From: Wei Yang <richardw.yang@linux.intel.com>
To: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com,
akpm@linux-foundation.org
Cc: cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, kirill.shutemov@linux.intel.com,
yang.shi@linux.alibaba.com, alexander.duyck@gmail.com,
rientjes@google.com, Wei Yang <richardw.yang@linux.intel.com>
Subject: [Patch v2] mm: thp: grab the lock before manipulation defer list
Date: Thu, 9 Jan 2020 22:30:54 +0800 [thread overview]
Message-ID: <20200109143054.13203-1-richardw.yang@linux.intel.com> (raw)
As all the other places, we grab the lock before manipulate the defer list.
Current implementation may face a race condition.
For example, the potential race would be:
CPU1 CPU2
mem_cgroup_move_account split_huge_page_to_list
!list_empty
lock
!list_empty
list_del
unlock
lock
# !list_empty might not hold anymore
list_del_init
unlock
When this sequence happens, the list_del_init() in
mem_cgroup_move_account() would crash if CONFIG_DEBUG_LIST since the
page is already been removed by list_del in split_huge_page_to_list().
Fixes: 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware")
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: David Rientjes <rientjes@google.com>
---
v2:
* move check on compound outside suggested by Alexander
* an example of the race condition, suggested by Michal
---
mm/memcontrol.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bc01423277c5..1492eefe4f3c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5368,10 +5368,12 @@ static int mem_cgroup_move_account(struct page *page,
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- if (compound && !list_empty(page_deferred_list(page))) {
+ if (compound) {
spin_lock(&from->deferred_split_queue.split_queue_lock);
- list_del_init(page_deferred_list(page));
- from->deferred_split_queue.split_queue_len--;
+ if (!list_empty(page_deferred_list(page))) {
+ list_del_init(page_deferred_list(page));
+ from->deferred_split_queue.split_queue_len--;
+ }
spin_unlock(&from->deferred_split_queue.split_queue_lock);
}
#endif
@@ -5385,11 +5387,13 @@ static int mem_cgroup_move_account(struct page *page,
page->mem_cgroup = to;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- if (compound && list_empty(page_deferred_list(page))) {
+ if (compound) {
spin_lock(&to->deferred_split_queue.split_queue_lock);
- list_add_tail(page_deferred_list(page),
- &to->deferred_split_queue.split_queue);
- to->deferred_split_queue.split_queue_len++;
+ if (list_empty(page_deferred_list(page))) {
+ list_add_tail(page_deferred_list(page),
+ &to->deferred_split_queue.split_queue);
+ to->deferred_split_queue.split_queue_len++;
+ }
spin_unlock(&to->deferred_split_queue.split_queue_lock);
}
#endif
--
2.17.1
next reply other threads:[~2020-01-09 14:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-09 14:30 Wei Yang [this message]
2020-01-09 18:52 ` [Patch v2] mm: thp: grab the lock before manipulation defer list David Rientjes
2020-01-09 18:58 ` Michal Hocko
2020-01-11 0:03 ` Kirill A. Shutemov
2020-01-12 2:28 ` Wei Yang
2020-01-12 22:57 ` Kirill A. Shutemov
2020-01-13 0:44 ` Wei Yang
2020-01-13 7:36 ` Kirill A. Shutemov
2020-01-13 8:23 ` Wei Yang
2020-01-14 9:31 ` Michal Hocko
2020-01-14 10:31 ` Kirill A. Shutemov
2020-01-14 10:59 ` Kirill A. Shutemov
2020-01-14 20:57 ` David Rientjes
2020-01-15 1:19 ` Wei Yang
2020-01-15 1:07 ` Wei Yang
2020-01-15 3:26 ` David Rientjes
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=20200109143054.13203-1-richardw.yang@linux.intel.com \
--to=richardw.yang@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=alexander.duyck@gmail.com \
--cc=cgroups@vger.kernel.org \
--cc=hannes@cmpxchg.org \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=rientjes@google.com \
--cc=vdavydov.dev@gmail.com \
--cc=yang.shi@linux.alibaba.com \
/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