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io-wq: fix handling of NUMA node IDs

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There are several things that can go wrong in the current code on NUMA
systems, especially if not all nodes are online all the time:

 - If the identifiers of the online nodes do not form a single contiguous
   block starting at zero, wq->wqes will be too small, and OOB memory
   accesses will occur e.g. in the loop in io_wq_create().
 - If a node comes online between the call to num_online_nodes() and the
   for_each_node() loop in io_wq_create(), an OOB write will occur.
 - If a node comes online between io_wq_create() and io_wq_enqueue(), a
   lookup is performed for an element that doesn't exist, and an OOB read
   will probably occur.

Fix it by:

 - using nr_node_ids instead of num_online_nodes() for the allocation size;
   nr_node_ids is calculated by setup_nr_node_ids() to be bigger than the
   highest node ID that could possibly come online at some point, even if
   those nodes' identifiers are not a contiguous block
 - creating workers for all possible CPUs, not just all online ones

This is basically what the normal workqueue code also does, as far as I can
tell.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jann Horn 2019-11-26 19:10:20 +01:00 committed by Jens Axboe
parent ad6e005ca6
commit 3fc50ab559
1 changed files with 34 additions and 46 deletions
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80
fs/io-wq.c
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@ -105,7 +105,6 @@ struct io_wqe {
struct io_wq {
struct io_wqe **wqes;
unsigned long state;
unsigned nr_wqes;
get_work_fn *get_work;
put_work_fn *put_work;
@ -632,21 +631,22 @@ static inline bool io_wqe_need_worker(struct io_wqe *wqe, int index)
static int io_wq_manager(void *data)
{
struct io_wq *wq = data;
int i;
int workers_to_create = num_possible_nodes();
int node;
/* create fixed workers */
refcount_set(&wq->refs, wq->nr_wqes);
for (i = 0; i < wq->nr_wqes; i++) {
if (create_io_worker(wq, wq->wqes[i], IO_WQ_ACCT_BOUND))
continue;
goto err;
refcount_set(&wq->refs, workers_to_create);
for_each_node(node) {
if (!create_io_worker(wq, wq->wqes[node], IO_WQ_ACCT_BOUND))
goto err;
workers_to_create--;
}
complete(&wq->done);
while (!kthread_should_stop()) {
for (i = 0; i < wq->nr_wqes; i++) {
struct io_wqe *wqe = wq->wqes[i];
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
bool fork_worker[2] = { false, false };
spin_lock_irq(&wqe->lock);
@ -668,7 +668,7 @@ static int io_wq_manager(void *data)
err:
set_bit(IO_WQ_BIT_ERROR, &wq->state);
set_bit(IO_WQ_BIT_EXIT, &wq->state);
if (refcount_sub_and_test(wq->nr_wqes - i, &wq->refs))
if (refcount_sub_and_test(workers_to_create, &wq->refs))
complete(&wq->done);
return 0;
}
@ -776,7 +776,7 @@ static bool io_wq_for_each_worker(struct io_wqe *wqe,
void io_wq_cancel_all(struct io_wq *wq)
{
int i;
int node;
set_bit(IO_WQ_BIT_CANCEL, &wq->state);
@ -785,8 +785,8 @@ void io_wq_cancel_all(struct io_wq *wq)
* to a worker and the worker putting itself on the busy_list
*/
rcu_read_lock();
for (i = 0; i < wq->nr_wqes; i++) {
struct io_wqe *wqe = wq->wqes[i];
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
io_wq_for_each_worker(wqe, io_wqe_worker_send_sig, NULL);
}
@ -859,10 +859,10 @@ enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
void *data)
{
enum io_wq_cancel ret = IO_WQ_CANCEL_NOTFOUND;
int i;
int node;
for (i = 0; i < wq->nr_wqes; i++) {
struct io_wqe *wqe = wq->wqes[i];
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
ret = io_wqe_cancel_cb_work(wqe, cancel, data);
if (ret != IO_WQ_CANCEL_NOTFOUND)
@ -936,10 +936,10 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
enum io_wq_cancel io_wq_cancel_work(struct io_wq *wq, struct io_wq_work *cwork)
{
enum io_wq_cancel ret = IO_WQ_CANCEL_NOTFOUND;
int i;
int node;
for (i = 0; i < wq->nr_wqes; i++) {
struct io_wqe *wqe = wq->wqes[i];
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
ret = io_wqe_cancel_work(wqe, cwork);
if (ret != IO_WQ_CANCEL_NOTFOUND)
@ -970,10 +970,10 @@ static void io_wq_flush_func(struct io_wq_work **workptr)
void io_wq_flush(struct io_wq *wq)
{
struct io_wq_flush_data data;
int i;
int node;
for (i = 0; i < wq->nr_wqes; i++) {
struct io_wqe *wqe = wq->wqes[i];
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
init_completion(&data.done);
INIT_IO_WORK(&data.work, io_wq_flush_func);
@ -985,15 +985,14 @@ void io_wq_flush(struct io_wq *wq)
struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
{
int ret = -ENOMEM, i, node;
int ret = -ENOMEM, node;
struct io_wq *wq;
wq = kzalloc(sizeof(*wq), GFP_KERNEL);
if (!wq)
return ERR_PTR(-ENOMEM);
wq->nr_wqes = num_online_nodes();
wq->wqes = kcalloc(wq->nr_wqes, sizeof(struct io_wqe *), GFP_KERNEL);
wq->wqes = kcalloc(nr_node_ids, sizeof(struct io_wqe *), GFP_KERNEL);
if (!wq->wqes) {
kfree(wq);
return ERR_PTR(-ENOMEM);
@ -1006,14 +1005,13 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
wq->user = data->user;
wq->creds = data->creds;
i = 0;
for_each_online_node(node) {
for_each_node(node) {
struct io_wqe *wqe;
wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, node);
if (!wqe)
break;
wq->wqes[i] = wqe;
goto err;
wq->wqes[node] = wqe;
wqe->node = node;
wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
atomic_set(&wqe->acct[IO_WQ_ACCT_BOUND].nr_running, 0);
@ -1029,15 +1027,10 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0);
INIT_HLIST_NULLS_HEAD(&wqe->busy_list, 1);
INIT_LIST_HEAD(&wqe->all_list);
i++;
}
init_completion(&wq->done);
if (i != wq->nr_wqes)
goto err;
/* caller must have already done mmgrab() on this mm */
wq->mm = data->mm;
@ -1056,8 +1049,8 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
ret = PTR_ERR(wq->manager);
complete(&wq->done);
err:
for (i = 0; i < wq->nr_wqes; i++)
kfree(wq->wqes[i]);
for_each_node(node)
kfree(wq->wqes[node]);
kfree(wq->wqes);
kfree(wq);
return ERR_PTR(ret);
@ -1071,26 +1064,21 @@ static bool io_wq_worker_wake(struct io_worker *worker, void *data)
void io_wq_destroy(struct io_wq *wq)
{
int i;
int node;
set_bit(IO_WQ_BIT_EXIT, &wq->state);
if (wq->manager)
kthread_stop(wq->manager);
rcu_read_lock();
for (i = 0; i < wq->nr_wqes; i++) {
struct io_wqe *wqe = wq->wqes[i];
if (!wqe)
continue;
io_wq_for_each_worker(wqe, io_wq_worker_wake, NULL);
}
for_each_node(node)
io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL);
rcu_read_unlock();
wait_for_completion(&wq->done);
for (i = 0; i < wq->nr_wqes; i++)
kfree(wq->wqes[i]);
for_each_node(node)
kfree(wq->wqes[node]);
kfree(wq->wqes);
kfree(wq);
}