linux-kernel - [RFC v2 04/34] mm, slub: don't disable irq for debug_check_no_locks

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Message-Id: <20210609113903.1421-5-vbabka@suse.cz>
Date:   Wed,  9 Jun 2021 13:38:33 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Pekka Enberg <penberg@...nel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jann Horn <jannh@...gle.com>, Vlastimil Babka <vbabka@...e.cz>
Subject: [RFC v2 04/34] mm, slub: don't disable irq for debug_check_no_locks_freed()

In slab_free_hook() we disable irqs around the debug_check_no_locks_freed()
call, which is unnecessary, as irqs are already being disabled inside the call.
This seems to be leftover from the past where there were more calls inside the
irq disabled sections. Remove the irq disable/enable operations.

Mel noted:
> Looks like it was needed for kmemcheck which went away back in 4.15

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
Acked-by: Mel Gorman <mgorman@...hsingularity.net>
---
 mm/slub.c | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 5a940bd3cebb..2953f6e43cae 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1545,20 +1545,8 @@ static __always_inline bool slab_free_hook(struct kmem_cache *s,
 {
 	kmemleak_free_recursive(x, s->flags);
 
-	/*
-	 * Trouble is that we may no longer disable interrupts in the fast path
-	 * So in order to make the debug calls that expect irqs to be
-	 * disabled we need to disable interrupts temporarily.
-	 */
-#ifdef CONFIG_LOCKDEP
-	{
-		unsigned long flags;
+	debug_check_no_locks_freed(x, s->object_size);
 
-		local_irq_save(flags);
-		debug_check_no_locks_freed(x, s->object_size);
-		local_irq_restore(flags);
-	}
-#endif
 	if (!(s->flags & SLAB_DEBUG_OBJECTS))
 		debug_check_no_obj_freed(x, s->object_size);
 
-- 
2.31.1