| Message ID | 20241112-slub-percpu-caches-v1-2-ddc0bdc27e05@suse.cz (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | SLUB percpu sheaves | expand |
On Tue, Nov 12, 2024 at 05:38:46PM +0100, Vlastimil Babka wrote: > Extend the sheaf infrastructure for more efficient kfree_rcu() handling. > For caches where sheafs are initialized, on each cpu maintain a rcu_free > sheaf in addition to main and spare sheaves. > > kfree_rcu() operations will try to put objects on this sheaf. Once full, > the sheaf is detached and submitted to call_rcu() with a handler that > will try to put in on the barn, or flush to slab pages using bulk free, > when the barn is full. Then a new empty sheaf must be obtained to put > more objects there. > > It's possible that no free sheafs are available to use for a new > rcu_free sheaf, and the allocation in kfree_rcu() context can only use > GFP_NOWAIT and thus may fail. In that case, fall back to the existing > kfree_rcu() machinery. > > Because some intended users will need to perform additonal cleanups > after the grace period and thus have custom rcu_call() callbacks today, > add the possibility to specify a kfree_rcu() specific destructor. > Because of the fall back possibility, the destructor now needs be > invoked also from within RCU, so add __kvfree_rcu() that RCU can use > instead of kvfree(). > > Expected advantages: > - batching the kfree_rcu() operations, that could eventually replace the > batching done in RCU itself > - sheafs can be reused via barn instead of being flushed to slabs, which > is more effective > - this includes cases where only some cpus are allowed to process rcu > callbacks (Android) > > Possible disadvantage: > - objects might be waiting for more than their grace period (it is > determined by the last object freed into the sheaf), increasing memory > usage - but that might be true for the batching done by RCU as well? > > RFC LIMITATIONS: - only tree rcu is converted, not tiny > - the rcu fallback might resort to kfree_bulk(), not kvfree(). Instead > of adding a variant of kfree_bulk() with destructors, is there an easy > way to disable the kfree_bulk() path in the fallback case? > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > --- > include/linux/slab.h | 15 +++++ > kernel/rcu/tree.c | 8 ++- > mm/slab.h | 25 +++++++ > mm/slab_common.c | 3 + > mm/slub.c | 182 +++++++++++++++++++++++++++++++++++++++++++++++++-- > 5 files changed, 227 insertions(+), 6 deletions(-) > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index b13fb1c1f03c14a5b45bc6a64a2096883aef9f83..23904321992ad2eeb9389d0883cf4d5d5d71d896 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -343,6 +343,21 @@ struct kmem_cache_args { > * %0 means no sheaves will be created > */ > unsigned int sheaf_capacity; > + /** > + * @sheaf_rcu_dtor: A destructor for objects freed by kfree_rcu() > + * > + * Only valid when non-zero @sheaf_capacity is specified. When freeing > + * objects by kfree_rcu() in a cache with sheaves, the objects are put > + * to a special percpu sheaf. When that sheaf is full, it's passed to > + * call_rcu() and after a grace period the sheaf can be reused for new > + * allocations. In case a cleanup is necessary after the grace period > + * and before reusal, a pointer to such function can be given as > + * @sheaf_rcu_dtor and will be called on each object in the rcu sheaf > + * after the grace period passes and before the sheaf's reuse. > + * > + * %NULL means no destructor is called. > + */ > + void (*sheaf_rcu_dtor)(void *obj); > }; > > struct