This is a note to let you know that I've just added the patch titled
Revert "workqueue: Introduce struct wq_node_nr_active"
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
revert-workqueue-introduce-struct-wq_node_nr_active.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fb5e5e004c4c1e3c6f3a209a7d16909d2a9ffac2 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Date: Wed, 3 Apr 2024 16:29:16 +0200
Subject: Revert "workqueue: Introduce struct wq_node_nr_active"
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
This reverts commit 7a5cd14a4900e0017142ad479ba8e34671822fc6 which is
commit 91ccc6e7233bb10a9c176aa4cc70d6f432a441a5 upstream.
The workqueue patches backported to 6.8.y caused some reported
regressions, so revert them for now.
Reported-by: Thorsten Leemhuis <regressions@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Sasha Levin <sashal@xxxxxxxxxx>
Cc: Audra Mitchell <audra@xxxxxxxxxx>
Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@xxxxxxxxxxxxx/
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/workqueue.c | 142 ++---------------------------------------------------
1 file changed, 7 insertions(+), 135 deletions(-)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -281,16 +281,6 @@ struct wq_flusher {
struct wq_device;
/*
- * Unlike in a per-cpu workqueue where max_active limits its concurrency level
- * on each CPU, in an unbound workqueue, max_active applies to the whole system.
- * As sharing a single nr_active across multiple sockets can be very expensive,
- * the counting and enforcement is per NUMA node.
- */
-struct wq_node_nr_active {
- atomic_t nr; /* per-node nr_active count */
-};
-
-/*
* The externally visible workqueue. It relays the issued work items to
* the appropriate worker_pool through its pool_workqueues.
*/
@@ -336,7 +326,6 @@ struct workqueue_struct {
/* hot fields used during command issue, aligned to cacheline */
unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
struct pool_workqueue __percpu __rcu **cpu_pwq; /* I: per-cpu pwqs */
- struct wq_node_nr_active *node_nr_active[]; /* I: per-node nr_active */
};
static struct kmem_cache *pwq_cache;
@@ -1433,31 +1422,6 @@ work_func_t wq_worker_last_func(struct t
}
/**
- * wq_node_nr_active - Determine wq_node_nr_active to use
- * @wq: workqueue of interest
- * @node: NUMA node, can be %NUMA_NO_NODE
- *
- * Determine wq_node_nr_active to use for @wq on @node. Returns:
- *
- * - %NULL for per-cpu workqueues as they don't need to use shared nr_active.
- *
- * - node_nr_active[nr_node_ids] if @node is %NUMA_NO_NODE.
- *
- * - Otherwise, node_nr_active[@node].
- */
-static struct wq_node_nr_active *wq_node_nr_active(struct workqueue_struct *wq,
- int node)
-{
- if (!(wq->flags & WQ_UNBOUND))
- return NULL;
-
- if (node == NUMA_NO_NODE)
- node = nr_node_ids;
-
- return wq->node_nr_active[node];
-}
-
-/**
* get_pwq - get an extra reference on the specified pool_workqueue
* @pwq: pool_workqueue to get
*
@@ -1538,17 +1502,12 @@ static bool pwq_activate_work(struct poo
struct work_struct *work)
{
struct worker_pool *pool = pwq->pool;
- struct wq_node_nr_active *nna;
lockdep_assert_held(&pool->lock);
if (!(*work_data_bits(work) & WORK_STRUCT_INACTIVE))
return false;
- nna = wq_node_nr_active(pwq->wq, pool->node);
- if (nna)
- atomic_inc(&nna->nr);
-
pwq->nr_active++;
__pwq_activate_work(pwq, work);
return true;
@@ -1565,18 +1524,14 @@ static bool pwq_tryinc_nr_active(struct
{
struct workqueue_struct *wq = pwq->wq;
struct worker_pool *pool = pwq->pool;
- struct wq_node_nr_active *nna = wq_node_nr_active(wq, pool->node);
bool obtained;
lockdep_assert_held(&pool->lock);
obtained = pwq->nr_active < READ_ONCE(wq->max_active);
- if (obtained) {
+ if (obtained)
pwq->nr_active++;
- if (nna)
- atomic_inc(&nna->nr);
- }
return obtained;
}
@@ -1613,26 +1568,10 @@ static bool pwq_activate_first_inactive(
static void pwq_dec_nr_active(struct pool_workqueue *pwq)
{
struct worker_pool *pool = pwq->pool;
- struct wq_node_nr_active *nna = wq_node_nr_active(pwq->wq, pool->node);
lockdep_assert_held(&pool->lock);
- /*
- * @pwq->nr_active should be decremented for both percpu and unbound
- * workqueues.
- */
pwq->nr_active--;
-
- /*
- * For a percpu workqueue, it's simple. Just need to kick the first
- * inactive work item on @pwq itself.
