Re: [LTP] MAP_LOCKED issue in mmap with MAP_ANYNOMOUS

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Satish Gedela" <satish.gedela@lge.com>
> To: "Jan Stancek" <jstancek@redhat.com>
> Cc: ltp-list@lists.sourceforge.net
> Sent: Friday, 20 March, 2015 12:42:00 PM
> Subject: RE: [LTP] MAP_LOCKED issue in mmap with MAP_ANYNOMOUS
> 
> 
> 
> > -----Original Message-----
> > From: Jan Stancek [mailto:jstancek@redhat.com]
> > Sent: Friday, March 20, 2015 1:41 PM
> > To: Satish Gedela/LGSIA CSP-2(satish.gedela@lge.com)
> > Cc: ltp-list@lists.sourceforge.net
> > Subject: Re: [LTP] MAP_LOCKED issue in mmap with MAP_ANYNOMOUS
> > 
> > 
> > 
> > ----- Original Message -----
> > > From: "Satish Gedela" <satish.gedela@lge.com>
> > > To: ltp-list@lists.sourceforge.net
> > > Sent: Friday, 20 March, 2015 6:28:34 AM
> > > Subject: [LTP] MAP_LOCKED issue in mmap with MAP_ANYNOMOUS
> > >
> > > Dear all,
> > >
> > > I am newbie to open source, forgive me with text format I am trying to
> > > run  LTP with kernel 3.16 on target board having cortex A9 processor ,
> > > Facing issue with below test case:
> > > Test script  name: "memcg_function_test.sh"
> > > Test case description:  "Test mmap(locked) + alloc_mem > limit_in_bytes"
> > >
> > > Analysis:  memcg_function_test.sh   -----> test_proc_kill
> > > 						                  ------->memcg_lib.sh
> > >
> > -------->memcg_process
> > >     memcg_process
> > >
> > > ------>ltp/testcases/kernel/controllers/memcg/functional/memcg_process
> > > .c
> > >
> > > mmap_lock1 () function is calling in memcg_process.c and it calls mmap
> > > function with flags MAP_PRIVATE | MAP_ANYNOMOUS | MAP_LOCKED
> > > {noformat} p = mmap(NULL, memsize, PROT_WRITE | PROT_READ,
> > >       MAP_PRIVATE | MAP_LOCKED, 0, 0); {noformat}
> > >
> > > but man page of mmap is mentioned as:
> > > {noformat}
> > > MAP_ANONYMOUS
> > >         The  mapping  is  not  backed  by  any  file; its contents are
> > >         initialized to zero.  The fd and offset arguments are
> > >         ignored; however, some implementations require fd to be -1 if
> > >         MAP_ANONYMOUS (or MAP_ANON) is specified, and portable
> > >         applications should ensure this.  The use of MAP_ANONYMOUS in
> > >         conjunction with MAP_SHARED is only supported on Linux
> > >         since kernel 2.4.
> > > {noformat}
> > >
> > > In my case, we are trying to lock the pages with flags  MAP_PRIVATE |
> > > MAP_ANYNOMOUS |  MAP_LOCKED  and  it is failing.
> > 
> > Hi,
> > 
> > failing how? EINVAL or something else?
> > Do you see mmap14 failing as well? If so, can you run it via strace?
> > 
> > Regards,
> > Jan
> > 
> Hi Jan,
> Failing  to kill process PID.

It seems that MAP_LOCKED can now silently fail.

https://lkml.org/lkml/2015/1/19/28
http://marc.info/?l=linux-mm&m=142122902313315&w=2

Those posts contain also kernel commit IDs that are likely responsible
for same problem you see.

Regards,
Jan

> Not getting EINVAL
> I did not test mmap14 but I replaced 5th argument with  '-1' instead of '0'
> (Based on mmap14 test case)
> still getting test case failure.
> 
> Test procedure followed:
> 
> Test case description : "kill the process if memory limit exceeds ,
> Process memory locked through MAP_LOCKED  in test_ case_ 14 and using mlock()
> in test_case_ 15"
> 
> Running LTP on work station using
> 	$make configure
> 	$make
> 	$make install
> And copy ltp , kernel, sysinfo.sh, tools  into target directory " /opt "
> and on target running below commnad
> 
> #./runltp -f controllers  > log.txt
> 
> From log report, identified mmap-lock1 (MAP_LOCKED)  is failing and
> mmap-lock2 (mlock2)  is passing
> So from the memcg_process.c file
> 	mmap_lock1() is using mmap () with MAP_PRIVATE | MAP_ANYNOMOUS | MAP_LOCKED
> 	mmap_lock2 is using mmap () with MAP_PRIVATE | MAP_ANYNOMOUS
> 	and mlock() function call.
> 
>  In process of debugging, I replaced mmap_lock1 with mmap_lock2 , in test
>  _case_ 14 and it is working successfully.
> So I identified issue is in mmap() call and
> replaced flag as "MAP_SHARED | MAP_LOCKED"  and  "MAP_PRIVATE  | MAP_LOCKED
> "in mmap,
> it is working successfully in both cases but not with MAP_ANYNOMOUS flag.
> 
> Regards
> Satish.G
> 
> > > and with  MAP_SHARED | MAP_ANYNOMOUS |  MAP_LOCKED , it is failing
> > but
> > > with MAP_PRIVATE | MAP_LOCKED and with MAP_SHARED |
> > MAP_LOCKED it is
> > > working.
> > >
> > > Is there any changes made to kernel or test case has to update with
> > > MAP_SHARED instead of MAP_PRIVATE flag.
> > >
> > > Thank you in advance.
> > > Regards
> > > Satish.G
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > 
> > 
> > 
> > >
> > >
> > >
> > >
> > >
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