kmem_cache *__kmem_cache_create_args(const char *name, > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index b1f883fcd9185a5e22c10102d1024c40688f57fb..42c994fdf9960bfed8d8bd697de90af72c1f4f58 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -65,6 +65,7 @@ > #include <linux/kasan.h> > #include <linux/context_tracking.h> > #include "../time/tick-internal.h" > +#include "../../mm/slab.h" > > #include "tree.h" > #include "rcu.h" > @@ -3420,7 +3421,7 @@ kvfree_rcu_list(struct rcu_head *head) > trace_rcu_invoke_kvfree_callback(rcu_state.name, head, offset); > > if (!WARN_ON_ONCE(!__is_kvfree_rcu_offset(offset))) > - kvfree(ptr); > + __kvfree_rcu(ptr); > > rcu_lock_release(&rcu_callback_map); > cond_resched_tasks_rcu_qs(); > @@ -3797,6 +3798,9 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr) > if (!head) > might_sleep(); > > + if (kfree_rcu_sheaf(ptr)) > + return; > + > This change crosses all effort which has been done in order to improve kvfree_rcu :) For example: performance, app launch improvements for Android devices; memory consumption optimizations to minimize LMK triggering; batching to speed-up offloading; etc. So we have done a lot of work there. We were thinking about moving all functionality from "kernel/rcu" to "mm/". As a first step i can do that, i.e. move kvfree_rcu() as is. After that we can switch to second step. Sounds good for you or not? -- Uladzislau Rezki
On 11/14/24 17:57, Uladzislau Rezki wrote: > On Tue, Nov 12, 2024 at 05:38:46PM +0100, Vlastimil Babka wrote: >> --- a/kernel/rcu/tree.c >> +++ b/kernel/rcu/tree.c >> @@ -65,6 +65,7 @@ >> #include <linux/kasan.h> >> #include <linux/context_tracking.h> >> #include "../time/tick-internal.h" >> +#include "../../mm/slab.h" >> >> #include "tree.h" >> #include "rcu.h" >> @@ -3420,7 +3421,7 @@ kvfree_rcu_list(struct rcu_head *head) >> trace_rcu_invoke_kvfree_callback(rcu_state.name, head, offset); >> >> if (!WARN_ON_ONCE(!__is_kvfree_rcu_offset(offset))) >> - kvfree(ptr); >> + __kvfree_rcu(ptr); >> >> rcu_lock_release(&rcu_callback_map); >> cond_resched_tasks_rcu_qs(); >> @@ -3797,6 +3798,9 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr) >> if (!head) >> might_sleep(); >> >> + if (kfree_rcu_sheaf(ptr)) >> + return; >> + >> > This change crosses all effort which has been done in order to improve kvfree_rcu :) Yeah I know, but it wasn't intended to make it all obsolete as I don't think every kfree_rcu() user would have a sheaf-enabled cache. > For example: > performance, app launch improvements for Android devices; > memory consumption optimizations to minimize LMK triggering; > batching to speed-up offloading; > etc. Yes it's a great effort that I appreciate and you did probably all that was possible to do without changing the slab allocator itself. > So we have done a lot of work there. We were thinking about moving all > functionality from "kernel/rcu" to "mm/". As a first step i can do that, > i.e. move kvfree_rcu() as is. After that we can switch to second step. Yeah we have discussed that with Paul at LSF/MM as well and I agreed it makes sense, but didn't get to it yet. > Sounds good for you or not? Sounds good, thanks! > -- > Uladzislau Rezki
