From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dmitry Safonov <0x7f454c46@gmail.com>
Subject: Re: [PATCHv4 17/28] x86/vdso: Switch image on
 setns()/unshare()/clone()
Date: Sun, 16 Jun 2019 18:51:12 +0100
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References: <20190612192628.23797-1-dima@arista.com>
 <20190612192628.23797-18-dima@arista.com>
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To: Thomas Gleixner <tglx@linutronix.de>, Dmitry Safonov <dima@arista.com>
Cc: linux-kernel@vger.kernel.org, Adrian Reber <adrian@lisas.de>, Andrei Vagin <avagin@openvz.org>, Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>, Christian Brauner <christian.brauner@ubuntu.com>, Cyrill Gorcunov <gorcunov@openvz.org>, "Eric W. Biederman" <ebiederm@xmission.com>, "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>, Jann Horn <jannh@google.com>, Jeff Dike <jdike@addtoit.com>, Oleg Nesterov <oleg@redhat.com>, Pavel Emelyanov <xemul@virtuozzo.com>, Shuah Khan <shuah@kernel.org>, Vincenzo Frascino <vincenzo.frascino@arm.com>, containers@lists.linux-foundation.org, criu@openvz.org, linux-api@vger.kernel.org, x86@kernel.org, Andrei Vagin <avagin@gmail.com>
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On 6/14/19 3:05 PM, Thomas Gleixner wrote:
> On Wed, 12 Jun 2019, Dmitry Safonov wrote:
>>  
>> +#ifdef CONFIG_TIME_NS
>> +int vdso_join_timens(struct task_struct *task)
>> +{
>> +	struct mm_struct *mm = task->mm;
>> +	struct vm_area_struct *vma;
>> +
>> +	if (down_write_killable(&mm->mmap_sem))
>> +		return -EINTR;
>> +
>> +	for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> +		unsigned long size = vma->vm_end - vma->vm_start;
>> +
>> +		if (vma_is_special_mapping(vma, &vvar_mapping) ||
>> +		    vma_is_special_mapping(vma, &vdso_mapping))
>> +			zap_page_range(vma, vma->vm_start, size);
>> +	}
>> +
>> +	up_write(&mm->mmap_sem);
>> +	return 0;
>> +}
>> +#else /* CONFIG_TIME_NS */
>> +int vdso_join_timens(struct task_struct *task)
>> +{
>> +	return -ENXIO;
>> +}
> 
> Is that else path really required? The callsite is only compiled when
> CONFIG_TIME_NS is enabled, right?

Oh, yes - will drop this.

Thanks,
          Dmitry