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Subject[PATCH V2] megaraid: kmemleak: Track page allocation for fusion
Date
From: Shu Wang <shuwang@redhat.com>

Kmemleak reports about a thousand false positives for fusion->
cmd_list[]. Root casue is the cmd_list objects are allocated from
slab allocator, and stored its pointer in object allocated by page
allocator. The fix will tell kmemleak to track and scan fusion
object.

V2:
Add comment, balance braces, move kmemleak_free before free_pages.
checkpatch passed.

Before patch:
kmemleak: 1004 new suspected memory leaks (see /sys/kernel/debug/kmemleak)

unreferenced object 0xffff88042584e000 (size 8192):
backtrace:
kmemleak_alloc+0x4a/0xa0
__kmalloc+0xec/0x220
megasas_alloc_cmdlist_fusion+0x3e/0x140 [megaraid_sas]
megasas_alloc_cmds_fusion+0x44/0x450 [megaraid_sas]
megasas_init_adapter_fusion+0x21d/0x6e0 [megaraid_sas]
megasas_init_fw+0x357/0xd30 [megaraid_sas]
megasas_probe_one.part.34+0x5be/0x1040 [megaraid_sas]
megasas_probe_one+0x46/0xc0 [megaraid_sas]
local_pci_probe+0x45/0xa0
work_for_cpu_fn+0x14/0x20
process_one_work+0x149/0x360
worker_thread+0x1d8/0x3c0
kthread+0x109/0x140
ret_from_fork+0x25/0x30

Signed-off-by: Shu Wang <shuwang@redhat.com>
---
drivers/scsi/megaraid/megaraid_sas_fusion.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index 11bd2e698b84..161b8e5518c0 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -48,6 +48,7 @@
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/vmalloc.h>
+#include <linux/kmemleak.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
@@ -4512,6 +4513,13 @@ megasas_alloc_fusion_context(struct megasas_instance *instance)
dev_err(&instance->pdev->dev, "Failed from %s %d\n", __func__, __LINE__);
return -ENOMEM;
}
+ } else {
+ /*
+ * Allow kmemleak to scan these pages as they contain pointers
+ * to additional allocations. fusion->cmd_list[].
+ */
+ kmemleak_alloc(instance->ctrl_context,
+ sizeof(struct fusion_context), 1, GFP_KERNEL);
}

fusion = instance->ctrl_context;
@@ -4548,9 +4556,11 @@ megasas_free_fusion_context(struct megasas_instance *instance)

if (is_vmalloc_addr(fusion))
vfree(fusion);
- else
+ else {
+ kmemleak_free(fusion);
free_pages((ulong)fusion,
instance->ctrl_context_pages);
+ }
}
}

--
2.13.5
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