On Sun, Nov 17, 2024 at 12:01:01PM +0100, Vlastimil Babka wrote: > On 11/14/24 17:57, Uladzislau Rezki wrote: > > On Tue, Nov 12, 2024 at 05:38:46PM +0100, Vlastimil Babka wrote: > >> --- a/kernel/rcu/tree.c > >> +++ b/kernel/rcu/tree.c > >> @@ -65,6 +65,7 @@ > >> #include <linux/kasan.h> > >> #include <linux/context_tracking.h> > >> #include "../time/tick-internal.h" > >> +#include "../../mm/slab.h" > >> > >> #include "tree.h" > >> #include "rcu.h" > >> @@ -3420,7 +3421,7 @@ kvfree_rcu_list(struct rcu_head *head) > >> trace_rcu_invoke_kvfree_callback(rcu_state.name, head, offset); > >> > >> if (!WARN_ON_ONCE(!__is_kvfree_rcu_offset(offset))) > >> - kvfree(ptr); > >> + __kvfree_rcu(ptr); > >> > >> rcu_lock_release(&rcu_callback_map); > >> cond_resched_tasks_rcu_qs(); > >> @@ -3797,6 +3798,9 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr) > >> if (!head) > >> might_sleep(); > >> > >> + if (kfree_rcu_sheaf(ptr)) > >> + return; > >> + > >> > > This change crosses all effort which has been done in order to improve kvfree_rcu :) > > Yeah I know, but it wasn't intended to make it all obsolete as I don't think > every kfree_rcu() user would have a sheaf-enabled cache. > > > For example: > > performance, app launch improvements for Android devices; > > memory consumption optimizations to minimize LMK triggering; > > batching to speed-up offloading; > > etc. > > Yes it's a great effort that I appreciate and you did probably all that was > possible to do without changing the slab allocator itself. > > > So we have done a lot of work there. We were thinking about moving all > > functionality from "kernel/rcu" to "mm/". As a first step i can do that, > > i.e. move kvfree_rcu() as is. After that we can switch to second step. > > Yeah we have discussed that with Paul at LSF/MM as well and I agreed it > makes sense, but didn't get to it yet. > > > Sounds good for you or not? > > Sounds good, thanks! > Thank you. Let me try to start moving it into mm/. I am thinking to place it to the slab_common.c file. I am not sure if it makes sense to have a dedicated file name for this purpose. Anyway, share your view if you want to add something. Otherwise i can proceed with that process. -- Uladzislau Rezki
diff --git a/include/linux/slab.h b/include/linux/slab.h index b13fb1c1f03c14a5b45bc6a64a2096883aef9f83..23904321992ad2eeb9389d0883cf4d5d5d71d896 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -343,6 +343,21 @@ struct kmem_cache_args { * %0 means no sheaves will be created */ unsigned int sheaf_capacity; + /** + * @sheaf_rcu_dtor: A destructor for objects freed by kfree_rcu() + * + * Only valid when non-zero @sheaf_capacity is specified. When freeing + * objects by kfree_rcu() in a cache with sheaves, the objects are put + * to a special percpu sheaf. When that sheaf is full, it's passed to + * call_rcu() and after a grace period the sheaf can be reused for new + * allocations. In case a cleanup is necessary after the grace period + * and before reusal, a pointer to such function can be given as + * @sheaf_rcu_dtor and will be called on each object in the rcu sheaf + * after the grace period passes and before the sheaf's reuse. + * + * %NULL means no destructor is called. + */ + void (*sheaf_rcu_dtor)(void *obj); }; struct kmem_cache *__kmem_cache_create_args(const char *name, diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index b1f883fcd9185a5e22c10102d1024c40688f57fb..42c994fdf9960bfed8d8bd697de90af72c1f4f58 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -65,6 +65,7 @@ #include <linux/kasan.h> #include <linux/context_tracking.h> #include "../time/tick-internal.h" +#include "../../mm/slab.h" #include "tree.h" #include "rcu.h" @@ -3420,7 +3421,7 @@ kvfree_rcu_list(struct rcu_head *head) trace_rcu_invoke_kvfree_callback(rcu_state.name, head, offset); if (!WARN_ON_ONCE(!