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Groups > linux.kernel > #1273993

[RFC PATCH v2] iommu/amd: gray the 'irq_remap_table' object for kmemleak

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The kmemleak testing on 3.18.24 show:

unreferenced object 0xffff880233ff9010 (size 16):
  comm "swapper/0", pid 1, jiffies 4294937440 (age 2010.490s)
  hex dump (first 16 bytes):
    0a 0a 00 00 20 00 00 00 00 44 fb 33 02 88 ff ff  .... ....D.3....
  backtrace:
    [<ffffffff8118192d>] create_object+0x10d/0x2d0
    [<ffffffff815c2d4b>] kmemleak_alloc+0x5b/0xc0
    [<ffffffff8116dd19>] kmem_cache_alloc_trace+0xb9/0x160
    [<ffffffff814ffe51>] get_irq_table+0x151/0x380

This is caused by the 'irq_lookup_table' was allocated with
__get_free_pages() which won't create kmemleak object, thus it's
pointers won't be count as referencing 'irq_remap_table' in
kmemleak scan.

The 'irq_remap_table' won't be freed after initialized, doesn't
make sense to check it's leaking.

This patch mark the 'irq_remap_table' object as 'gray' to stop
the 'false positives' report.

Signed-off-by: Michael Wang <yun.wang@profitbricks.com>
---
v2:
  Use kmemleak_not_leak() instead of kmemleak_ignore() since
  the 'irq_remap_table' itself also contain pointer.

 drivers/iommu/amd_iommu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 8b2be1e..87a1a88 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -3603,6 +3603,7 @@ static struct irq_remap_table *get_irq_table(u16 devid, bool ioapic)
 	}
 
 	irq_lookup_table[devid] = table;
+	kmemleak_not_leak(table);
 	set_dte_irq_entry(devid, table);
 	iommu_flush_dte(iommu, devid);
 	if (devid != alias) {
-- 
2.1.4

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[RFC PATCH] iommu/amd: make kmemleak ignore the 'irq_remap_table'  object Michael Wang <yun.wang@profitbricks.com> - 2015-11-20 12:10 +0100
  [RFC PATCH v2] iommu/amd: gray the 'irq_remap_table' object for  kmemleak Michael Wang <yun.wang@profitbricks.com> - 2015-11-20 12:40 +0100
    Re: [RFC PATCH v2] iommu/amd: gray the 'irq_remap_table' object for  kmemleak Michael Wang <yun.wang@profitbricks.com> - 2015-11-20 13:40 +0100
    Re: [RFC PATCH v2] iommu/amd: gray the 'irq_remap_table' object for  kmemleak Michael Wang <yun.wang@profitbricks.com> - 2015-11-25 12:20 +0100
    Re: [RFC PATCH v2] iommu/amd: gray the 'irq_remap_table' object for  kmemleak Joerg Roedel <joro@8bytes.org> - 2015-11-25 16:10 +0100
      Re: [RFC PATCH v2] iommu/amd: gray the 'irq_remap_table' object for  kmemleak Michael Wang <yun.wang@profitbricks.com> - 2015-11-25 16:20 +0100

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