lkml.org 
[lkml]   [2018]   [Apr]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH -mmotm] prctl: add comment about mmap_sem and arg_lock
Date
Add comment to elaborate why mmap_sem for is used by prctl.

Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
---
akpm: this patch can be foled into:
mm-introduce-arg_lock-to-protect-arg_startend-and-env_startend-in-mm_struct.patch

kernel/sys.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/kernel/sys.c b/kernel/sys.c
index 0cc5a1c..943fdc5 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2011,6 +2011,10 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data
return error;
}

+ /*
+ * arg_lock protects concurent updates but we still need mmap_sem for
+ * read to exclude races with sys_brk.
+ */
down_read(&mm->mmap_sem);

/*
--
1.8.3.1
\
 
 \ /
  Last update: 2018-04-18 20:57    [W:0.095 / U:0.392 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site