__is_kvfree_rcu_offset(offset))) - kvfree(ptr); + __kvfree_rcu(ptr); rcu_lock_release(&rcu_callback_map); cond_resched_tasks_rcu_qs(); @@ -3797,6 +3798,9 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr) if (!head) might_sleep(); + if (kfree_rcu_sheaf(ptr)) + return; + // Queue the object but don't yet schedule the batch. if (debug_rcu_head_queue(ptr)) { // Probable double kfree_rcu(), just leak. @@ -3849,7 +3853,7 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr) if (!success) { debug_rcu_head_unqueue((struct rcu_head *) ptr); synchronize_rcu(); - kvfree(ptr); + __kvfree_rcu(ptr); } } EXPORT_SYMBOL_GPL(kvfree_call_rcu); diff --git a/mm/slab.h b/mm/slab.h index 001e0d55467bb4803b5dff718ba8e0c775f42b3f..4dc145c14dfd97677c74a767c22f5dd22f5d6451 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -276,6 +276,9 @@ struct kmem_cache { gfp_t allocflags; /* gfp flags to use on each alloc */ int refcount; /* Refcount for slab cache destroy */ void (*ctor)(void *object); /* Object constructor */ + void (*rcu_dtor)(void *object); /* Object destructor to execute after + * kfree_rcu grace period + */ unsigned int inuse; /* Offset to metadata */ unsigned int align; /* Alignment */ unsigned int red_left_pad; /* Left redzone padding size */ @@ -454,6 +457,28 @@ static inline bool is_kmalloc_normal(struct kmem_cache *s) return !(s->flags & (SLAB_CACHE_DMA|SLAB_ACCOUNT|SLAB_RECLAIM_ACCOUNT)); } +void __kvfree_rcu(void *obj); + +bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj); + +static inline bool kfree_rcu_sheaf(void *obj) +{ + struct kmem_cache *s; + struct folio *folio; + struct slab *slab; + + folio = virt_to_folio(obj); + if (unlikely(!folio_test_slab(folio))) + return false; + + slab = folio_slab(folio); + s = slab->slab_cache; + if (s->cpu_sheaves) + return __kfree_rcu_sheaf(s, obj); + + return false; +} + /* Legal flag mask for kmem_cache_create(), for various configurations */ #define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | \ SLAB_CACHE_DMA32 | SLAB_PANIC | \ diff --git a/mm/slab_common.c b/mm/slab_common.c index 7939f3f017740e0ac49ffa971c45409d0fbe2f23..d69ed1e7ea34f9657cb9514fb98a48647f01381b 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -236,6 +236,9 @@ static struct kmem_cache *create_cache(const char *name, !IS_ALIGNED(args->freeptr_offset, sizeof(freeptr_t)))) goto out; + if (args->sheaf_rcu_dtor && !args->sheaf_capacity) + goto out; + err = -ENOMEM; s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); if (!s) diff --git a/mm/slub.c b/mm/slub.c index 7da08112213b203993b5159eb35a1ea640d706fe..6811d766c0470cd7066c2574ad86e00405c916bb 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -351,6 +351,8 @@ enum stat_item { ALLOC_FASTPATH, /* Allocation from cpu slab */ ALLOC_SLOWPATH, /* Allocation by getting a new cpu slab */ FREE_PCS, /* Free to percpu sheaf */ + FREE_RCU_SHEAF, /* Free to rcu_free sheaf */ + FREE_RCU_SHEAF_FAIL, /* Failed to free to a rcu_free sheaf */ FREE_FASTPATH, /* Free to cpu slab */ FREE_SLOWPATH, /* Freeing not to cpu slab */ FREE_FROZEN, /* Freeing to frozen slab */ @@ -2557,6 +2559,24 @@ static void sheaf_flush(struct kmem_cache *s, struct slab_sheaf *sheaf) sheaf->size = 0; } +static void __rcu_free_sheaf_prepare(struct kmem_cache *s, + struct slab_sheaf *sheaf); + +static void rcu_free_sheaf_nobarn(struct rcu_head *head) +{ + struct slab_sheaf *sheaf; + struct kmem_cache *s; + + sheaf = container_of(head, struct slab_sheaf, rcu_head); + s = sheaf->cache; + + __rcu_free_sheaf_prepare(s, sheaf); + + sheaf_flush(s, sheaf); + + free_empty_sheaf(s, sheaf); +} + /* * Caller needs to make sure migration is