From: Vlastimil Babka <vbabka@suse.cz>
Date: Mon, 23 Aug 2021 23:58:57 +0000 (+1000)
Subject: mm, slub: move disabling irqs closer to get_partial() in ___slab_alloc()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d1e19a041272049a7668567ad955ddc12982282b;p=users%2Fjedix%2Flinux-maple.git

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/20210805152000.12817-15-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>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---

diff --git a/mm/slub.c b/mm/slub.c
index fcc38638c645..a437730d7ae2 100644
--- a/mm/slub.c
+++ b/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)))