[PATCH 01/11] mm: update the documentation for vfree

From: Christoph Hellwig
Date: Fri Oct 02 2020 - 08:23:13 EST


From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>

* 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@xxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
mm/vmalloc.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index be4724b916b3e7..8770260419af06 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2321,20 +2321,21 @@ 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.
+ * Free the virtually continuous memory area starting at @addr, 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.
*
- * 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)
+ * 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