The patch titled
Subject: mm: clarify mm_struct.mm_{users,count} documentation
has been added to the -mm tree. Its filename is
mm-clarify-mm_structmm_userscount-documentation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-clarify-mm_structmm_userscount-documentation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-clarify-mm_structmm_userscount-documentation.patch
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------------------------------------------------------
From: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Subject: mm: clarify mm_struct.mm_{users,count} documentation
Clarify documentation relating to mm_users and mm_count, and switch to
kernel-doc syntax.
Link: http://lkml.kernel.org/r/20161218123229.22952-4-vegard.nossum@xxxxxxxxxx
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm_types.h | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff -puN include/linux/mm_types.h~mm-clarify-mm_structmm_userscount-documentation include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-clarify-mm_structmm_userscount-documentation
+++ a/include/linux/mm_types.h
@@ -407,8 +407,27 @@ struct mm_struct {
unsigned long task_size; /* size of task vm space */
unsigned long highest_vm_end; /* highest vma end address */
pgd_t * pgd;
- atomic_t mm_users; /* How many users with user space? */
- atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */
+
+ /**
+ * @mm_users: The number of users including userspace.
+ *
+ * Use mmget()/mmget_not_zero()/mmput() to modify. When this drops
+ * to 0 (i.e. when the task exits and there are no other temporary
+ * reference holders), we also release a reference on @mm_count
+ * (which may then free the &struct mm_struct if @mm_count also
+ * drops to 0).
+ */
+ atomic_t mm_users;
+
+ /**
+ * @mm_count: The number of references to &struct mm_struct
+ * (@mm_users count as 1).
+ *
+ * Use mmgrab()/mmdrop() to modify. When this drops to 0, the
+ * &struct mm_struct is freed.
+ */
+ atomic_t mm_count;
+
atomic_long_t nr_ptes; /* PTE page table pages */
#if CONFIG_PGTABLE_LEVELS > 2
atomic_long_t nr_pmds; /* PMD page table pages */
_
Patches currently in -mm which might be from vegard.nossum@xxxxxxxxxx are
mm-add-new-mmgrab-helper.patch
mm-add-new-mmget-helper.patch
mm-use-mmget_not_zero-helper.patch
mm-clarify-mm_structmm_userscount-documentation.patch
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