From: Johannes Weiner hannes@cmpxchg.org
commit 8c2c2358b236530bc2c79b4c2a447cbdbc3d96d7 upstream.
When charging socket memory, the code currently checks only the local page counter for excess to determine whether the memcg is under socket pressure. But even if the local counter is fine, one of the ancestors could have breached its limit, which should also force this child to enter socket pressure. This currently doesn't happen.
Fix this by using page_counter_try_charge() first. If that fails, it means that either the local counter or one of the ancestors are in excess of their limit, and the child should enter socket pressure.
Fixes: 3e32cb2e0a12 ("mm: memcontrol: lockless page counters") Signed-off-by: Johannes Weiner hannes@cmpxchg.org Acked-by: David S. Miller davem@davemloft.net Reviewed-by: Vladimir Davydov vdavydov@virtuozzo.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/net/sock.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
--- a/include/net/sock.h +++ b/include/net/sock.h @@ -1204,11 +1204,13 @@ static inline void memcg_memory_allocate unsigned long amt, int *parent_status) { - page_counter_charge(&prot->memory_allocated, amt); + struct page_counter *counter; + + if (page_counter_try_charge(&prot->memory_allocated, amt, &counter)) + return;
- if (page_counter_read(&prot->memory_allocated) > - prot->memory_allocated.limit) - *parent_status = OVER_LIMIT; + page_counter_charge(&prot->memory_allocated, amt); + *parent_status = OVER_LIMIT; }
static inline void memcg_memory_allocated_sub(struct cg_proto *prot,