linux-kernel - [PATCH] iommu: Properly pass gfp_t in _iommu

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Date:   Mon,  1 Feb 2021 17:06:23 -0800
From:   Douglas Anderson <dianders@...omium.org>
To:     Yong Wu <yong.wu@...iatek.com>, Will Deacon <will@...nel.org>,
        joro@...tes.org
Cc:     Douglas Anderson <dianders@...omium.org>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH] iommu: Properly pass gfp_t in _iommu_map() to avoid atomic sleeping

Sleeping while atomic = bad.  Let's fix an obvious typo to try to avoid it.

The warning that was seen (on a downstream kernel with the problematic
patch backported):

 BUG: sleeping function called from invalid context at mm/page_alloc.c:4726
 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 9, name: ksoftirqd/0
 CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 5.4.93-12508-gc10c93e28e39 #1
 Call trace:
  dump_backtrace+0x0/0x154
  show_stack+0x20/0x2c
  dump_stack+0xa0/0xfc
  ___might_sleep+0x11c/0x12c
  __might_sleep+0x50/0x84
  __alloc_pages_nodemask+0xf8/0x2bc
  __arm_lpae_alloc_pages+0x48/0x1b4
  __arm_lpae_map+0x124/0x274
  __arm_lpae_map+0x1cc/0x274
  arm_lpae_map+0x140/0x170
  arm_smmu_map+0x78/0xbc
  __iommu_map+0xd4/0x210
  _iommu_map+0x4c/0x84
  iommu_map_atomic+0x44/0x58
  __iommu_dma_map+0x8c/0xc4
  iommu_dma_map_page+0xac/0xf0

Fixes: d8c1df02ac7f ("iommu: Move iotlb_sync_map out from __iommu_map")
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---
I haven't done any serious testing on this.  I saw a report of the
warning and the fix seemed obvious so I'm shooting it out.

 drivers/iommu/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 3d099a31ddca..2b06b01850d5 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2441,7 +2441,7 @@ static int _iommu_map(struct iommu_domain *domain, unsigned long iova,
 	const struct iommu_ops *ops = domain->ops;
 	int ret;
 
-	ret = __iommu_map(domain, iova, paddr, size, prot, GFP_KERNEL);
+	ret = __iommu_map(domain, iova, paddr, size, prot, gfp);
 	if (ret == 0 && ops->iotlb_sync_map)
 		ops->iotlb_sync_map(domain, iova, size);
 
-- 
2.30.0.365.g02bc693789-goog