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

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Message-ID: <YpZTS5R+3cisLCzl@qian>
Date:   Tue, 31 May 2022 13:41:31 -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 06:01:58PM +0100, Will Deacon wrote:
> Have you spotted any pattern for when the leak occurs? How are you
> terminating the guest?

It just to send a SIGTERM to the qemu-system-aarch64 process. Origially,
right after sending the signal, it will remove_id/unbind from the vfio-pci
and then bind to the original (ixgbe) driver. However, since the process
might take a while to clean off itself, the bind might failed with -EBUSY.
I could reproduce it a few times one day while was unable to do so some
other days.

Later, we changed the code to make sure the process is disappeard first and
then remove_id/bind/unbind. Apparently, it make harder to reproduce if not
totally eliminate it.