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Subject: Re: [PATCH v2 7/9] trace_uprobe/sdt: Fix multiple update of same
 reference counter
To:     Oleg Nesterov <oleg@redhat.com>
Cc:     mhiramat@kernel.org, peterz@infradead.org,
        srikar@linux.vnet.ibm.com, rostedt@goodmis.org, acme@kernel.org,
        ananth@linux.vnet.ibm.com, akpm@linux-foundation.org,
        alexander.shishkin@linux.intel.com, alexis.berlemont@gmail.com,
        corbet@lwn.net, dan.j.williams@intel.com, jolsa@redhat.com,
        kan.liang@intel.com, kjlx@templeofstupid.com,
        kstewart@linuxfoundation.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org,
        naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, tglx@linutronix.de,
        yao.jin@linux.intel.com, fengguang.wu@intel.com,
        jglisse@redhat.com,
        Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
References: <20180404083110.18647-1-ravi.bangoria@linux.vnet.ibm.com>
 <20180404083110.18647-8-ravi.bangoria@linux.vnet.ibm.com>
 <20180409131730.GA25631@redhat.com>
From:   Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Date:   Mon, 9 Apr 2018 19:02:02 +0530
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Hi Oleg,

On 04/09/2018 06:47 PM, Oleg Nesterov wrote:
> On 04/04, Ravi Bangoria wrote:
>> +static void sdt_add_mm_list(struct trace_uprobe *tu, struct mm_struct *mm)
>> +{
>> +	struct mmu_notifier *mn;
>> +	struct sdt_mm_list *sml = kzalloc(sizeof(*sml), GFP_KERNEL);
>> +
>> +	if (!sml)
>> +		return;
>> +	sml->mm = mm;
>> +	list_add(&(sml->list), &(tu->sml.list));
>> +
>> +	/* Register mmu_notifier for this mm. */
>> +	mn = kzalloc(sizeof(*mn), GFP_KERNEL);
>> +	if (!mn)
>> +		return;
>> +
>> +	mn->ops = &sdt_mmu_notifier_ops;
>> +	__mmu_notifier_register(mn, mm);
>> +}
> I didn't read this version yet, just one question...
>
> So now it depends on CONFIG_MMU_NOTIFIER, yes? I do not see any changes in Kconfig
> files, this doesn't look right...

Yes, you are write. I'll make CONFIG_UPROBE_EVENTS dependent on
CONFIG_MMU_NOTIFIER.

Thanks,
Ravi