Re: Panic when make check for ndctl

[Dan Williams <dan.j.williams@intel.com>]

On Tue, Jun 13, 2017 at 7:41 PM, Yasunori Goto <y-goto@jp.fujitsu.com> wrote:
> Hi, Dan-san, Linda-san,
>
> I had chased the root cause of this panic problem, and maybe I found it.
>
>> > > Hmmm, though I made Fedora 25 environment, this panic still occurs...
>> > > I'll attach syslog and .config again.
>> > >
>> > >
>> > [..]
>> > > [  117.804948] general protection fault: 0000 [#1] SMP
>> > [..]
>> > > [  117.820866] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>> > [..]
>> > > [  117.843262] Call Trace:
>> > > [  117.843985]  release_nodes+0x76/0x260
>> > > [  117.845062]  devres_release_all+0x3c/0x50
>> > > [  117.846225]  device_release_driver_internal+0x159/0x200
>> > > [  117.847748]  device_release_driver+0x12/0x20
>> > > [  117.849029]  bus_remove_device+0xfd/0x170
>> > > [  117.850192]  device_del+0x1e8/0x330
>> > > [  117.851284]  platform_device_del+0x28/0x90
>> > > [  117.852485]  platform_device_unregister+0x12/0x30
>> > > [  117.853846]  nfit_test_exit+0x2a/0x93b [nfit_test]
>> > > [  117.855219]  SyS_delete_module+0x171/0x250
>> > > [  117.856403]  entry_SYSCALL_64_fastpath+0x1a/0xa5
>> >
>> > Can you also attach the qemu-kvm command line you are using?
>> >
>> >     ps aux | grep qemu
>
>
> The cause of this problem is the num_pm of nfit_test1 is wrong.
> Though 1 is specified for num_pm at nfit_test_init(), it must be 2.
>
> ----
> static __init int nfit_test_init(void)
> {
>         int rc, i;
>         :
>         :
>                 case 1:
>                         nfit_test->num_pm = 1;            <---- !!!
>                         nfit_test->dcr_idx = NUM_DCR;
> -----
>
> The num_pm affects size of devm_kcalloc() at nfit_test_probe().
>
> ----
> static int nfit_test_probe(struct platform_device *pdev)
> {
>         if (nfit_test->num_pm) {
>                 int num = nfit_test->num_pm;   <----!!!
>
>                 nfit_test->spa_set = devm_kcalloc(dev, num, sizeof(void *),
>                                 GFP_KERNEL);   <---!!!!
>                 nfit_test->spa_set_dma = devm_kcalloc(dev, num,
>                                 sizeof(dma_addr_t), GFP_KERNEL);
> -----
>
> However,  spa_set[] array needs 2 elements at nfit_test1_alloc().
>
> ---
> static int nfit_test1_alloc(struct nfit_test *t)
> {
>                :
>         t->spa_set[0] = test_alloc(t, SPA2_SIZE, &t->spa_set_dma[0]);  <--- first element
>         if (!t->spa_set[0])
>                 return -ENOMEM;
>                :
>
>        t->spa_set[1] = test_alloc(t, SPA_VCD_SIZE, &t->spa_set_dma[1]);  <---- The second element!!!!
> -----
>
> This breaks other area, and the area is often the link list of devres.
> As a result, the panic occured on release_nodes().
>
> I confirmed that this panic never occurred with the following patch.

Care to resend this as a formal patch with a "Signed-off-by:"? I'll
get it applied.
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