Re: [PATCH] x86/vdso: add mremap hook to vm_special_mapping

From: kbuild test robot <lkp@intel.com>
To: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: kbuild-all@01.org, linux-kernel@vger.kernel.org,
	luto@amacapital.net, tglx@linutronix.de, mingo@redhat.com,
	hpa@zytor.com, x86@kernel.org, akpm@linux-foundation.org,
	linux-mm@kvack.org, 0x7f454c46@gmail.com,
	Dmitry Safonov <dsafonov@virtuozzo.com>
Subject: Re: [PATCH] x86/vdso: add mremap hook to vm_special_mapping
Date: Mon, 11 Apr 2016 23:41:54 +0800	[thread overview]
Message-ID: <201604112306.pt7CJqPB%fengguang.wu@intel.com> (raw)
In-Reply-To: <1460388169-13340-1-git-send-email-dsafonov@virtuozzo.com>

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Hi Dmitry,

[auto build test WARNING on v4.6-rc3]
[also build test WARNING on next-20160411]
[cannot apply to tip/x86/vdso luto/next]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/x86-vdso-add-mremap-hook-to-vm_special_mapping/20160411-232653
config: x86_64-randconfig-x000-201615 (attached as .config)
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   arch/x86/entry/vdso/vma.c: In function 'vdso_mremap':
>> arch/x86/entry/vdso/vma.c:105:18: warning: unused variable 'regs' [-Wunused-variable]
     struct pt_regs *regs = current_pt_regs();
                     ^

vim +/regs +105 arch/x86/entry/vdso/vma.c

    89	static int vdso_fault(const struct vm_special_mapping *sm,
    90			      struct vm_area_struct *vma, struct vm_fault *vmf)
    91	{
    92		const struct vdso_image *image = vma->vm_mm->context.vdso_image;
    93	
    94		if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
    95			return VM_FAULT_SIGBUS;
    96	
    97		vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
    98		get_page(vmf->page);
    99		return 0;
   100	}
   101	
   102	static int vdso_mremap(const struct vm_special_mapping *sm,
   103			      struct vm_area_struct *new_vma)
   104	{
 > 105		struct pt_regs *regs = current_pt_regs();
   106	
   107	#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
   108		/* Fixing userspace landing - look at do_fast_syscall_32 */
   109		if (regs->ip == (unsigned long)current->mm->context.vdso +
   110				vdso_image_32.sym_int80_landing_pad
   111	#ifdef CONFIG_IA32_EMULATION
   112			&& current_thread_info()->status & TS_COMPAT
   113	#endif

---
0-DAY kernel test infrastructure                Open Source Technology Center
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