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Subject: Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference
 count (semaphore)
To:     Oleg Nesterov <oleg@redhat.com>
Cc:     mhiramat@kernel.org, peterz@infradead.org,
        srikar@linux.vnet.ibm.com, acme@kernel.org,
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        tmricht@linux.vnet.ibm.com, willy@infradead.org,
        yao.jin@linux.intel.com, fengguang.wu@intel.com,
        Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com>
 <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com>
 <20180314165943.GA5948@redhat.com>
From:   Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Date:   Mon, 19 Mar 2018 09:58:28 +0530
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Hi Oleg,

On 03/14/2018 10:29 PM, Oleg Nesterov wrote:
> On 03/13, Ravi Bangoria wrote:
>> +static bool sdt_valid_vma(struct trace_uprobe *tu, struct vm_area_struct *vma)
>> +{
>> +	unsigned long vaddr = vma_offset_to_vaddr(vma, tu->ref_ctr_offset);
>> +
>> +	return tu->ref_ctr_offset &&
>> +		vma->vm_file &&
>> +		file_inode(vma->vm_file) == tu->inode &&
>> +		vma->vm_flags & VM_WRITE &&
>> +		vma->vm_start <= vaddr &&
>> +		vma->vm_end > vaddr;
>> +}
> Perhaps in this case a simple
>
> 		ref_ctr_offset < vma->vm_end - vma->vm_start
>
> check without vma_offset_to_vaddr() makes more sense, but I won't insist.
>

I still don't get this. This seems a comparison between file offset and size
of the vma. Shouldn't we need to consider pg_off here?

Thanks,
Ravi