Cache size can grow or shrink due to various pressures at
any time. So when we resize the cache as part of a 'grow'
operation (i.e. change the size to allow more devices) we need
to blocks that automatic growing/shrinking.
So introduce a mutex. auto grow/shrink uses mutex_trylock()
and just doesn't bother if there is a blockage.
Resizing the whole cache holds the mutex to ensure that
the correct number of new stripes is allocated.
This bug can result in some stripes not being freed when an
array is stopped. This leads to the kmem_cache not being
freed and a subsequent array can try to use the same kmem_cache
and get confused.
Fixes: edbe83ab4c27 ("md/raid5: allow the stripe_cache to grow and shrink.")
Cc: stable@vger.kernel.org (4.1 - please delay until 2 weeks after release of 4.2)
Signed-off-by: NeilBrown <neilb@suse.com>
+ /* Need to ensure auto-resizing doesn't interfere */
+ mutex_lock(&conf->cache_size_mutex);
+
for (i = conf->max_nr_stripes; i; i--) {
nsh = alloc_stripe(sc, GFP_KERNEL);
if (!nsh)
for (i = conf->max_nr_stripes; i; i--) {
nsh = alloc_stripe(sc, GFP_KERNEL);
if (!nsh)
kmem_cache_free(sc, nsh);
}
kmem_cache_destroy(sc);
kmem_cache_free(sc, nsh);
}
kmem_cache_destroy(sc);
+ mutex_unlock(&conf->cache_size_mutex);
return -ENOMEM;
}
/* Step 2 - Must use GFP_NOIO now.
return -ENOMEM;
}
/* Step 2 - Must use GFP_NOIO now.
+ mutex_unlock(&conf->cache_size_mutex);
/* Step 4, return new stripes to service */
while(!list_empty(&newstripes)) {
nsh = list_entry(newstripes.next, struct stripe_head, lru);
/* Step 4, return new stripes to service */
while(!list_empty(&newstripes)) {
nsh = list_entry(newstripes.next, struct stripe_head, lru);
pr_debug("%d stripes handled\n", handled);
spin_unlock_irq(&conf->device_lock);
pr_debug("%d stripes handled\n", handled);
spin_unlock_irq(&conf->device_lock);
- if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state)) {
+ if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
+ mutex_trylock(&conf->cache_size_mutex)) {
grow_one_stripe(conf, __GFP_NOWARN);
/* Set flag even if allocation failed. This helps
* slow down allocation requests when mem is short
*/
set_bit(R5_DID_ALLOC, &conf->cache_state);
grow_one_stripe(conf, __GFP_NOWARN);
/* Set flag even if allocation failed. This helps
* slow down allocation requests when mem is short
*/
set_bit(R5_DID_ALLOC, &conf->cache_state);
+ mutex_unlock(&conf->cache_size_mutex);
}
async_tx_issue_pending_all();
}
async_tx_issue_pending_all();
return -EINVAL;
conf->min_nr_stripes = size;
return -EINVAL;
conf->min_nr_stripes = size;
+ mutex_lock(&conf->cache_size_mutex);
while (size < conf->max_nr_stripes &&
drop_one_stripe(conf))
;
while (size < conf->max_nr_stripes &&
drop_one_stripe(conf))
;
+ mutex_unlock(&conf->cache_size_mutex);
err = md_allow_write(mddev);
if (err)
return err;
err = md_allow_write(mddev);
if (err)
return err;
+ mutex_lock(&conf->cache_size_mutex);
while (size > conf->max_nr_stripes)
if (!grow_one_stripe(conf, GFP_KERNEL))
break;
while (size > conf->max_nr_stripes)
if (!grow_one_stripe(conf, GFP_KERNEL))
break;
+ mutex_unlock(&conf->cache_size_mutex);
struct shrink_control *sc)
{
struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
struct shrink_control *sc)
{
struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
- int ret = 0;
- while (ret < sc->nr_to_scan) {
- if (drop_one_stripe(conf) == 0)
- return SHRINK_STOP;
- ret++;
+ unsigned long ret = SHRINK_STOP;
+
+ if (mutex_trylock(&conf->cache_size_mutex)) {
+ ret= 0;
+ while (ret < sc->nr_to_scan) {
+ if (drop_one_stripe(conf) == 0) {
+ ret = SHRINK_STOP;
+ break;
+ }
+ ret++;
+ }
+ mutex_unlock(&conf->cache_size_mutex);
goto abort;
spin_lock_init(&conf->device_lock);
seqcount_init(&conf->gen_lock);
goto abort;
spin_lock_init(&conf->device_lock);
seqcount_init(&conf->gen_lock);
+ mutex_init(&conf->cache_size_mutex);
init_waitqueue_head(&conf->wait_for_quiescent);
for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++) {
init_waitqueue_head(&conf->wait_for_stripe[i]);
init_waitqueue_head(&conf->wait_for_quiescent);
for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++) {
init_waitqueue_head(&conf->wait_for_stripe[i]);
*/
int active_name;
char cache_name[2][32];
*/
int active_name;
char cache_name[2][32];
- struct kmem_cache *slab_cache; /* for allocating stripes */
+ struct kmem_cache *slab_cache; /* for allocating stripes */
+ struct mutex cache_size_mutex; /* Protect changes to cache size */
int seq_flush, seq_write;
int quiesce;
int seq_flush, seq_write;
int quiesce;