disabled in order to fully flush * single cpu's sheaves @@ -2586,8 +2606,8 @@ static void pcs_flush_all(struct kmem_cache *s) free_empty_sheaf(s, spare); } - // TODO: handle rcu_free - BUG_ON(rcu_free); + if (rcu_free) + call_rcu(&rcu_free->rcu_head, rcu_free_sheaf_nobarn); sheaf_flush_main(s); } @@ -2604,8 +2624,10 @@ static void __pcs_flush_all_cpu(struct kmem_cache *s, unsigned int cpu) pcs->spare = NULL; } - // TODO: handle rcu_free - BUG_ON(pcs->rcu_free); + if (pcs->rcu_free) { + call_rcu(&pcs->rcu_free->rcu_head, rcu_free_sheaf_nobarn); + pcs->rcu_free = NULL; + } sheaf_flush_main(s); } @@ -5161,6 +5183,121 @@ void free_to_pcs(struct kmem_cache *s, void *object) stat(s, FREE_PCS); } +static void __rcu_free_sheaf_prepare(struct kmem_cache *s, + struct slab_sheaf *sheaf) +{ + bool init = slab_want_init_on_free(s); + void **p = &sheaf->objects[0]; + unsigned int i = 0; + + while (i < sheaf->size) { + struct slab *slab = virt_to_slab(p[i]); + + if (s->rcu_dtor) + s->rcu_dtor(p[i]); + + memcg_slab_free_hook(s, slab, p + i, 1); + alloc_tagging_slab_free_hook(s, slab, p + i, 1); + + if (unlikely(!slab_free_hook(s, p[i], init, false))) { + p[i] = p[--sheaf->size]; + continue; + } + + i++; + } +} + +static void rcu_free_sheaf(struct rcu_head *head) +{ + struct slab_sheaf *sheaf; + struct node_barn *barn; + struct kmem_cache *s; + + sheaf = container_of(head, struct slab_sheaf, rcu_head); + + s = sheaf->cache; + + __rcu_free_sheaf_prepare(s, sheaf); + + barn = get_node(s, numa_mem_id())->barn; + + /* due to slab_free_hook() */ + if (unlikely(sheaf->size == 0)) + goto empty; + + if (!barn_put_full_sheaf(barn, sheaf, false)) + return; + + sheaf_flush(s, sheaf); + +empty: + if (!barn_put_empty_sheaf(barn, sheaf, false)) + return; + + free_empty_sheaf(s, sheaf); +} + +bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj) +{ + struct slub_percpu_sheaves *pcs; + struct slab_sheaf *rcu_sheaf; + unsigned long flags; + + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (unlikely(!pcs->rcu_free)) { + + struct slab_sheaf *empty; + + empty = barn_get_empty_sheaf(pcs->barn); + + if (empty) { + pcs->rcu_free = empty; + goto do_free; + } + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + empty = alloc_empty_sheaf(s, GFP_NOWAIT); + + if (!empty) { + stat(s, FREE_RCU_SHEAF_FAIL); + return false; + } + + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (unlikely(pcs->rcu_free)) + barn_put_empty_sheaf(pcs->barn, empty, true); + else + pcs->rcu_free = empty; + } + +do_free: + + rcu_sheaf = pcs->rcu_free; + + rcu_sheaf->objects[rcu_sheaf->size++] = obj; + + if (likely(rcu_sheaf->size < s->sheaf_capacity)) { + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + stat(s, FREE_RCU_SHEAF); + return true; + } + + pcs->rcu_free = NULL; + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + call_rcu(&rcu_sheaf->rcu_head, rcu_free_sheaf); + + stat(s, FREE_RCU_SHEAF); + + return true; +} + /* * Bulk free objects to the percpu sheaves. * Unlike free_to_pcs() this includes the calls to all necessary hooks @@ -5466,6 +5603,32 @@ static void free_large_kmalloc(struct folio *folio, void *object) folio_put(folio); } +void __kvfree_rcu(void *obj) +{ + struct folio *folio; + struct slab *slab; + struct kmem_cache *s; + + if (is_vmalloc_addr(obj)) { + vfree(obj); + return; + } + + folio = virt_to_folio(obj); + if (unlikely(!folio_test_slab(folio))) { + free_large_kmalloc(folio, obj); + return; + } + + slab = folio_slab(folio); + s = slab->slab_cache; + + if (s->rcu_dtor) + s->rcu_dtor(obj); + + slab_free(s, slab, obj, _RET_IP_); +} + /** * kfree - free previously allocated memory * @object: pointer returned by kmalloc() or kmem_cache_alloc() @@ -6326,6 +6489,11 @@ int __kmem_cache_shutdown(struct kmem_cache *s) struct kmem_cache_node *n; flush_all_cpus_locked(s); + + /* we might have rcu sheaves in flight */ + if (s->cpu_sheaves) + rcu_barrier(); + /* Attempt to free all objects */ for_each_kmem_cache_node(s, node, n) { if (n->barn) @@ -6887,6 +7055,8 @@ int do_kmem_cache_create(struct kmem_cache *s, const char *name, } // TODO: increase capacity to grow slab_sheaf up to next kmalloc size? s->sheaf_capacity = args->sheaf_capacity; + + s->rcu_dtor = args->sheaf_rcu_dtor; } #ifdef CONFIG_NUMA @@ -7710,6 +7880,8 @@ STAT_ATTR(ALLOC_PCS, alloc_cpu_sheaf); STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath); STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath); STAT_ATTR(FREE_PCS, free_cpu_sheaf); +STAT_ATTR(FREE_RCU_SHEAF, free_rcu_sheaf); +STAT_ATTR(FREE_RCU_SHEAF_FAIL, free_rcu_sheaf_fail); STAT_ATTR(FREE_FASTPATH, free_fastpath); STAT_ATTR(FREE_SLOWPATH, free_slowpath); STAT_ATTR(FREE_FROZEN, free_frozen); @@ -7805,6 +7977,8 @@ static struct attribute *slab_attrs[] = { &alloc_fastpath_attr.attr, &alloc_slowpath_attr.attr, &free_cpu_sheaf_attr.attr, + &free_rcu_sheaf_attr.attr, + &free_rcu_sheaf_fail_attr.attr, &free_fastpath_attr.attr, &free_slowpath_attr.attr, &free_frozen_attr.attr,
Extend the sheaf infrastructure for more efficient kfree_rcu() handling. For caches where sheafs are initialized, on each cpu maintain a rcu_free sheaf in addition to main and spare sheaves. kfree_rcu() operations will try to put objects on this sheaf. Once full, the sheaf is detached and submitted to call_rcu() with a handler that will try to put in on the barn, or flush to slab pages using bulk free, when the barn is full. Then a new empty sheaf must be obtained to put more objects there. It's possible that no free sheafs are available to use for a new rcu_free sheaf, and the allocation in kfree_rcu() context can only use GFP_NOWAIT and thus may fail. In that case, fall back to the existing kfree_rcu() machinery. Because some intended users will need to perform additonal cleanups after the grace period and thus have custom rcu_call() callbacks today, add the possibility to specify a kfree_rcu() specific destructor. Because of the fall back possibility, the destructor now needs be invoked also from within RCU, so add __kvfree_rcu() that RCU can use instead of kvfree(). Expected advantages: - batching the kfree_rcu() operations, that could eventually replace the batching done in RCU itself - sheafs can be reused via barn instead of being flushed to slabs, which is more effective - this includes cases where only some cpus are allowed to process rcu callbacks (Android) Possible disadvantage: - objects might be waiting for more than their grace period (it is determined by the last object freed into the sheaf), increasing memory usage - but that might be true for the batching done by RCU as well? RFC LIMITATIONS: - only tree rcu is converted, not tiny - the rcu fallback might resort to kfree_bulk(), not kvfree(). Instead of adding a variant of kfree_bulk() with destructors, is there an easy way to disable the kfree_bulk() path in the fallback case? Signed-off-by: Vlastimil Babka <vbabka@suse.cz> --- include/linux/slab.h | 15 +++++ kernel/rcu/tree.c | 8 ++- mm/slab.h | 25 +++++++ mm/slab_common.c | 3 + mm/slub.c | 182 +++++++++++++++++++++++++++++++++++++++++++++++++-- 5 files changed, 227 insertions(+), 6 deletions(-)