The patch titled
Subject: mm/kmemleak: rely on rcu for task stack scanning
has been added to the -mm tree. Its filename is
mm-kmemleak-rely-on-rcu-for-task-stack-scanning.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-kmemleak-rely-on-rcu-for-task-stack-scanning.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-kmemleak-rely-on-rcu-for-task-stack-scanning.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: mm/kmemleak: rely on rcu for task stack scanning
kmemleak_scan() currently relies on the big tasklist_lock hammer to
stabilize iterating through the tasklist. Instead, this patch proposes
simply using rcu along with the rcu-safe for_each_process_thread flavor
(without changing scan semantics), which doesn't make use of
next_thread/p->thread_group and thus cannot race with exit. Furthermore,
any races with fork() and not seeing the new child should be benign as
it's not running yet and can also be detected by the next scan.
Link: https://lkml.kernel.org/r/20200820203902.11308-1-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kmemleak.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/kmemleak.c~mm-kmemleak-rely-on-rcu-for-task-stack-scanning
+++ a/mm/kmemleak.c
@@ -1471,15 +1471,15 @@ static void kmemleak_scan(void)
if (kmemleak_stack_scan) {
struct task_struct *p, *g;
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
+ rcu_read_lock();
+ for_each_process_thread(g, p) {
void *stack = try_get_task_stack(p);
if (stack) {
scan_block(stack, stack + THREAD_SIZE, NULL);
put_task_stack(p);
}
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
+ }
+ rcu_read_unlock();
}
/*
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
mm-kmemleak-rely-on-rcu-for-task-stack-scanning.patch
