@@ -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 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(-)