From: Andreas Herrmann <andreas.herrmann-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
To: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: iommu/arm-smmu: Regression (sleeping function called from invalid context)
Date: Fri, 31 Jan 2014 09:46:23 +0100 [thread overview]
Message-ID: <20140131084623.GN13543@alberich> (raw)
In-Reply-To: <20140130235552.GL13543@alberich>
On Fri, Jan 31, 2014 at 12:55:52AM +0100, Andreas Herrmann wrote:
> Hi Will,
>
> Seems that commit a44a9791e778d9ccda50d5534028ed4057a9a45b
> (iommu/arm-smmu: use mutex instead of spinlock for locking page tables)
> introduced a regression.
>
> At least I've hit
>
> BUG: scheduling while atomic: ksoftirqd/0/3/0x00000100
>...
> BUG: sleeping function called from invalid context at mm/page_alloc.c:2679
> in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/0
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.13.0-00016-g6e90346 #413
> [<c0014740>] (unwind_backtrace+0x0/0xf8) from [<c00115b0>] (show_stack+0x10/0x14)
> [<c00115b0>] (show_stack+0x10/0x14) from [<c057ea24>] (dump_stack+0x74/0xa8)
> [<c057ea24>] (dump_stack+0x74/0xa8) from [<c00acc1c>] (__alloc_pages_nodemask+0x174/0x930)
> [<c00acc1c>] (__alloc_pages_nodemask+0x174/0x930) from [<c042a250>] (arm_smmu_handle_mapping+0x470/0x66c)
> [<c042a250>] (arm_smmu_handle_mapping+0x470/0x66c) from [<c0428e74>] (iommu_map+0xf0/0x148)
> [<c0428e74>] (iommu_map+0xf0/0x148) from [<c001935c>] (__map_sg_chunk+0x198/0x2d4)
>...
> Maybe that was the reason why the offending commit was introduced(?).
>
> I think with the current code "atomic allocations" should be used when
> IO page tables are created. With below patch I've not triggered above
> errors.
I think allocating memory with GFP_KERNEL in this dma-mapping path
doesn't seem to be a good idea. What if the DMA operation for which we
modify IO page tables was triggered to free pages (page cache, swap)?
Andreas
WARNING: multiple messages have this Message-ID (diff)
From: andreas.herrmann@calxeda.com (Andreas Herrmann)
To: linux-arm-kernel@lists.infradead.org
Subject: iommu/arm-smmu: Regression (sleeping function called from invalid context)
Date: Fri, 31 Jan 2014 09:46:23 +0100 [thread overview]
Message-ID: <20140131084623.GN13543@alberich> (raw)
In-Reply-To: <20140130235552.GL13543@alberich>
On Fri, Jan 31, 2014 at 12:55:52AM +0100, Andreas Herrmann wrote:
> Hi Will,
>
> Seems that commit a44a9791e778d9ccda50d5534028ed4057a9a45b
> (iommu/arm-smmu: use mutex instead of spinlock for locking page tables)
> introduced a regression.
>
> At least I've hit
>
> BUG: scheduling while atomic: ksoftirqd/0/3/0x00000100
>...
> BUG: sleeping function called from invalid context at mm/page_alloc.c:2679
> in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/0
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.13.0-00016-g6e90346 #413
> [<c0014740>] (unwind_backtrace+0x0/0xf8) from [<c00115b0>] (show_stack+0x10/0x14)
> [<c00115b0>] (show_stack+0x10/0x14) from [<c057ea24>] (dump_stack+0x74/0xa8)
> [<c057ea24>] (dump_stack+0x74/0xa8) from [<c00acc1c>] (__alloc_pages_nodemask+0x174/0x930)
> [<c00acc1c>] (__alloc_pages_nodemask+0x174/0x930) from [<c042a250>] (arm_smmu_handle_mapping+0x470/0x66c)
> [<c042a250>] (arm_smmu_handle_mapping+0x470/0x66c) from [<c0428e74>] (iommu_map+0xf0/0x148)
> [<c0428e74>] (iommu_map+0xf0/0x148) from [<c001935c>] (__map_sg_chunk+0x198/0x2d4)
>...
> Maybe that was the reason why the offending commit was introduced(?).
>
> I think with the current code "atomic allocations" should be used when
> IO page tables are created. With below patch I've not triggered above
> errors.
I think allocating memory with GFP_KERNEL in this dma-mapping path
doesn't seem to be a good idea. What if the DMA operation for which we
modify IO page tables was triggered to free pages (page cache, swap)?
Andreas
next prev parent reply other threads:[~2014-01-31 8:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-30 23:55 iommu/arm-smmu: Regression (sleeping function called from invalid context) Andreas Herrmann
2014-01-30 23:55 ` Andreas Herrmann
2014-01-31 8:46 ` Andreas Herrmann [this message]
2014-01-31 8:46 ` Andreas Herrmann
2014-01-31 9:58 ` Andreas Herrmann
2014-01-31 9:58 ` Andreas Herrmann
2014-02-03 16:31 ` Will Deacon
2014-02-03 16:31 ` Will Deacon
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