From mboxrd@z Thu Jan  1 00:00:00 1970
From: Topi Miettinen <toiwoton@gmail.com>
Subject: Re: [PATCH 09/14] resource limits: track highwater mark of locked
 memory
Date: Fri, 15 Jul 2016 17:39:26 +0000
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To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org, Tony Luck <tony.luck@intel.com>, Fenghua Yu <fenghua.yu@intel.com>, Paolo Bonzini <pbonzini@redhat.com>, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>, Alexander Graf <agraf@suse.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, Doug Ledford <dledford@redhat.com>, Sean Hefty <sean.hefty@intel.com>, Hal Rosenstock <hal.rosenstock@gmail.com>, Mike Marciniszyn <mike.marciniszyn@intel.com>, Dennis Dalessandro <dennis.dalessandro@intel.com>, Christian Benvenuti <benve@cisco.com>, Dave Goodell <dgoodell@cisco.com>, Sudeep Dutt <sudeep.dutt@intel.com>, Ashutosh Dixit <ashutosh.dixit@intel.com>, Alex Williamson <alex.williamson@redhat.com>, Alexei Starovoitov <ast@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, Arnaldo
List-Id: linux-rdma@vger.kernel.org

On 07/15/16 15:14, Oleg Nesterov wrote:
> On 07/15, Topi Miettinen wrote:
>>
>> Track maximum size of locked memory, to be able to configure
>> RLIMIT_MEMLOCK resource limits. The information is available
>> with taskstats and cgroupstats netlink socket.
> 
> So I personally still dislike the very idea of this series... but I won't
> argue if you convince maintainers.
> 
>> @@ -2020,6 +2020,10 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
>>  		return -ENOMEM;
>>  
>>  	update_resource_highwatermark(RLIMIT_STACK, actual_size);
>> +	if (vma->vm_flags & VM_LOCKED)
>> +		update_resource_highwatermark(RLIMIT_MEMLOCK,
>> +					      (mm->locked_vm + grow) <<
>> +					      PAGE_SHIFT);
> 
> Btw this is not right. The same for the previous patch which tracks
> RLIMIT_STACK. The "current" task can debugger/etc.

acct_stack_growth() is called from expand_upwards() and
expand_downwards(). They call security_mmap_addr() and the various LSM
implementations also use current task in the checks. Are these also not
right?

> 
> Yes, yes, this just reminds that the whole rlimit logic in this path
> is broken but still...

I'd be happy to fix the logic with a separate prerequisite patch and
then use the right logic for this patch, but I'm not sure I know how.
Could you elaborate a bit?

-Topi

> 
> Oleg.
> 

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