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From: Jens Axboe <axboe@kernel.dk>
To: LKML <linux-kernel@vger.kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH] mm: don't call should_failslab() for !CONFIG_FAILSLAB
Date: Tue, 5 Oct 2021 09:31:43 -0600	[thread overview]
Message-ID: <e01e5e40-692a-519c-4cba-e3331f173c82@kernel.dk> (raw)

Allocations can be a very hot path, and this out-of-line function
call is noticeable.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h
index e525f6957c49..3128d2c8b3b4 100644
--- a/include/linux/fault-inject.h
+++ b/include/linux/fault-inject.h
@@ -64,8 +64,8 @@ static inline struct dentry *fault_create_debugfs_attr(const char *name,
 
 struct kmem_cache;
 
-int should_failslab(struct kmem_cache *s, gfp_t gfpflags);
 #ifdef CONFIG_FAILSLAB
+int should_failslab(struct kmem_cache *s, gfp_t gfpflags);
 extern bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags);
 #else
 static inline bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags)
diff --git a/mm/slab.h b/mm/slab.h
index 58c01a34e5b8..92fd6fe01877 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -491,8 +491,10 @@ static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
 
 	might_alloc(flags);
 
+#ifdef CONFIG_FAILSLAB
 	if (should_failslab(s, flags))
 		return NULL;
+#endif
 
 	if (!memcg_slab_pre_alloc_hook(s, objcgp, size, flags))
 		return NULL;
diff --git a/mm/slab_common.c b/mm/slab_common.c
index ec2bb0beed75..c21bd447f237 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1323,6 +1323,7 @@ EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
 EXPORT_TRACEPOINT_SYMBOL(kfree);
 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
 
+#ifdef CONFIG_FAILSLAB
 int should_failslab(struct kmem_cache *s, gfp_t gfpflags)
 {
 	if (__should_failslab(s, gfpflags))
@@ -1330,3 +1331,4 @@ int should_failslab(struct kmem_cache *s, gfp_t gfpflags)
 	return 0;
 }
 ALLOW_ERROR_INJECTION(should_failslab, ERRNO);
+#endif

-- 
Jens Axboe



             reply	other threads:[~2021-10-05 15:31 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-05 15:31 Jens Axboe [this message]
2021-10-05 21:18 ` [PATCH] mm: don't call should_failslab() for !CONFIG_FAILSLAB Andrew Morton
2021-10-05 21:20   ` Jens Axboe
2021-10-07 15:32 ` Vlastimil Babka
2021-10-07 15:50   ` Jens Axboe
2021-10-07 16:36   ` Konstantin Ryabitsev

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