linux-kernel - [PATCH] iommu/io-pgtable-arm-v7s: only kmemleak

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Date:   Mon, 28 Jan 2019 17:43:01 +0800
From:   Nicolas Boichat <drinkcat@...omium.org>
To:     Will Deacon <will.deacon@....com>
Cc:     Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Catalin Marinas <catalin.marinas@....com>,
        stable@...r.kernel.org
Subject: [PATCH] iommu/io-pgtable-arm-v7s: only kmemleak_ignore L2 tables

L1 tables are allocated with __get_dma_pages, and therefore already
ignored by kmemleak.

Without this, the kernel would print this error message on boot,
when the first L1 table is allocated:

[    2.810533] kmemleak: Trying to color unknown object at 0xffffffd652388000 as Black
[    2.818190] CPU: 5 PID: 39 Comm: kworker/5:0 Tainted: G S                4.19.16 #8
[    2.831227] Workqueue: events deferred_probe_work_func
[    2.836353] Call trace:
...
[    2.852532]  paint_ptr+0xa0/0xa8
[    2.855750]  kmemleak_ignore+0x38/0x6c
[    2.859490]  __arm_v7s_alloc_table+0x168/0x1f4
[    2.863922]  arm_v7s_alloc_pgtable+0x114/0x17c
[    2.868354]  alloc_io_pgtable_ops+0x3c/0x78
...

Fixes: e5fc9753b1a8314 ("iommu/io-pgtable: Add ARMv7 short descriptor support")
Signed-off-by: Nicolas Boichat <drinkcat@...omium.org>
---

I only tested this on top of my other series
(https://patchwork.kernel.org/patch/10720495/), but I think the same fix
applies. I'm still a bit confused as to why this only shows up now, as IIUC,
the kmemleak_ignore call was always wrong with L1 tables.

 drivers/iommu/io-pgtable-arm-v7s.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
index cec29bf45c9bd7..98a4a4a0dfb0c1 100644
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -217,7 +217,8 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
 		if (dma != phys)
 			goto out_unmap;
 	}
-	kmemleak_ignore(table);
+	if (lvl == 2)
+		kmemleak_ignore(table);
 	return table;
 
 out_unmap:
-- 
2.20.1.495.gaa96b0ce6b-goog