From: Daniel Jordan <daniel.m.jordan@oracle.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>,
akpm@linux-foundation.org, dave@stgolabs.net, jack@suse.cz,
cl@linux.com, linux-mm@kvack.org, kvm@vger.kernel.org,
kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org,
alex.williamson@redhat.com, paulus@ozlabs.org,
benh@kernel.crashing.org, mpe@ellerman.id.au, hao.wu@intel.com,
atull@kernel.org, mdf@kernel.org, aik@ozlabs.ru
Subject: Re: [PATCH 1/5] vfio/type1: use pinned_vm instead of locked_vm to account pinned pages
Date: Mon, 11 Feb 2019 18:11:53 -0500 [thread overview]
Message-ID: <20190211231152.qflff6g2asmkb6hr@ca-dmjordan1.us.oracle.com> (raw)
In-Reply-To: <20190211225620.GO24692@ziepe.ca>
On Mon, Feb 11, 2019 at 03:56:20PM -0700, Jason Gunthorpe wrote:
> On Mon, Feb 11, 2019 at 05:44:33PM -0500, Daniel Jordan wrote:
> > @@ -266,24 +267,15 @@ static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
> > if (!mm)
> > return -ESRCH; /* process exited */
> >
> > - ret = down_write_killable(&mm->mmap_sem);
> > - if (!ret) {
> > - if (npage > 0) {
> > - if (!dma->lock_cap) {
> > - unsigned long limit;
> > -
> > - limit = task_rlimit(dma->task,
> > - RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> > + pinned_vm = atomic64_add_return(npage, &mm->pinned_vm);
> >
> > - if (mm->locked_vm + npage > limit)
> > - ret = -ENOMEM;
> > - }
> > + if (npage > 0 && !dma->lock_cap) {
> > + unsigned long limit = task_rlimit(dma->task, RLIMIT_MEMLOCK) >>
> > +
> > - PAGE_SHIFT;
>
> I haven't looked at this super closely, but how does this stuff work?
>
> do_mlock doesn't touch pinned_vm, and this doesn't touch locked_vm...
>
> Shouldn't all this be 'if (locked_vm + pinned_vm < RLIMIT_MEMLOCK)' ?
>
> Otherwise MEMLOCK is really doubled..
So this has been a problem for some time, but it's not as easy as adding them
together, see [1][2] for a start.
The locked_vm/pinned_vm issue definitely needs fixing, but all this series is
trying to do is account to the right counter.
Daniel
[1] http://lkml.kernel.org/r/20130523104154.GA23650@twins.programming.kicks-ass.net
[2] http://lkml.kernel.org/r/20130524140114.GK23650@twins.programming.kicks-ass.net
next prev parent reply other threads:[~2019-02-11 23:11 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-11 22:44 [PATCH 0/5] use pinned_vm instead of locked_vm to account pinned pages Daniel Jordan
2019-02-11 22:44 ` [PATCH 1/5] vfio/type1: " Daniel Jordan
2019-02-11 22:56 ` Jason Gunthorpe
2019-02-11 23:11 ` Daniel Jordan [this message]
2019-02-12 18:41 ` Alex Williamson
2019-02-13 0:26 ` Daniel Jordan
2019-02-13 20:03 ` Alex Williamson
2019-02-13 23:07 ` Jason Gunthorpe
2019-02-14 1:46 ` Daniel Jordan
2019-02-11 22:44 ` [PATCH 2/5] vfio/spapr_tce: " Daniel Jordan
2019-02-12 6:56 ` Alexey Kardashevskiy
2019-02-12 16:50 ` Christopher Lameter
2019-02-12 17:18 ` Daniel Jordan
2019-02-13 0:37 ` Alexey Kardashevskiy
2019-02-12 18:56 ` Alex Williamson
2019-02-13 0:34 ` Alexey Kardashevskiy
2019-02-11 22:44 ` [PATCH 3/5] fpga/dlf/afu: " Daniel Jordan
2019-02-11 22:44 ` [PATCH 4/5] powerpc/mmu: " Daniel Jordan
2019-02-13 1:14 ` kbuild test robot
2019-02-11 22:44 ` [PATCH 5/5] kvm/book3s: " Daniel Jordan
2019-02-13 1:43 ` kbuild test robot
2019-02-11 22:54 ` [PATCH 0/5] " Jason Gunthorpe
2019-02-11 23:15 ` Daniel Jordan
2019-02-14 1:53 ` Ira Weiny
2019-02-14 6:00 ` Jason Gunthorpe
2019-02-14 19:33 ` Ira Weiny
2019-02-14 20:12 ` Jason Gunthorpe
2019-02-14 21:46 ` Ira Weiny
2019-02-14 22:16 ` Jason Gunthorpe
2019-02-15 15:26 ` Christopher Lameter
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