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authorLai Jiangshan <jiangshan.ljs@antgroup.com>2024-09-12 11:23:29 +0800
committerTejun Heo <tj@kernel.org>2024-09-11 19:58:20 -1000
commit73613840a8896f4f859eea489cb4a7a656939e70 (patch)
treec0fda9bfaa8bdb419ba7412fdb2c0ba33776ecf3 /kernel
parentc4c8f369b6a6d21ce27286de1501137771e01dc3 (diff)
workqueue: Clear worker->pool in the worker thread context
Marc Hartmayer reported: [ 23.133876] Unable to handle kernel pointer dereference in virtual kernel address space [ 23.133950] Failing address: 0000000000000000 TEID: 0000000000000483 [ 23.133954] Fault in home space mode while using kernel ASCE. [ 23.133957] AS:000000001b8f0007 R3:0000000056cf4007 S:0000000056cf3800 P:000000000000003d [ 23.134207] Oops: 0004 ilc:2 [#1] SMP (snip) [ 23.134516] Call Trace: [ 23.134520] [<0000024e326caf28>] worker_thread+0x48/0x430 [ 23.134525] ([<0000024e326caf18>] worker_thread+0x38/0x430) [ 23.134528] [<0000024e326d3a3e>] kthread+0x11e/0x130 [ 23.134533] [<0000024e3264b0dc>] __ret_from_fork+0x3c/0x60 [ 23.134536] [<0000024e333fb37a>] ret_from_fork+0xa/0x38 [ 23.134552] Last Breaking-Event-Address: [ 23.134553] [<0000024e333f4c04>] mutex_unlock+0x24/0x30 [ 23.134562] Kernel panic - not syncing: Fatal exception: panic_on_oops With debuging and analysis, worker_thread() accesses to the nullified worker->pool when the newly created worker is destroyed before being waken-up, in which case worker_thread() can see the result detach_worker() reseting worker->pool to NULL at the begining. Move the code "worker->pool = NULL;" out from detach_worker() to fix the problem. worker->pool had been designed to be constant for regular workers and changeable for rescuer. To share attaching/detaching code for regular and rescuer workers and to avoid worker->pool being accessed inadvertently when the worker has been detached, worker->pool is reset to NULL when detached no matter the worker is rescuer or not. To maintain worker->pool being reset after detached, move the code "worker->pool = NULL;" in the worker thread context after detached. It is either be in the regular worker thread context after PF_WQ_WORKER is cleared or in rescuer worker thread context with wq_pool_attach_mutex held. So it is safe to do so. Cc: Marc Hartmayer <mhartmay@linux.ibm.com> Link: https://lore.kernel.org/lkml/87wmjj971b.fsf@linux.ibm.com/ Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com> Fixes: f4b7b53c94af ("workqueue: Detach workers directly in idle_cull_fn()") Cc: stable@vger.kernel.org # v6.11+ Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/workqueue.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index e7b005ff3750..6f2545037e57 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2709,7 +2709,6 @@ static void detach_worker(struct worker *worker)
unbind_worker(worker);
list_del(&worker->node);
- worker->pool = NULL;
}
/**
@@ -2729,6 +2728,7 @@ static void worker_detach_from_pool(struct worker *worker)
mutex_lock(&wq_pool_attach_mutex);
detach_worker(worker);
+ worker->pool = NULL;
mutex_unlock(&wq_pool_attach_mutex);
/* clear leftover flags without pool->lock after it is detached */
@@ -3349,7 +3349,11 @@ woke_up:
if (unlikely(worker->flags & WORKER_DIE)) {
raw_spin_unlock_irq(&pool->lock);
set_pf_worker(false);
-
+ /*
+ * The worker is dead and PF_WQ_WORKER is cleared, worker->pool
+ * shouldn't be accessed, reset it to NULL in case otherwise.
+ */
+ worker->pool = NULL;
ida_free(&pool->worker_ida, worker->id);
return 0;
}