Date: Thu, 19 Aug 2021 19:26:18 +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 Thu, Aug 19, 2021 at 10:10:26AM -0500, Eric W. Biederman wrote: > Alexey Gladkov <legion@...nel.org> writes: > > > 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 : > > > > set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, task_rlimit(&init_task, RLIMIT_MSGQUEUE)); > > > >  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/fork.c#n832 > > The rlimits for init_task are set to INIT_RLIMITS. > In INIT_RLIMITS RLIMIT_MSGQUEUE is set to MQ_MAX_BYTES > > So that definitely means that as the code is current constructed the > rlimit can not be effectively raised. > > So it looks like we are just silly and preventing the initial rlimits > from being raised. > > So we probably want to do something like: Damn, you are faster than me! :) > diff --git a/kernel/fork.c b/kernel/fork.c > index bc94b2cc5995..557ce0083ba3 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -825,13 +825,13 @@ void __init fork_init(void) > init_task.signal->rlim[RLIMIT_SIGPENDING] = > init_task.signal->rlim[RLIMIT_NPROC]; > > + /* For non-rlimit ucounts make their default limit max_threads/2 */ > for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++) > init_user_ns.ucount_max[i] = max_threads/2; > > - set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, task_rlimit(&init_task, RLIMIT_NPROC)); > - set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, task_rlimit(&init_task, RLIMIT_MSGQUEUE)); > - set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, task_rlimit(&init_task, RLIMIT_SIGPENDING)); > - set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, task_rlimit(&init_task, RLIMIT_MEMLOCK)); > + /* In init_user_ns default rlimit to be the only limit */ > + for (; i < UCOUNT_COUNTS; i++) > + set_rlimit_ucount_max(&init_user_ns, i, RLIMIT_INFINITY); s/RLIMIT_INFINITY/RLIM_INFINITY/ > > #ifdef CONFIG_VMAP_STACK > cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache", > Acked-by: Alexey Gladkov <legion@...nel.org> I cannot complete this test on my laptop. On 4Gb, the test ends with oom-killer. But with this patch, the test definitely passes the moment of the previous fall. -- Rgrds, legion
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