On Tue, Jul 5, 2016 at 5:42 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 5 Jul 2016, Dmitry Vyukov wrote: > >> Hello, >> >> The following program trigger the following WARNING: >> >> ------------[ cut here ]------------ >> WARNING: CPU: 0 PID: 6263 at mm/page_alloc.c:3584[< inline >] >> __alloc_pages_slowpath mm/page_alloc.c:3584 >> WARNING: CPU: 0 PID: 6263 at mm/page_alloc.c:3584[< none >] >> __alloc_pages_nodemask+0x1731/0x2350 mm/page_alloc.c:3854 >> Modules linked in: >> CPU: 0 PID: 6263 Comm: a.out Not tainted 4.7.0-rc5+ #28 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> ffffffff880b58e0 ffff88006ad3f778 ffffffff82cc01af ffffffff86cf92c0 >> fffffbfff1016b1c 0000000000000000 0000000000000000 ffffffff86cf92c0 >> ffffffff816b7881 0000000000000009 ffff88006ad3f7c0 ffffffff8136d17f >> Call Trace: >> [< inline >] __dump_stack lib/dump_stack.c:15 >> [<ffffffff82cc01af>] dump_stack+0x12e/0x18f lib/dump_stack.c:51 >> [<ffffffff8136d17f>] __warn+0x19f/0x1e0 kernel/panic.c:516 >> [<ffffffff8136d38c>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:551 >> [< inline >] __alloc_pages_slowpath mm/page_alloc.c:3584 >> [<ffffffff816b7881>] __alloc_pages_nodemask+0x1731/0x2350 mm/page_alloc.c:3854 >> [< inline >] __alloc_pages include/linux/gfp.h:432 >> [< inline >] __alloc_pages_node include/linux/gfp.h:445 >> [< inline >] alloc_pages_node include/linux/gfp.h:459 >> [<ffffffff8120b28f>] dma_generic_alloc_coherent+0xff/0x250 >> arch/x86/kernel/pci-dma.c:102 >> [< inline >] dma_alloc_attrs include/linux/dma-mapping.h:374 >> [< inline >] dma_alloc_coherent include/linux/dma-mapping.h:401 >> [<ffffffff84699f1d>] hcd_buffer_alloc+0x1dd/0x400 drivers/usb/core/buffer.c:140 >> [<ffffffff8465a670>] usb_alloc_coherent+0x60/0x80 drivers/usb/core/usb.c:740 >> [<ffffffff846a12ba>] usbdev_mmap+0x19a/0x650 drivers/usb/core/devio.c:244 >> [<ffffffff8175ae2f>] mmap_region+0x87f/0xfe0 mm/mmap.c:1507 >> [<ffffffff8175bf2d>] do_mmap+0x99d/0xbf0 mm/mmap.c:1286 >> [< inline >] do_mmap_pgoff include/linux/mm.h:2005 >> [<ffffffff81701e66>] vm_mmap_pgoff+0x156/0x1a0 mm/util.c:302 >> [< inline >] SYSC_mmap_pgoff mm/mmap.c:1336 >> [<ffffffff81754dea>] SyS_mmap_pgoff+0x34a/0x580 mm/mmap.c:1294 >> [< inline >] SYSC_mmap arch/x86/kernel/sys_x86_64.c:95 >> [<ffffffff81208ff6>] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:86 >> [<ffffffff86a94e00>] entry_SYSCALL_64_fastpath+0x23/0xc1 >> arch/x86/entry/entry_64.S:207 >> ---[ end trace 94402e12bc6578e5 ]--- >> >> // autogenerated by syzkaller (http://github.com/google/syzkaller) >> #include <pthread.h> >> #include <stdint.h> >> #include <string.h> >> #include <sys/syscall.h> >> #include <unistd.h> >> #include <sys/mman.h> >> >> int main() >> { >> int fd = open("/dev/bus/usb/001/001", 0x800ul, 0); >> mmap((void*)0x201c4000ul, 0xc00000ul, 0x3ul, 0x20012ul, fd, 0x0ul); >> return 0; >> } >> >> On commit 1a0a02d1efa066001fd315c1b4df583d939fa2c4 (Jun 30). > > This is an attempt to allocate 12 MB of coherent memory. As far as I > can tell, the WARNING refers to invalid bits set in the gfp_mask. > > However the original allocation comes from usbdev_mmap() in > drivers/usb/core/devio.c: > > mem = usb_alloc_coherent(ps->dev, size, GFP_USER, &dma_handle); > > I don't see how that ends up causing the WARNING. There is also arch_dma_alloc_attrs on the way: 132 bool arch_dma_alloc_attrs(struct device **dev, gfp_t *gfp) 133 { 134 if (!*dev) 135 *dev = &x86_dma_fallback_dev; 136 137 *gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32); 138 *gfp = dma_alloc_coherent_gfp_flags(*dev, *gfp); 139 140 if (!is_device_dma_capable(*dev)) 141 return false; 142 return true; 143 144 } 145 EXPORT_SYMBOL(arch_dma_alloc_attrs); -- 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
