulk() use > local_[lock]_irq_disable()/enable(), which leads to a lockdep warning when > interrupts are enabled during the early boot phase. > > This went unnoticed so far as there are no early users of these > interfaces. The upcoming conversion of the interrupt descriptor store from > radix_tree to maple_tree triggered this warning as maple_tree uses the bulk > interface. > > Cure this by moving the kmem_cache_alloc/free() bulk variants of SLUB and > SLAB to local[_lock]_irq_save()/restore(). > > There is obviously no reclaim possible and required at this point so there > is no need to expand this coverage further. > > No functional change. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> +Cc rest of slab folks Thanks, added to slab/for-6.3/fixes > --- > Initial version: https://lore.kernel.org/r/87o7qdzfay.ffs@tglx > Changes: Update SLAB as well and add changelog > --- > mm/slab.c | 18 ++++++++++-------- > mm/slub.c | 9 +++++---- > 2 files changed, 15 insertions(+), 12 deletions(-) > > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -3479,14 +3479,15 @@ cache_alloc_debugcheck_after_bulk(struct > int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, > void **p) > { > - size_t i; > struct obj_cgroup *objcg = NULL; > + unsigned long irqflags; > + size_t i; > > s = slab_pre_alloc_hook(s, NULL, &objcg, size, flags); > if (!s) > return 0; > > - local_irq_disable(); > + local_irq_save(irqflags); > for (i = 0; i < size; i++) { > void *objp = kfence_alloc(s, s->object_size, flags) ?: > __do_cache_alloc(s, flags, NUMA_NO_NODE); > @@ -3495,7 +3496,7 @@ int kmem_cache_alloc_bulk(struct kmem_ca > goto error; > p[i] = objp; > } > - local_irq_enable(); > + local_irq_restore(irqflags); > > cache_alloc_debugcheck_after_bulk(s, flags, size, p, _RET_IP_); > > @@ -3508,7 +3509,7 @@ int kmem_cache_alloc_bulk(struct kmem_ca > /* FIXME: Trace call missing. Christoph would like a bulk variant */ > return size; > error: > - local_irq_enable(); > + local_irq_restore(irqflags); > cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_); > slab_post_alloc_hook(s, objcg, flags, i, p, false, s->object_size); > kmem_cache_free_bulk(s, i, p); > @@ -3610,8 +3611,9 @@ EXPORT_SYMBOL(kmem_cache_free); > > void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p) > { > + unsigned long flags; > > - local_irq_disable(); > + local_irq_save(flags); > for (int i = 0; i < size; i++) { > void *objp = p[i]; > struct kmem_cache *s; > @@ -3621,9 +3623,9 @@ void kmem_cache_free_bulk(struct kmem_ca > > /* called via kfree_bulk */ > if (!folio_test_slab(folio)) { > - local_irq_enable(); > + local_irq_restore(flags); > free_large_kmalloc(folio, objp); > - local_irq_disable(); > + local_irq_save(flags); > continue; > } > s = folio_slab(folio)->slab_cache; > @@ -3640,7 +3642,7 @@ void kmem_cache_free_bulk(struct kmem_ca > > __cache_free(s, objp, _RET_IP_); > } > - local_irq_enable(); > + local_irq_restore(flags); > > /* FIXME: add tracing */ > } > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3913,6 +3913,7 @@ static inline int __kmem_cache_alloc_bul > size_t size, void **p, struct obj_cgroup *objcg) > { > struct kmem_cache_cpu *c; > + unsigned long irqflags; > int i; > > /* > @@ -3921,7 +3922,7 @@ static inline int __kmem_cache_alloc_bul > * handlers invoking normal fastpath. > */ > c = slub_get_cpu_ptr(s->cpu_slab); > - local_lock_irq(&s->cpu_slab->lock); > + local_lock_irqsave(&s->cpu_slab->lock, irqflags); > > for (i = 0; i < size; i++) { > void *object = kfence_alloc(s, s->object_size, flags); > @@ -3942,7 +3943,7 @@ static inline int __kmem_cache_alloc_bul > */ > c->tid = next_tid(c->tid); > > - local_unlock_irq(&s->cpu_slab->lock); > + local_unlock_irqrestore(&s->cpu_slab->lock, irqflags); > > /* > * Invoking slow path likely have side-effect > @@ -3956,7 +3957,7 @@ static inline int __kmem_cache_alloc_bul > c = this_cpu_ptr(s->cpu_slab); > maybe_wipe_obj_freeptr(s, p[i]); > > - local_lock_irq(&s->cpu_slab->lock); > + local_lock_irqsave(&s->cpu_slab->lock, irqflags); > > continue; /* goto for-loop */ > } > @@ -3965,7 +3966,7 @@ static inline int __kmem_cache_alloc_bul > maybe_wipe_obj_freeptr(s, p[i]); > } > c->tid = next_tid(c->tid); > - local_unlock_irq(&s->cpu_slab->lock); > + local_unlock_irqrestore(&s->cpu_slab->lock, irqflags); > slub_put_cpu_ptr(s->cpu_slab); > > return i;
