Hello Sarah, On Fri 11-10-13 15:13:15, Sarah Sharp wrote: > I'm testing out some changes to the xHCI USB host controller driver > (which uses a radix tree when a UAS device is attached to the host), and > I noticed the following warning: > > Oct 11 14:42:08 xanatos kernel: [18165.819014] usb 2-2: new SuperSpeed USB device number 2 using xhci_hcd > Oct 11 14:42:08 xanatos kernel: [18165.836264] usb 2-2: New USB device found, idVendor=174c, idProduct=55aa > Oct 11 14:42:08 xanatos kernel: [18165.836271] usb 2-2: New USB device strings: Mfr=2, Product=3, SerialNumber=1 > Oct 11 14:42:08 xanatos kernel: [18165.836275] usb 2-2: Product: Plugable USB3-SATA-UASP1 > Oct 11 14:42:08 xanatos kernel: [18165.836279] usb 2-2: Manufacturer: ASM1053E > Oct 11 14:42:08 xanatos kernel: [18165.836291] usb 2-2: SerialNumber: 123456789045 > Oct 11 14:42:08 xanatos kernel: [18165.847661] BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/8759 > Oct 11 14:42:08 xanatos kernel: [18165.847667] caller is radix_tree_node_alloc+0x5c/0xa0 Well, this warning seems to come from the __get_cpu_var() function. I don't see how my commit could have caused what you observe. It seems you are calling radix_tree_insert() for a radix tree which has atomic gfp mask set and you don't do radix_tree_preload() / radix_tree_preload_end() around that? That was always problematic and could lead to the above warning. I'm not sure in which contexts xhci_update_stream_ring() can be called. But if you are guaranteed non-atomic context, then using radix_tree_preload() with a more relaxed gfp mask is good (lowers pressure on atomic allocations). If the context depends on the caller, things are more complex. Generally, you can use radix_tree_maybe_preload() but you have to set gfp mask argument according to the context. The function then figures out whether it's worth it to do a preload or not (but it always does preempt_disable() which will silence the warning). Honza > Oct 11 14:42:08 xanatos kernel: [18165.847670] CPU: 1 PID: 8759 Comm: modprobe Not tainted 3.12.0-rc4+ #94 > Oct 11 14:42:08 xanatos kernel: [18165.847671] Hardware name: LENOVO 2325AP7/2325AP7, BIOS G2ET82WW (2.02 ) 09/11/2012 > Oct 11 14:42:08 xanatos kernel: [18165.847673] ffff88010c1d3fd8 ffff88010c1d38e8 ffffffff816081b9 0000000000000007 > Oct 11 14:42:08 xanatos kernel: [18165.847677] 0000000000000001 ffff88010c1d3918 ffffffff812e3ffc ffff88010c26c988 > Oct 11 14:42:08 xanatos kernel: [18165.847679] 0000000000000020 00000000000240b1 0000000000000003 ffff88010c1d3938 > Oct 11 14:42:08 xanatos kernel: [18165.847682] Call Trace: > Oct 11 14:42:08 xanatos kernel: [18165.847686] [<ffffffff816081b9>] dump_stack+0x4f/0x84 > Oct 11 14:42:08 xanatos kernel: [18165.847689] [<ffffffff812e3ffc>] debug_smp_processor_id+0xdc/0x100 > Oct 11 14:42:08 xanatos kernel: [18165.847692] [<ffffffff812d47fc>] radix_tree_node_alloc+0x5c/0xa0 > Oct 11 14:42:08 xanatos kernel: [18165.847695] [<ffffffff812d48d5>] radix_tree_insert+0x95/0x260 > Oct 11 14:42:08 xanatos kernel: [18165.847702] [<ffffffffa008446f>] xhci_update_stream_ring+0x8f/0xc0 [xhci_hcd] > Oct 11 14:42:08 xanatos kernel: [18165.847708] [<ffffffffa00860f0>] xhci_alloc_stream_info+0x190/0x410 [xhci_hcd] > Oct 11 14:42:08 xanatos kernel: [18165.847713] [<ffffffffa00802ef>] xhci_alloc_streams+0x36f/0x750 [xhci_hcd] > Oct 11 14:42:08 xanatos kernel: [18165.847716] [<ffffffff8108678f>] ? ttwu_stat+0xef/0x160 > Oct 11 14:42:08 xanatos kernel: [18165.847720] [<ffffffff810c8e93>] ? is_module_address+0x33/0x60 > Oct 11 14:42:08 xanatos kernel: [18165.847729] [<ffffffffa0036e35>] usb_alloc_streams+0x95/0xb0 [usbcore] > Oct 11 14:42:08 xanatos kernel: [18165.847732] [<ffffffffa01eb874>] uas_configure_endpoints+0x154/0x210 [uas] > Oct 11 14:42:08 xanatos kernel: [18165.847735] [<ffffffffa01ec367>] uas_probe+0x2d7/0x390 [uas] > Oct 11 14:42:08 xanatos kernel: [18165.847743] [<ffffffffa0040053>] usb_probe_interface+0x1c3/0x2f0 [usbcore] > Oct 11 14:42:08 xanatos kernel: [18165.847746] [<ffffffff813ba421>] driver_probe_device+0x91/0x3c0 > Oct 11 14:42:08 xanatos kernel: [18165.847749] [<ffffffff813ba7fb>] __driver_attach+0xab/0xb0 > Oct 11 14:42:08 xanatos kernel: [18165.847751] [<ffffffff813ba750>] ? driver_probe_device+0x3c0/0x3c0 > Oct 11 14:42:08 xanatos kernel: [18165.847753] [<ffffffff813b835e>] bus_for_each_dev+0x5e/0x90 > Oct 11 14:42:08 xanatos kernel: [18165.847756] [<ffffffff813b9e6e>] driver_attach+0x1e/0x20 > Oct 11 14:42:08 xanatos kernel: [18165.847758] [<ffffffff813b988f>] bus_add_driver+0x10f/0x2d0 > Oct 11 14:42:08 xanatos kernel: [18165.847760] [<ffffffff813baf24>] driver_register+0x64/0xf0 > Oct 11 14:42:08 xanatos kernel: [18165.847767] [<ffffffffa003ec34>] usb_register_driver+0xc4/0x180 [usbcore] > Oct 11 14:42:08 xanatos kernel: [18165.847770] [<ffffffffa01f0000>] ? 0xffffffffa01effff > Oct 11 14:42:08 xanatos kernel: [18165.847773] [<ffffffffa01f001e>] uas_driver_init+0x1e/0x20 [uas] > Oct 11 14:42:08 xanatos kernel: [18165.847775] [<ffffffff8100210a>] do_one_initcall+0xda/0x180 > Oct 11 14:42:08 xanatos kernel: [18165.847778] [<ffffffff81080313>] ? __blocking_notifier_call_chain+0x63/0x80 > Oct 11 14:42:08 xanatos kernel: [18165.847782] [<ffffffff810c7e42>] load_module+0x14b2/0x1ad0 > Oct 11 14:42:08 xanatos kernel: [18165.847784] [<ffffffff810c4680>] ? show_initstate+0x50/0x50 > Oct 11 14:42:08 xanatos kernel: [18165.847788] [<ffffffff810c8532>] SyS_init_module+0xd2/0x120 > Oct 11 14:42:08 xanatos kernel: [18165.847791] [<ffffffff816183a9>] system_call_fastpath+0x16/0x1b > > This looks possibly related to commit > 5e4c0d974139a98741b829b27cf38dc8f9284490 "lib/radix-tree.c: make > radix_tree_node_alloc() work correctly within interrupt". I'll revert > the commit, and see if the warning disappears. In the meantime, can you > look into fixing this? > > Thanks, > Sarah Sharp -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
