On 7/24/2024 9:58 AM, Hongchen Zhang wrote:
Hi Ethan, On 2024/7/22 PM 3:39, Ethan Zhao wrote:
On 6/13/2024 3:42 PM, Hongchen Zhang wrote:
Call work_on_cpu(cpu, fn, arg) in pci_call_probe() while the argument @cpu is a offline cpu would cause system stuck forever.
This can be happen if a node is online while all its CPUs are offline (We can use "maxcpus=1" without "nr_cpus=1" to reproduce it).
So, in the above case, let pci_call_probe() call local_pci_probe() instead of work_on_cpu() when the best selected cpu is offline.
Fixes: 69a18b18699b ("PCI: Restrict probe functions to housekeeping CPUs") Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Hongchen Zhang zhanghongchen@loongson.cn
v2 -> v3: Modify commit message according to Markus's suggestion v1 -> v2: Add a method to reproduce the problem
drivers/pci/pci-driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index af2996d0d17f..32a99828e6a3 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -386,7 +386,7 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev, free_cpumask_var(wq_domain_mask); } - if (cpu < nr_cpu_ids)
Why not choose the right cpu to callwork_on_cpu() ? the one that is online. Thanks, Ethan
Yes, let housekeeping_cpumask() return online cpu is a good idea, but it may be changed by command line. so the simplest way is to call local_pci_probe when the best selected cpu is offline.
Hmm..... housekeeping_cpumask() should never return offline CPU, so I guess you didn't hit issue with the CPU isolation, but the following code seems not good.
...
if (node < 0 || node >= MAX_NUMNODES || !node_online(node) || pci_physfn_is_probed(dev)) { cpu = nr_cpu_ids; } else {
....
perhaps you could change the logic there and fix it ?
Thanks Ethan
+ if ((cpu < nr_cpu_ids) && cpu_online(cpu)) error = work_on_cpu(cpu, local_pci_probe, &ddi); else error = local_pci_probe(&ddi);