@@ -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
The patch titled Subject: mm: thp: grab the lock before manipulating defer list has been removed from the -mm tree. Its filename was mm-thp-grab-the-lock-before-manipulation-defer-list.patch This patch was dropped because an updated version will be merged ------------------------------------------------------ From: Wei Yang <richardw.yang@linux.intel.com> Subject: mm: thp: grab the lock before manipulating defer list 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 deferred_split_huge_page list_empty lock list_empty list_add_tail unlock lock # list_empty might not hold anymore list_add_tail unlock When this sequence happens, the list_add_tail() in mem_cgroup_move_account() corrupt the list since which is already been added to some split_queue in split_huge_page_to_list(). Besides this, David Rientjes points out the split_queue_len would be in a wrong state, which would be a significant issue for shrinkers. 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> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.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(-)