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@xxxxxxxxxxxxxxx>
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
Signed-off-by: Hongchen Zhang <zhanghongchen@xxxxxxxxxxx>
---
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);
