Re: [LTP] [patch] swapon03 cleanup v2

[Rishikesh K Rajak <risrajak@linux.vnet.ibm.com>]

Hi Murlin,

Can you please look into this problem again ? It seems you had some discussion
with garret to reach to some conclusion about the reported failure.

-Rishi

On Sat, Mar 13, 2010 at 01:56:25PM -0800, Garrett Cooper wrote:
> On Sat, Mar 13, 2010 at 9:26 AM, Murlin Wenzel <mwenzel@novell.com> wrote:
> >>>> On 3/13/2010 at 12:32 AM, in message
> > <364299f41003122332u3c4f93a7td3c1f9db1a360bec@mail.gmail.com>, Garrett Cooper
> > <yanegomi@gmail.com> wrote:
> >> On Thu, Mar 11, 2010 at 7:48 AM, Murlin Wenzel <mwenzel@novell.com> wrote:
> >>>>>> On 3/10/2010 at 05:15 AM, in message
> >>> <20100310121544.GB11404@linux.vnet.ibm.com>, Rishikesh K Rajak
> >>> <risrajak@linux.vnet.ibm.com> wrote:
> >>>> On Thu, Feb 25, 2010 at 11:56:15AM +0530, Rishikesh K Rajak wrote:
> >>>>> On Wed, Feb 24, 2010 at 05:08:56PM -0800, Garrett Cooper wrote:
> >>>>> > On Wed, Feb 24, 2010 at 3:49 PM, Murlin Wenzel <mwenzel@novell.com> wrote:
> >>>>> > > Added clean_swap() to cleanup routine.  This makes sure all leftover swap
> >>>> files are removed.
> >>>>> > >
> >>>>> > > Signed-off-By:  Murlin Ray Wenzel mwenzel@novell.com
> >>>>> >
> >>>>> > Committed -- thanks!
> >>>>> > -Garrett
> >>>>>
> >>>>> Thanks Garret & Murlin.
> >>>>
> >>>>
> >>>> Hi Murlin,
> >>>>
> >>>> can you please look into this failure as it still fails on my SLES11 &
> >>>> RHEl5.4
> >>>> boxes.
> >>>>
> >>>> [root@mx3455a bin]# ./swapon03
> >>>> swapon03    1  TFAIL  :  Failed swapon for file swapfile29: errno=EPERM(1):
> >>>> Operation not permitted
> >>>> swapon03    0  TWARN  :  tst_rmdir(): rmobj(/tmp/swasf2sLb) failed:
> >>>> unlink(/tmp/swasf2sLb/swapfile22) failed; errno=1: Operation not permitted
> >>>> swapon03    1  TFAIL  :  Failed to setup swaps
> >>>>
> >>>> attached is the strace log.
> >>>
> >>> That's the other part of the problem that I'm not sure what to do with yet.
> >> The original test was written entirely based on the assumption that there
> >> were always a max of 30 swap files available.  With newer kernels (SLE11
> >> RHEL5.4) the kernel can be configured so that the max could be as low as 29
> >> if not 28.  The kernel is doing the right thing returning EPERM, but the test
> >> needs to be re-worked to deal with new maximum limits/possibilites.
> >>
> >> It should actually be KERNEL_MAX - (CONFIG_MIGRATION enabled ? 2 : 0)
> >> - used_swap_devices ...
> >>
> >> NOTES
> >>        The partition or path must be prepared with mkswap(8).
> >>
> >>        There is an upper limit on the number of swap files that may  be
> >> used,
> >>        defined  by  the  kernel constant MAX_SWAPFILES.  Before kernel
> >> 2.4.10,
> >>        MAX_SWAPFILES has the value 8; since kernel 2.4.10, it  has  the
> >> value
> >>        32.  Since kernel 2.6.18, the limit is decreased by 2 (thus: 30) if
> >> the
> >>        kernel is built with the CONFIG_MIGRATION option  (which  reserves
> >> two
> >>        swap  table  entries  for  the  page migration features of mbind(2)
> >> and
> >>        migrate_pages(2)).
> >>
> >>     The fun unknown is CONFIG_MIGRATION -- how do you know whether or
> >> not this is set from userspace? There's too much handwaving in this
> >> testcase that needs to be fixed.
> >
> > That's my point.  There are even more config options in newer kernels which affect the number of swap files.  AFAIK none of that info is available to userspace app.  The only known is MAX_SWAPFILES which is 32, or 8 on 2.4 kernels.  The current test makes an assumption that there would always be 32 or 30 swapfiles available based on a kernel config at some point in the past.  I'm thinking the test should just use MAX_SWAPFILES(32 in this case), try to create that many until EPERM error is returned, provide that TINFO to tester, clean up everything and if that succeeds call the test a pass.  It is too ugly trying to start guessing about is 29 ok, or 30 ok or 32 ok with no way of knowing how the kernel was configured.
> 
>     Here's a good question: where is this information stored in the
> kernel? If we can create an ltp test module to export some of this
> data [and extend it to other reporting as necessary] via sysfs
> STRICTLY for testing, it would help determinism a lot.
> Thanks,
> -Garrett

-- 
Thanks & Regards
Rishi
LTP Maintainer
IBM, LTC, Bangalore
Please join IRC #ltp @ irc.freenode.net

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