linux-kernel - Re: [PATCH] iommu/ipmmu-vmsa: Fix allocation in atomic context

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Message-ID: <20180727074152.bmso3y4lr53ixo2f@8bytes.org>
Date:   Fri, 27 Jul 2018 09:41:52 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Magnus Damm <magnus.damm@...il.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        iommu@...ts.linux-foundation.org,
        linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/ipmmu-vmsa: Fix allocation in atomic context

On Fri, Jul 20, 2018 at 06:16:59PM +0200, Geert Uytterhoeven wrote:
> When attaching a device to an IOMMU group with
> CONFIG_DEBUG_ATOMIC_SLEEP=y:
> 
>     BUG: sleeping function called from invalid context at mm/slab.h:421
>     in_atomic(): 1, irqs_disabled(): 128, pid: 61, name: kworker/1:1
>     ...
>     Call trace:
>      ...
>      arm_lpae_alloc_pgtable+0x114/0x184
>      arm_64_lpae_alloc_pgtable_s1+0x2c/0x128
>      arm_32_lpae_alloc_pgtable_s1+0x40/0x6c
>      alloc_io_pgtable_ops+0x60/0x88
>      ipmmu_attach_device+0x140/0x334
> 
> ipmmu_attach_device() takes a spinlock, while arm_lpae_alloc_pgtable()
> allocates memory using GFP_KERNEL.  Originally, the ipmmu-vmsa driver
> had its own custom page table allocation implementation using
> GFP_ATOMIC, hence the spinlock was fine.
> 
> Fix this by replacing the spinlock by a mutex, like the arm-smmu driver
> does.
> 
> Fixes: f20ed39f53145e45 ("iommu/ipmmu-vmsa: Use the ARM LPAE page table allocator")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
>  drivers/iommu/ipmmu-vmsa.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)

Applied, thanks.