[PATCH] mm: madvise: add description for MADV_WIPEONFORK and MADV_KEEPONFORK

From: Yang Shi
Date: Fri Sep 22 2017 - 17:55:46 EST


mm/madvise.c has the brief description about all MADV_ flags, added the
description for the newly added MADV_WIPEONFORK and MADV_KEEPONFORK.

Although man page has the similar information, but it'd better to keep the
consistency with other flags.

Signed-off-by: Yang Shi <yang.s@xxxxxxxxxxxxxxx>
---
mm/madvise.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 21261ff..c6bf572 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -749,6 +749,9 @@ static int madvise_inject_error(int behavior,
* MADV_DONTFORK - omit this area from child's address space when forking:
* typically, to avoid COWing pages pinned by get_user_pages().
* MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
+ * MADV_WIPEONFORK - present the child process with zero-filled memory in this
+ * range after a fork.
+ * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
* MADV_HWPOISON - trigger memory error handler as if the given memory range
* were corrupted by unrecoverable hardware memory failure.
* MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
@@ -769,7 +772,9 @@ static int madvise_inject_error(int behavior,
* zero - success
* -EINVAL - start + len < 0, start is not page-aligned,
* "behavior" is not a valid value, or application
- * is attempting to release locked or shared pages.
+ * is attempting to release locked or shared pages,
+ * or the specified address range includes file, Huge TLB,
+ * MAP_SHARED or VMPFNMAP range.
* -ENOMEM - addresses in the specified range are not currently
* mapped, or are outside the AS of the process.
* -EIO - an I/O error occurred while paging in data.
--
1.8.3.1