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From:   Vlastimil Babka <vbabka@suse.cz>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@kernel.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Mike Galbraith <efault@gmx.de>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Mel Gorman <mgorman@techsingularity.net>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        Jann Horn <jannh@google.com>, Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH v4 17/35] mm, slub: check new pages with restored irqs
Date:   Thu,  5 Aug 2021 17:19:42 +0200
Message-Id: <20210805152000.12817-18-vbabka@suse.cz>
In-Reply-To: <20210805152000.12817-1-vbabka@suse.cz>
References: <20210805152000.12817-1-vbabka@suse.cz>
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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@suse.cz>
---
 mm/slub.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 5d58fde2bd70..f7c6cebb524d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -995,8 +995,6 @@ 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;
@@ -2772,10 +2770,10 @@ 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);
@@ -2785,7 +2783,6 @@ 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
@@ -2800,7 +2797,6 @@ 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 {
 			/*
@@ -2818,6 +2814,7 @@ 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;
@@ -2826,6 +2823,7 @@ 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;
-- 
2.32.0