Hi,
It is due to try to allocate memory with GFP_KERNEL at ISR, below change
can fix it, if not better solution, I can submit a patch.
diff --git a/drivers/usb/gadget/function/f_loopback.c b/drivers/usb/gadget/function/f_loopback.c
index 6b2102b..d2524a1 100644
--- a/drivers/usb/gadget/function/f_loopback.c
+++ b/drivers/usb/gadget/function/f_loopback.c
@@ -329,7 +329,7 @@ static int alloc_requests(struct usb_composite_dev *cdev,
for (i = 0; i < loop->qlen && result == 0; i++) {
result = -ENOMEM;
- in_req = usb_ep_alloc_request(loop->in_ep, GFP_KERNEL);
+ in_req = usb_ep_alloc_request(loop->in_ep, GFP_ATOMIC);
if (!in_req)
goto fail;
------------------Warning Log-----------------------
[ 40.438237] zero gadget: high-speed config #2: loopback
[ 40.444924] ------------[ cut here ]------------
[ 40.449609] WARNING: CPU: 0 PID: 0 at /u/home/b29397/work/projects/usb/kernel/locking/lockdep.c:2755 lockdep_trace_alloc+0x108/0x128()
[ 40.461715] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))
[ 40.467130] Modules linked in:
[ 40.470216] usb_f_ss_lb g_zero libcomposite evbug
[ 40.473822] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.3.0-rc5-00168-gb730aaf #604
[ 40.481496] Hardware name: Freescale i.MX6 SoloX (Device Tree)
[ 40.487345] Backtrace:
[ 40.489857] [<80014e94>] (dump_backtrace) from [<80015088>] (show_stack+0x18/0x1c)
[ 40.497445] r6:80b67a80 r5:00000000 r4:00000000 r3:00000000
[ 40.503234] [<80015070>] (show_stack) from [<802e27b4>] (dump_stack+0x8c/0xa4)
[ 40.510503] [<802e2728>] (dump_stack) from [<8002cfe8>] (warn_slowpath_common+0x80/0xbc)
[ 40.518612] r6:8007510c r5:00000009 r4:80b49c88 r3:00000001
[ 40.524396] [<8002cf68>] (warn_slowpath_common) from [<8002d05c>] (warn_slowpath_fmt+0x38/0x40)
[ 40.533109] r8:bcfdef80 r7:bdb705cc r6:000080d0 r5:be001e80 r4:809cc278
[ 40.539965] [<8002d028>] (warn_slowpath_fmt) from [<8007510c>] (lockdep_trace_alloc+0x108/0x128)
[ 40.548766] r3:809d0128 r2:809cc278
[ 40.552401] r4:600b0193
[ 40.554990] [<80075004>] (lockdep_trace_alloc) from [<801093d4>] (kmem_cache_alloc+0x28/0x15c)
[ 40.563618] r4:000080d0 r3:80b4aa8c
[ 40.567270] [<801093ac>] (kmem_cache_alloc) from [<804d95e4>] (ep_alloc_request+0x58/0x68)
[ 40.575550] r10:7f01f104 r9:00000001 r8:bcfdef80 r7:bdb705cc r6:bc178700 r5:00000000
[ 40.583512] r4:bcfdef80 r3:813c0a38
[ 40.587183] [<804d958c>] (ep_alloc_request) from [<7f01f7ec>] (loopback_set_alt+0x114/0x21c [usb_f_ss_lb])
[ 40.596929] [<7f01f6d8>] (loopback_set_alt [usb_f_ss_lb]) from [<7f006910>] (composite_setup+0xbd0/0x17e8 [libcomposite])
[ 40.607902] r10:bd3a2c0c r9:00000000 r8:bcfdef80 r7:bc178700 r6:bdb702d0 r5:bcfdefdc
[ 40.615866] r4:7f0199b4 r3:00000002
[ 40.619542] [<7f005d40>] (composite_setup [libcomposite]) from [<804dae88>] (udc_irq+0x784/0xd1c)
[ 40.628431] r10:80bb5619 r9:c0876140 r8:00012001 r7:bdb71010 r6:bdb70568 r5:00010001
[ 40.636392] r4:bdb70014
[ 40.638985] [<804da704>] (udc_irq) from [<804d64f8>] (ci_irq+0x5c/0x118)
[ 40.645702] r10:80bb5619 r9:be11e000 r8:00000117 r7:00000000 r6:bdb71010 r5:be11e060
[ 40.653666] r4:bdb70010
[ 40.656261] [<804d649c>] (ci_irq) from [<8007f638>] (handle_irq_event_percpu+0x7c/0x13c)
[ 40.664367] r6:00000000 r5:be11e060 r4:bdb05cc0 r3:804d649c
[ 40.670149] [<8007f5bc>] (handle_irq_event_percpu) from [<8007f740>] (handle_irq_event+0x48/0x6c)
[ 40.679036] r10:00000000 r9:be008000 r8:00000001 r7:00000000 r6:bdb05cc0 r5:be11e060
[ 40.686998] r4:be11e000
[ 40.689581] [<8007f6f8>] (handle_irq_event) from [<80082850>] (handle_fasteoi_irq+0xd4/0x1b0)
[ 40.698120] r6:80b56a30 r5:be11e060 r4:be11e000 r3:00000000
[ 40.703898] [<8008277c>] (handle_fasteoi_irq) from [<8007ec04>] (generic_handle_irq+0x28/0x3c)
[ 40.712524] r7:00000000 r6:80b4aaf4 r5:00000117 r4:80b445fc
[ 40.718304] [<8007ebdc>] (generic_handle_irq) from [<8007ef20>] (__handle_domain_irq+0x6c/0xe8)
[ 40.727033] [<8007eeb4>] (__handle_domain_irq) from [<800095d4>] (gic_handle_irq+0x48/0x94)
[ 40.735402] r9:c080f100 r8:80b4ac6c r7:c080e100 r6:80b67d40 r5:80b49f00 r4:c080e10c
[ 40.743290] [<8000958c>] (gic_handle_irq) from [<80015d38>] (__irq_svc+0x58/0x78)
[ 40.750791] Exception stack(0x80b49f00 to 0x80b49f48)
[ 40.755873] 9f00: 00000001 00000001 00000000 80024320 80b48000 80b4a9d0 80b4a984 80b433e4
[ 40.764078] 9f20: 00000001 807f4680 00000000 80b49f5c 80b49f20 80b49f50 80071ca4 800113fc
[ 40.772272] 9f40: 200b0013 ffffffff
[ 40.775776] r9:807f4680 r8:00000001 r7:80b49f34 r6:ffffffff r5:200b0013 r4:800113fc
[ 40.783677] [<800113d4>] (arch_cpu_idle) from [<8006c5bc>] (default_idle_call+0x28/0x38)
[ 40.791798] [<8006c594>] (default_idle_call) from [<8006c6dc>] (cpu_startup_entry+0x110/0x1b0)
[ 40.800445] [<8006c5cc>] (cpu_startup_entry) from [<807e95dc>] (rest_init+0x12c/0x168)
[ 40.808376] r7:80b4a8c0 r3:807f4b7c
[ 40.812030] [<807e94b0>] (rest_init) from [<80ad7cc0>] (start_kernel+0x360/0x3d4)
[ 40.819528] r5:80bcb000 r4:80bcb050
[ 40.823171] [<80ad7960>] (start_kernel) from [<8000807c>] (0x8000807c)
[ 40.829716] ---[ end trace bee8663a6fecd158 ]---
--
Best Regards,
Peter Chen
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