linux-kernel - [PATCH 2/2] vfree: Update documentation

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Message-Id: <20200921224628.20704-2-willy@infradead.org>
Date:   Mon, 21 Sep 2020 23:46:28 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org, hch@....de,
        Uladzislau Rezki <urezki@...il.com>
Subject: [PATCH 2/2] vfree: Update documentation

 * Document that you can call vfree() on an address returned from vmap()
 * Remove the note about the minimum size -- the minimum size of a vmalloc
   allocation is one page
 * Add a Context: section
 * Fix capitalisation
 * Reword the prohibition on calling from NMI context to avoid a double
   negative

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 mm/vmalloc.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 3893fc8915c4..942a44bdeec6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2313,20 +2313,20 @@ static void __vfree(const void *addr)
 }
 
 /**
- * vfree - release memory allocated by vmalloc()
- * @addr:  memory base address
+ * vfree - Release memory allocated by vmalloc()
+ * @addr:  Memory base address
  *
  * Free the virtually continuous memory area starting at @addr, as
- * obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
- * NULL, no operation is performed.
- *
- * Must not be called in NMI context (strictly speaking, only if we don't
- * have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
- * conventions for vfree() arch-depenedent would be a really bad idea)
+ * obtained from vmalloc(), vmalloc_32() or __vmalloc().  If called
+ * on an @addr obtained from vmap(), it will put one refcount on each
+ * mapped page, which will free the page if this is the last refcount
+ * on the page.  If @addr is NULL, no operation is performed.
  *
+ * Context:
  * May sleep if called *not* from interrupt context.
- *
- * NOTE: assumes that the object at @addr has a size >= sizeof(llist_node)
+ * Must not be called in NMI context (strictly speaking, it could be
+ * if we have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
+ * conventions for vfree() arch-depenedent would be a really bad idea).
  */
 void vfree(const void *addr)
 {
-- 
2.28.0