The patch titled
Subject: kernel/fork.c: annotate data races for copy_process
has been added to the -mm tree. Its filename is
kernel-forkc-annotate-data-races-for-copy_process.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kernel-forkc-annotate-data-races-for-copy_process.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kernel-forkc-annotate-data-races-for-copy_process.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Weilong Chen <chenweilong@xxxxxxxxxx>
Subject: kernel/fork.c: annotate data races for copy_process
The check is only there to stop root fork bombs.
BUG: KCSAN: data-race in copy_process / copy_process
write to 0xffffffff86f87d20 of 4 bytes by task 7121 on cpu 5:
copy_process+0x2e1a/0x3af0 kernel/fork.c:2285
_do_fork+0xf7/0x790 kernel/fork.c:2430
__do_sys_clone+0xf9/0x130 kernel/fork.c:2585
__se_sys_clone kernel/fork.c:2566 [inline]
__x64_sys_clone+0x6c/0x80 kernel/fork.c:2566
do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x44/0xa9
read to 0xffffffff86f87d20 of 4 bytes by task 7125 on cpu 3:
copy_process+0x9eb/0x3af0 kernel/fork.c:1967
_do_fork+0xf7/0x790 kernel/fork.c:2430
__do_sys_clone+0xf9/0x130 kernel/fork.c:2585
__se_sys_clone kernel/fork.c:2566 [inline]
__x64_sys_clone+0x6c/0x80 kernel/fork.c:2566
do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Link: http://lkml.kernel.org/r/20200609030801.272704-1-chenweilong@xxxxxxxxxx
Signed-off-by: Weilong Chen <chenweilong@xxxxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Christian Brauner <christian.brauner@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/fork.c~kernel-forkc-annotate-data-races-for-copy_process
+++ a/kernel/fork.c
@@ -1976,7 +1976,7 @@ static __latent_entropy struct task_stru
* to stop root fork bombs.
*/
retval = -EAGAIN;
- if (nr_threads >= max_threads)
+ if (data_race(nr_threads >= max_threads))
goto bad_fork_cleanup_count;
delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
_
Patches currently in -mm which might be from chenweilong@xxxxxxxxxx are
kernel-forkc-annotate-data-races-for-copy_process.patch
