mm: document locking restrictions for vm_operations_struct::close

Add comments for vm_operations_struct::close documenting locking
requirements for this callback and its callers.

Link: https://lkml.kernel.org/r/20211209191325.3069345-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Brauner <christian@brauner.io>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jan Engelhardt <jengelh@inai.de>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tim Murray <timmurray@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c17e5cfc1e4726f74f7d28c238714909f3b67b2c..4d7245e6802a6582e236a1baf2c0a15e94c29f5f 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -532,6 +532,10 @@ enum page_entry_size {
  */
 struct vm_operations_struct {
        void (*open)(struct vm_area_struct * area);
+       /**
+        * @close: Called when the VMA is being removed from the MM.
+        * Context: User context.  May sleep.  Caller holds mmap_lock.
+        */
        void (*close)(struct vm_area_struct * area);
        /* Called any time before splitting to check if it's allowed */
        int (*may_split)(struct vm_area_struct *area, unsigned long addr);