+ mm-slub-move-irq-control-into-unfreeze_partials.patch added to -mm tree

+ mm-slub-move-irq-control-into-unfreeze_partials.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm, slub: move irq control into unfreeze_partials()
has been added to the -mm tree.  Its filename is
     mm-slub-move-irq-control-into-unfreeze_partials.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-move-irq-control-into-unfreeze_partials.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-move-irq-control-into-unfreeze_partials.patch

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------------------------------------------------------
From: Vlastimil Babka <vbabka@suse.cz>
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@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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;
_

Patches currently in -mm which might be from vbabka@suse.cz are

mm-slub-fix-slub_debug-disablement-for-list-of-slabs.patch
mm-slub-dont-call-flush_all-from-slab_debug_trace_open.patch
mm-slub-allocate-private-object-map-for-debugfs-listings.patch
mm-slub-allocate-private-object-map-for-validate_slab_cache.patch
mm-slub-dont-disable-irq-for-debug_check_no_locks_freed.patch
mm-slub-remove-redundant-unfreeze_partials-from-put_cpu_partial.patch
mm-slub-unify-cmpxchg_double_slab-and-__cmpxchg_double_slab.patch
mm-slub-extract-get_partial-from-new_slab_objects.patch
mm-slub-dissolve-new_slab_objects-into-___slab_alloc.patch
mm-slub-return-slab-page-from-get_partial-and-set-c-page-afterwards.patch
mm-slub-restructure-new-page-checks-in-___slab_alloc.patch
mm-slub-simplify-kmem_cache_cpu-and-tid-setup.patch
mm-slub-move-disabling-enabling-irqs-to-___slab_alloc.patch
mm-slub-do-initial-checks-in-___slab_alloc-with-irqs-enabled.patch
mm-slub-move-disabling-irqs-closer-to-get_partial-in-___slab_alloc.patch
mm-slub-restore-irqs-around-calling-new_slab.patch
mm-slub-validate-slab-from-partial-list-or-page-allocator-before-making-it-cpu-slab.patch
mm-slub-check-new-pages-with-restored-irqs.patch
mm-slub-stop-disabling-irqs-around-get_partial.patch
mm-slub-move-reset-of-c-page-and-freelist-out-of-deactivate_slab.patch
mm-slub-make-locking-in-deactivate_slab-irq-safe.patch
mm-slub-call-deactivate_slab-without-disabling-irqs.patch
mm-slub-move-irq-control-into-unfreeze_partials.patch
mm-slub-discard-slabs-in-unfreeze_partials-without-irqs-disabled.patch
mm-slub-detach-whole-partial-list-at-once-in-unfreeze_partials.patch
mm-slub-separate-detaching-of-partial-list-in-unfreeze_partials-from-unfreezing.patch
mm-slub-only-disable-irq-with-spin_lock-in-__unfreeze_partials.patch
mm-slub-dont-disable-irqs-in-slub_cpu_dead.patch
mm-slab-make-flush_slab-possible-to-call-with-irqs-enabled.patch
mm-slub-optionally-save-restore-irqs-in-slab_lock.patch
mm-slub-make-slab_lock-disable-irqs-with-preempt_rt.patch
mm-slub-protect-put_cpu_partial-with-disabled-irqs-instead-of-cmpxchg.patch
mm-slub-use-migrate_disable-on-preempt_rt.patch
mm-slub-convert-kmem_cpu_slab-protection-to-local_lock.patch