linux-kernel - Re: [PATCH] KVM: arm64: Fix memory leaks from stage2 pagetable

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Date:   Tue, 31 May 2022 13:23:29 -0400
From:   Qian Cai <quic_qiancai@...cinc.com>
To:     Will Deacon <will@...nel.org>
CC:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kvmarm@...ts.cs.columbia.edu>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] KVM: arm64: Fix memory leaks from stage2 pagetable

On Tue, May 31, 2022 at 05:57:11PM +0100, Will Deacon wrote:
> On Thu, May 26, 2022 at 04:39:56PM -0400, Qian Cai wrote:
> > Running some SR-IOV workloads could trigger some leak reports from
> > kmemleak.
> > 
> > unreferenced object 0xffff080243cef500 (size 128):
> >   comm "qemu-system-aar", pid 179935, jiffies 4298359506 (age 1629.732s)
> >   hex dump (first 32 bytes):
> >     28 00 00 00 01 00 00 00 00 e0 4c 52 03 08 ff ff  (.........LR....
> >     e0 af a4 7f 7c d1 ff ff a8 3c b3 08 00 80 ff ff  ....|....<......
> >   backtrace:
> >      kmem_cache_alloc_trace
> >      kvm_init_stage2_mmu
> 
> Hmm, I can't spot a 128-byte allocation in here so this is pretty cryptic.
> I don't really like the idea of papering over the report; we'd be better off
> trying to reproduce it.

As far as I would like to reproduce, I have tried it in the last a few
weeks without luck. It still happens from time to time though from our
daily CI, so I was thinking to plug the knowns leaks first.