From: Kefeng Wang <wangkefeng.wang@huawei.com>
To: Andrew Morton <akpm@linux-foundation.org>, <linux-mm@kvack.org>
Cc: <muchun.song@linux.dev>, <linux-kernel@vger.kernel.org>,
Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: [PATCH 2/2] mm: slince possible data races about pgdat->kswapd
Date: Wed, 24 Aug 2022 15:19:09 +0800 [thread overview]
Message-ID: <20220824071909.192535-2-wangkefeng.wang@huawei.com> (raw)
In-Reply-To: <20220824071909.192535-1-wangkefeng.wang@huawei.com>
The pgdat->kswapd could be accessed concurrently by kswapd_run() and
kcompactd(), it don't be protected by any lock, which could leads to
data races, adding READ/WRITE_ONCE() to slince it.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
mm/compaction.c | 4 +++-
mm/vmscan.c | 8 ++++----
2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 640fa76228dd..aa1cfe47f046 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1983,7 +1983,9 @@ static inline bool is_via_compact_memory(int order)
static bool kswapd_is_running(pg_data_t *pgdat)
{
- return pgdat->kswapd && task_is_running(pgdat->kswapd);
+ struct task_struct *t = READ_ONCE(pgdat->kswapd);
+
+ return t && task_is_running(t);
}
/*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 08c6497f76c3..65b19ca8c8ee 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4644,7 +4644,7 @@ void kswapd_run(int nid)
pg_data_t *pgdat = NODE_DATA(nid);
struct task_struct *t;
- if (pgdat->kswapd)
+ if (READ_ONCE(pgdat->kswapd))
return;
t = kthread_run(kswapd, pgdat, "kswapd%d", nid);
@@ -4653,7 +4653,7 @@ void kswapd_run(int nid)
BUG_ON(system_state < SYSTEM_RUNNING);
pr_err("Failed to start kswapd on node %d\n", nid);
} else {
- pgdat->kswapd = t;
+ WRITE_ONCE(pgdat->kswapd, t);
}
}
@@ -4663,11 +4663,11 @@ void kswapd_run(int nid)
*/
void kswapd_stop(int nid)
{
- struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
+ struct task_struct *kswapd = READ_ONCE(NODE_DATA(nid)->kswapd);
if (kswapd) {
kthread_stop(kswapd);
- NODE_DATA(nid)->kswapd = NULL;
+ WRITE_ONCE(NODE_DATA(nid)->kswapd, NULL);
}
}
--
2.35.3
next prev parent reply other threads:[~2022-08-24 7:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-24 7:19 [PATCH 1/2] mm: fix null-ptr-deref in kswapd_is_running() Kefeng Wang
2022-08-24 7:19 ` Kefeng Wang [this message]
2022-08-24 8:24 ` [PATCH 2/2] mm: slince possible data races about pgdat->kswapd David Hildenbrand
2022-08-24 9:51 ` Kefeng Wang
2022-08-25 2:34 ` Kefeng Wang
2022-08-25 8:22 ` David Hildenbrand
2022-08-25 9:48 ` Kefeng Wang
2022-08-24 7:56 ` [PATCH 1/2] mm: fix null-ptr-deref in kswapd_is_running() David Hildenbrand
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220824071909.192535-2-wangkefeng.wang@huawei.com \
--to=wangkefeng.wang@huawei.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=muchun.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).