* + mm-thp-grab-the-lock-before-manipulation-defer-list.patch added to -mm tree
@ 2020-01-09 19:49 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2020-01-09 19:49 UTC (permalink / raw)
To: hannes, mhocko, mm-commits, richardw.yang, rientjes, stable,
vdavydov.dev
The patch titled
Subject: mm: thp: grab the lock before manipulation defer list
has been added to the -mm tree. Its filename is
mm-thp-grab-the-lock-before-manipulation-defer-list.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-grab-the-lock-before-manipulation-defer-list.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-grab-the-lock-before-manipulation-defer-list.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** 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: Wei Yang <richardw.yang@linux.intel.com>
Subject: mm: thp: grab the lock before manipulation defer list
As in all the other places, we grab the lock before manipulating 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().
Link: http://lkml.kernel.org/r/20200109143054.13203-1-richardw.yang@linux.intel.com
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>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org> [5.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/memcontrol.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
--- a/mm/memcontrol.c~mm-thp-grab-the-lock-before-manipulation-defer-list
+++ a/mm/memcontrol.c
@@ -5341,10 +5341,12 @@ static int mem_cgroup_move_account(struc
}
#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
@@ -5358,11 +5360,13 @@ static int mem_cgroup_move_account(struc
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
_
Patches currently in -mm which might be from richardw.yang@linux.intel.com are
mm-thp-grab-the-lock-before-manipulation-defer-list.patch
mm-remove-dead-code-totalram_pages_set.patch
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2020-01-09 19:49 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-09 19:49 + mm-thp-grab-the-lock-before-manipulation-defer-list.patch added to -mm tree akpm
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).