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Message-ID: <20210818131117.x7omzb2wkjq7le3s@example.org>
Date: Wed, 18 Aug 2021 15:11:17 +0200
From: Alexey Gladkov <legion@...nel.org>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: "Ma, XinjianX" <xinjianx.ma@...el.com>,
"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
lkp <lkp@...el.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"axboe@...nel.dk" <axboe@...nel.dk>,
"christian.brauner@...ntu.com" <christian.brauner@...ntu.com>,
"containers@...ts.linux-foundation.org" <containers@...ts.linux-foundation.org>,
"jannh@...gle.com" <jannh@...gle.com>,
"keescook@...omium.org" <keescook@...omium.org>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"oleg@...hat.com" <oleg@...hat.com>,
"torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v11 5/9] Reimplement RLIMIT_MSGQUEUE on top of ucounts
On Tue, Aug 17, 2021 at 10:47:14AM -0500, Eric W. Biederman wrote:
> "Ma, XinjianX" <xinjianx.ma@...el.com> writes:
>
> > Hi Alexey,
> >
> > When lkp team run kernel selftests, we found after these series of patches, testcase mqueue: mq_perf_tests
> > in kselftest failed with following message.
>
> Which kernel was this run against?
>
> Where can the mq_perf_tests that you ran and had problems with be found?
>
> During your run were you using user namespaces as part of your test
> environment?
>
> The error message too many files corresponds to the error code EMFILES
> which is the error code that is returned when the rlimit is reached.
>
> One possibility is that your test environment was run in a user
> namespace and so you wound up limited by rlimit of the user who created
> the user namespace at the point of user namespace creation.
>
> At this point if you can give us enough information to look into this
> and attempt to reproduce it that would be appreciated.
I was able to reproduce it on master without using user namespace.
I suspect that the maximum value is not assigned here [1]:
set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, task_rlimit(&init_task, RLIMIT_MSGQUEUE));
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/fork.c#n832
> > If you confirm and fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot lkp@...el.com
> >
> > ```
> > # selftests: mqueue: mq_perf_tests
> > #
> > # Initial system state:
> > # Using queue path: /mq_perf_tests
> > # RLIMIT_MSGQUEUE(soft): 819200
> > # RLIMIT_MSGQUEUE(hard): 819200
> > # Maximum Message Size: 8192
> > # Maximum Queue Size: 10
> > # Nice value: 0
> > #
> > # Adjusted system state for testing:
> > # RLIMIT_MSGQUEUE(soft): (unlimited)
> > # RLIMIT_MSGQUEUE(hard): (unlimited)
> > # Maximum Message Size: 16777216
> > # Maximum Queue Size: 65530
> > # Nice value: -20
> > # Continuous mode: (disabled)
> > # CPUs to pin: 3
> > # ./mq_perf_tests: mq_open() at 296: Too many open files
> > not ok 2 selftests: mqueue: mq_perf_tests # exit=1
> > ```
> >
> > Test env:
> > rootfs: debian-10
> > gcc version: 9
> >
> > ------
> > Thanks
> > Ma Xinjian
>
> Eric
>
--
Rgrds, legion
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