From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm, slub: unify cmpxchg_double_slab() and __cmpxchg_double_slab() These functions differ only in irq disabling in the slow path. We can create a common function with an extra bool parameter to control the irq disabling. As the functions are inline and the parameter compile-time constant, there will be no runtime overhead due to this change. Also change the DEBUG_VM based irqs disable assert to the more standard lockdep_assert based one. Link: https://lkml.kernel.org/r/20210805152000.12817-7-vbabka@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Christoph Lameter <cl@xxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 62 ++++++++++++++++++++-------------------------------- 1 file changed, 24 insertions(+), 38 deletions(-) --- a/mm/slub.c~mm-slub-unify-cmpxchg_double_slab-and-__cmpxchg_double_slab +++ a/mm/slub.c @@ -371,13 +371,13 @@ static __always_inline void slab_unlock( __bit_spin_unlock(PG_locked, &page->flags); } -/* Interrupts must be disabled (for the fallback code to work right) */ -static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page, +static inline bool ___cmpxchg_double_slab(struct kmem_cache *s, struct page *page, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, - const char *n) + const char *n, bool disable_irqs) { - VM_BUG_ON(!irqs_disabled()); + if (!disable_irqs) + lockdep_assert_irqs_disabled(); #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) if (s->flags & __CMPXCHG_DOUBLE) { @@ -388,15 +388,23 @@ static inline bool __cmpxchg_double_slab } else #endif { + unsigned long flags; + + if (disable_irqs) + local_irq_save(flags); slab_lock(page); if (page->freelist == freelist_old && page->counters == counters_old) { page->freelist = freelist_new; page->counters = counters_new; slab_unlock(page); + if (disable_irqs) + local_irq_restore(flags); return true; } slab_unlock(page); + if (disable_irqs) + local_irq_restore(flags); } cpu_relax(); @@ -409,45 +417,23 @@ static inline bool __cmpxchg_double_slab return false; } -static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, +/* Interrupts must be disabled (for the fallback code to work right) */ +static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, const char *n) { -#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ - defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) - if (s->flags & __CMPXCHG_DOUBLE) { - if (cmpxchg_double(&page->freelist, &page->counters, - freelist_old, counters_old, - freelist_new, counters_new)) - return true; - } else -#endif - { - unsigned long flags; - - local_irq_save(flags); - slab_lock(page); - if (page->freelist == freelist_old && - page->counters == counters_old) { - page->freelist = freelist_new; - page->counters = counters_new; - slab_unlock(page); - local_irq_restore(flags); - return true; - } - slab_unlock(page); - local_irq_restore(flags); - } - - cpu_relax(); - stat(s, CMPXCHG_DOUBLE_FAIL); - -#ifdef SLUB_DEBUG_CMPXCHG - pr_info("%s %s: cmpxchg double redo ", n, s->name); -#endif + return ___cmpxchg_double_slab(s, page, freelist_old, counters_old, + freelist_new, counters_new, n, false); +} - return false; +static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, + void *freelist_old, unsigned long counters_old, + void *freelist_new, unsigned long counters_new, + const char *n) +{ + return ___cmpxchg_double_slab(s, page, freelist_old, counters_old, + freelist_new, counters_new, n, true); } #ifdef CONFIG_SLUB_DEBUG _
