From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm, slub: move irq control into unfreeze_partials() unfreeze_partials() can be optimized so that it doesn't need irqs disabled for the whole time. As the first step, move irq control into the function and remove it from the put_cpu_partial() caller. Link: https://lkml.kernel.org/r/20210805152000.12817-23-vbabka@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: 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 | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/mm/slub.c~mm-slub-move-irq-control-into-unfreeze_partials +++ a/mm/slub.c @@ -2336,9 +2336,8 @@ redo: /* * Unfreeze all the cpu partial slabs. * - * This function must be called with interrupts disabled - * for the cpu using c (or some other guarantee must be there - * to guarantee no concurrent accesses). + * This function must be called with preemption or migration + * disabled with c local to the cpu. */ static void unfreeze_partials(struct kmem_cache *s, struct kmem_cache_cpu *c) @@ -2346,6 +2345,9 @@ static void unfreeze_partials(struct kme #ifdef CONFIG_SLUB_CPU_PARTIAL struct kmem_cache_node *n = NULL, *n2 = NULL; struct page *page, *discard_page = NULL; + unsigned long flags; + + local_irq_save(flags); while ((page = slub_percpu_partial(c))) { struct page new; @@ -2398,6 +2400,8 @@ static void unfreeze_partials(struct kme discard_slab(s, page); stat(s, FREE_SLAB); } + + local_irq_restore(flags); #endif /* CONFIG_SLUB_CPU_PARTIAL */ } @@ -2425,14 +2429,11 @@ static void put_cpu_partial(struct kmem_ pobjects = oldpage->pobjects; pages = oldpage->pages; if (drain && pobjects > slub_cpu_partial(s)) { - unsigned long flags; /* * partial array is full. Move the existing * set to the per node partial list. */ - local_irq_save(flags); unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); - local_irq_restore(flags); oldpage = NULL; pobjects = 0; pages = 0; _
