linux-kernel - [RFC v2 17/34] mm, slub: check new pages with restored irqs

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Message-Id: <20210609113903.1421-18-vbabka@suse.cz>
Date:   Wed,  9 Jun 2021 13:38:46 +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 17/34] mm, slub: check new pages with restored irqs

Building on top of the previous patch, re-enable irqs before checking new
pages. alloc_debug_processing() is now called with enabled irqs so we need to
remove VM_BUG_ON(!irqs_disabled()); in check_slab() - there doesn't seem to be
a need for it anyway.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 mm/slub.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 378f1cb040b3..760080b58957 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -954,8 +954,6 @@ static int check_slab(struct kmem_cache *s, struct page *page)
 {
 	int maxobj;
 
-	VM_BUG_ON(!irqs_disabled());
-
 	if (!PageSlab(page)) {
 		slab_err(s, page, "Not a valid slab page");
 		return 0;
@@ -2729,10 +2727,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 	lockdep_assert_irqs_disabled();
 
 	freelist = get_partial(s, gfpflags, node, &page);
+	local_irq_restore(flags);
 	if (freelist)
 		goto check_new_page;
 
-	local_irq_restore(flags);
 	put_cpu_ptr(s->cpu_slab);
 	page = new_slab(s, gfpflags, node);
 	c = get_cpu_ptr(s->cpu_slab);
@@ -2742,7 +2740,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 		return NULL;
 	}
 
-	local_irq_save(flags);
 	/*
 	 * No other reference to the page yet so we can
 	 * muck around with it freely without cmpxchg
@@ -2757,7 +2754,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 	if (kmem_cache_debug(s)) {
 		if (!alloc_debug_processing(s, page, freelist, addr)) {
 			/* Slab failed checks. Next slab needed */
-			local_irq_restore(flags);
 			goto new_slab;
 		} else {
 			/*
@@ -2775,6 +2771,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 		 */
 		goto return_single;
 
+	local_irq_save(flags);
 	if (unlikely(c->page))
 		flush_slab(s, c);
 	c->page = page;
@@ -2783,6 +2780,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 
 return_single:
 
+	local_irq_save(flags);
 	if (unlikely(c->page))
 		flush_slab(s, c);
 	c->page = page;
-- 
2.31.1