linux-kernel - [PATCH v1 1/5] mm/vmalloc.c: Introduce vfree

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Date:   Wed, 28 Apr 2021 15:44:18 +0200
From:   "Uladzislau Rezki (Sony)" <urezki@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
        "Paul E . McKenney" <paulmck@...nel.org>
Cc:     Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Daniel Axtens <dja@...ens.net>,
        Frederic Weisbecker <frederic@...nel.org>,
        Neeraj Upadhyay <neeraju@...eaurora.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Theodore Y . Ts'o" <tytso@....edu>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Uladzislau Rezki <urezki@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
        Matthew Wilcox <willy@...radead.org>
Subject: [PATCH v1 1/5] mm/vmalloc.c: Introduce vfree_bulk() interface

Provide vfree_bulk() function and make it public. Some users
need to vfree vmalloc ptrs. as one set of batch. For example
there is a kvfree_rcu() API that keeps pointers in array.

As of now start with a simple implementation of vmalloc-bulk
interface that can be improved step by step in the future.

To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Matthew Wilcox (Oracle) <willy@...radead.org>
Suggested-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 include/linux/vmalloc.h |  1 +
 mm/vmalloc.c            | 31 +++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 3de7be6dd17c..bef1588c165b 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -112,6 +112,7 @@ void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
 
 extern void vfree(const void *addr);
 extern void vfree_atomic(const void *addr);
+extern void vfree_bulk(size_t count, void **addrs);
 
 extern void *vmap(struct page **pages, unsigned int count,
 			unsigned long flags, pgprot_t prot);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d5f2a84e488a..a07aa336b05d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2365,6 +2365,37 @@ void vfree(const void *addr)
 }
 EXPORT_SYMBOL(vfree);
 
+/**
+ * vfree_bulk - Release memory allocated by vmalloc()
+ * @count: Number of elements in array
+ * @addrs: Array of elements to be freed
+ *
+ * Free the virtually continuous memory area starting at @addrs[i], as obtained
+ * from one of the vmalloc() family of APIs.  This will usually also free the
+ * physical memory underlying the virtual allocation, but that memory is
+ * reference counted, so it will not be freed until the last user goes away.
+ *
+ * If @addrs[i] is NULL, no operation is performed.
+ *
+ * Context:
+ * Same as for vfree()
+ */
+void vfree_bulk(size_t count, void **addrs)
+{
+	unsigned int i;
+
+	BUG_ON(in_nmi());
+	might_sleep_if(!in_interrupt());
+
+	for (i = 0; i < count; i++) {
+		kmemleak_free(addrs[i]);
+
+		if (addrs[i])
+			__vfree(addrs[i]);
+	}
+}
+EXPORT_SYMBOL(vfree_bulk);
+
 /**
  * vunmap - release virtual mapping obtained by vmap()
  * @addr:   memory base address
-- 
2.20.1