[022/212] mm, slub: move disabling irqs closer to get_partial() in ___slab_alloc()

Commit Message

Andrew Morton Sept. 2, 2021, 9:51 p.m. UTC

From: Vlastimil Babka <[e-mail]>
Subject: mm, slub: move disabling irqs closer to get_partial() in ___slab_alloc()

Continue reducing the irq disabled scope.  Check for per-cpu partial slabs
with first with irqs enabled and then recheck with irqs disabled before
grabbing the slab page.  Mostly preparatory for the following patches.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Vlastimil Babka <[e-mail]>
Cc: Christoph Lameter <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: Jann Horn <[e-mail]>
Cc: Jesper Dangaard Brouer <[e-mail]>
Cc: Joonsoo Kim <[e-mail]>
Cc: Mel Gorman <[e-mail]>
Cc: Mike Galbraith <[e-mail]>
Cc: Pekka Enberg <[e-mail]>
Cc: Sebastian Andrzej Siewior <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/slub.c |   34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

Patch

--- a/mm/slub.c~mm-slub-move-disabling-irqs-closer-to-get_partial-in-___slab_alloc
+++ a/mm/slub.c
@@ -2692,11 +2692,6 @@  reread_page:
 		if (unlikely(node != NUMA_NO_NODE &&
 			     !node_isset(node, slab_nodes)))
 			node = NUMA_NO_NODE;
-		local_irq_save(flags);
-		if (unlikely(c->page)) {
-			local_irq_restore(flags);
-			goto reread_page;
-		}
 		goto new_slab;
 	}
 redo:
@@ -2737,6 +2732,7 @@  redo:
 
 	if (!freelist) {
 		c->page = NULL;
+		local_irq_restore(flags);
 		stat(s, DEACTIVATE_BYPASS);
 		goto new_slab;
 	}
@@ -2766,12 +2762,19 @@  deactivate_slab:
 		goto reread_page;
 	}
 	deactivate_slab(s, page, c->freelist, c);
+	local_irq_restore(flags);
 
 new_slab:
 
-	lockdep_assert_irqs_disabled();
-
 	if (slub_percpu_partial(c)) {
+		local_irq_save(flags);
+		if (unlikely(c->page)) {
+			local_irq_restore(flags);
+			goto reread_page;
+		}
+		if (unlikely(!slub_percpu_partial(c)))
+			goto new_objects; /* stolen by an IRQ handler */
+
 		page = c->page = slub_percpu_partial(c);
 		slub_set_percpu_partial(c, page);
 		local_irq_restore(flags);
@@ -2779,6 +2782,16 @@  new_slab:
 		goto redo;
 	}
 
+	local_irq_save(flags);
+	if (unlikely(c->page)) {
+		local_irq_restore(flags);
+		goto reread_page;
+	}
+
+new_objects:
+
+	lockdep_assert_irqs_disabled();
+
 	freelist = get_partial(s, gfpflags, node, &page);
 	if (freelist) {
 		c->page = page;
@@ -2811,15 +2824,18 @@  new_slab:
 check_new_page:
 
 	if (kmem_cache_debug(s)) {
-		if (!alloc_debug_processing(s, page, freelist, addr))
+		if (!alloc_debug_processing(s, page, freelist, addr)) {
 			/* Slab failed checks. Next slab needed */
+			c->page = NULL;
+			local_irq_restore(flags);
 			goto new_slab;
-		else
+		} else {
 			/*
 			 * For debug case, we don't load freelist so that all
 			 * allocations go through alloc_debug_processing()
 			 */
 			goto return_single;
+		}
 	}
 
 	if (unlikely(!pfmemalloc_match(page, gfpflags)))