- */
- if (!nna) {
- pwq_activate_first_inactive(pwq);
- return;
- }
-
- atomic_dec(&nna->nr);
pwq_activate_first_inactive(pwq);
}
@@ -4087,63 +4026,11 @@ static void wq_free_lockdep(struct workq
}
#endif
-static void free_node_nr_active(struct wq_node_nr_active **nna_ar)
-{
- int node;
-
- for_each_node(node) {
- kfree(nna_ar[node]);
- nna_ar[node] = NULL;
- }
-
- kfree(nna_ar[nr_node_ids]);
- nna_ar[nr_node_ids] = NULL;
-}
-
-static void init_node_nr_active(struct wq_node_nr_active *nna)
-{
- atomic_set(&nna->nr, 0);
-}
-
-/*
- * Each node's nr_active counter will be accessed mostly from its own node and
- * should be allocated in the node.
- */
-static int alloc_node_nr_active(struct wq_node_nr_active **nna_ar)
-{
- struct wq_node_nr_active *nna;
- int node;
-
- for_each_node(node) {
- nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, node);
- if (!nna)
- goto err_free;
- init_node_nr_active(nna);
- nna_ar[node] = nna;
- }
-
- /* [nr_node_ids] is used as the fallback */
- nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, NUMA_NO_NODE);
- if (!nna)
- goto err_free;
- init_node_nr_active(nna);
- nna_ar[nr_node_ids] = nna;
-
- return 0;
-
-err_free:
- free_node_nr_active(nna_ar);
- return -ENOMEM;
-}
-
static void rcu_free_wq(struct rcu_head *rcu)
{
struct workqueue_struct *wq =
container_of(rcu, struct workqueue_struct, rcu);
- if (wq->flags & WQ_UNBOUND)
- free_node_nr_active(wq->node_nr_active);
-
wq_free_lockdep(wq);
free_percpu(wq->cpu_pwq);
free_workqueue_attrs(wq->unbound_attrs);
@@ -4882,8 +4769,7 @@ struct workqueue_struct *alloc_workqueue
{
va_list args;
struct workqueue_struct *wq;
- size_t wq_size;
- int name_len;
+ int len;
/*
* Unbound && max_active == 1 used to imply ordered, which is no longer
@@ -4899,12 +4785,7 @@ struct workqueue_struct *alloc_workqueue
flags |= WQ_UNBOUND;
/* allocate wq and format name */
- if (flags & WQ_UNBOUND)
- wq_size = struct_size(wq, node_nr_active, nr_node_ids + 1);
- else
- wq_size = sizeof(*wq);
-
- wq = kzalloc(wq_size, GFP_KERNEL);
+ wq = kzalloc(sizeof(*wq), GFP_KERNEL);
if (!wq)
return NULL;
@@ -4915,12 +4796,11 @@ struct workqueue_struct *alloc_workqueue
}
va_start(args, max_active);
- name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args);
+ len = vsnprintf(wq->name, sizeof(wq->name), fmt, args);
va_end(args);
- if (name_len >= WQ_NAME_LEN)
- pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n",
- wq->name);
+ if (len >= WQ_NAME_LEN)
+ pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n", wq->name);
max_active = max_active ?: WQ_DFL_ACTIVE;
max_active = wq_clamp_max_active(max_active, flags, wq->name);
@@ -4939,13 +4819,8 @@ struct workqueue_struct *alloc_workqueue
wq_init_lockdep(wq);
INIT_LIST_HEAD(&wq->list);
- if (flags & WQ_UNBOUND) {
- if (alloc_node_nr_active(wq->node_nr_active) < 0)
- goto err_unreg_lockdep;
- }
-
if (alloc_and_link_pwqs(wq) < 0)
- goto err_free_node_nr_active;
+ goto err_unreg_lockdep;
if (wq_online && init_rescuer(wq) < 0)
goto err_destroy;
@@ -4970,9 +4845,6 @@ struct workqueue_struct *alloc_workqueue
return wq;
-err_free_node_nr_active:
- if (wq->flags & WQ_UNBOUND)
- free_node_nr_active(wq->node_nr_active);
err_unreg_lockdep:
wq_unregister_lockdep(wq);
wq_free_lockdep(wq);
Patches currently in stable-queue which might be from gregkh@xxxxxxxxxxxxxxxxxxx are
queue-6.8/revert-workqueue-move-pwq-max_active-to-wq-max_active.patch
queue-6.8/revert-workqueue-replace-pwq_activate_inactive_work-with-pwq_activate_work.patch
queue-6.8/revert-workqueue-implement-system-wide-nr_active-enforcement-for-unbound-workqueues.patch
queue-6.8/revert-workqueue-introduce-struct-wq_node_nr_active.patch
queue-6.8/revert-workqueue-rcu-protect-wq-dfl_pwq-and-implement-accessors-for-it.patch
queue-6.8/revert-workqueue-don-t-call-cpumask_test_cpu-with-1-cpu-in-wq_update_node_max_active.patch
queue-6.8/revert-workqueue-factor-out-pwq_is_empty.patch
queue-6.8/revert-workqueue-shorten-events_freezable_power_efficient-name.patch
queue-6.8/revert-workqueue-make-wq_adjust_max_active-round-robin-pwqs-while-activating.patch
queue-6.8/revert-workqueue.c-increase-workqueue-name-length.patch
queue-6.8/revert-workqueue-move-nr_active-handling-into-helpers.patch
