linux-kernel - Possible Memory Leak in KCOV Linux 4.15-rc1

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Message-ID: <CAASgV=tW5gDF8-bq_t+LYNaoLOnCbL94_u8+uF=s36-JNaGP_w@mail.gmail.com>
Date:   Fri, 19 Jan 2018 11:29:00 -0800
From:   Shankara Pailoor <sp3485@...umbia.edu>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Possible Memory Leak in KCOV Linux 4.15-rc1

Hi Dmitry,

I added support for kcov in strace and I have been tracing a fairly
large program but after a little while, I notice that when I mmap a
new cover buffer, the call fails with ENOMEM. After killing the
program, I try and rerun and I notice that there is nearly no memory
on the system. When I do a kmemleak scan I get the following reports:

I believe the problem occurs when I try and setup the kcov buffer
again after an exec. Instead of reusing the old file descriptor I open
kcov again within that process. In that case, I don't know what
happens to the old kcov struct.

I don't see a maintainers list for kcov so I decided to email you
directly. Let me know what more information I can provide.

unreferenced object 0xffff8800633f6378 (size 96):
  comm "runltp", pid 1847, jiffies 4294957922 (age 190.320s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc90008679000 (size 134217728):
  comm "runltp", pid 1847, jiffies 4294957981 (age 190.261s)
  hex dump (first 32 bytes):
    e0 d2 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  ..F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff8800633f6a58 (size 96):
  comm "runltp", pid 1848, jiffies 4294958935 (age 189.307s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc9001067a000 (size 134217728):
  comm "runltp", pid 1848, jiffies 4294958994 (age 189.248s)
  hex dump (first 32 bytes):
    76 db 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  v.F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88006516c6e8 (size 96):
  comm "runltp", pid 1849, jiffies 4294960010 (age 188.242s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc9001867b000 (size 134217728):
  comm "runltp", pid 1849, jiffies 4294960071 (age 188.181s)
  hex dump (first 32 bytes):
    5d ee 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  ].F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88003ed519d0 (size 96):
  comm "runltp", pid 1850, jiffies 4294961128 (age 187.124s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc900206bd000 (size 134217728):
  comm "runltp", pid 1850, jiffies 4294961186 (age 187.066s)
  hex dump (first 32 bytes):
    b8 e3 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  ..F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88003ed50c10 (size 96):
  comm "runltp", pid 1851, jiffies 4294962256 (age 186.004s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc900286ff000 (size 134217728):
  comm "runltp", pid 1851, jiffies 4294962315 (age 185.946s)
  hex dump (first 32 bytes):
    15 af 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  ..F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
root@...kaller:~# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff8800633f6378 (size 96):
  comm "runltp", pid 1847, jiffies 4294957922 (age 362.452s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc90008679000 (size 134217728):
  comm "runltp", pid 1847, jiffies 4294957981 (age 362.393s)
  hex dump (first 32 bytes):
    e0 d2 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  ..F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff8800633f6a58 (size 96):
  comm "runltp", pid 1848, jiffies 4294958935 (age 361.439s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc9001067a000 (size 134217728):
  comm "runltp", pid 1848, jiffies 4294958994 (age 361.380s)
  hex dump (first 32 bytes):
    76 db 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  v.F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88006516c6e8 (size 96):
  comm "runltp", pid 1849, jiffies 4294960010 (age 360.369s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc9001867b000 (size 134217728):
  comm "runltp", pid 1849, jiffies 4294960071 (age 360.308s)
  hex dump (first 32 bytes):
    5d ee 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  ].F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88003ed519d0 (size 96):
  comm "runltp", pid 1850, jiffies 4294961128 (age 359.251s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc900206bd000 (size 134217728):
  comm "runltp", pid 1850, jiffies 4294961186 (age 359.193s)
  hex dump (first 32 bytes):
    b8 e3 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  ..F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88003ed50c10 (size 96):
  comm "runltp", pid 1851, jiffies 4294962256 (age 358.132s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<ffffffff9acb9ea6>] kmem_cache_alloc_trace+0x146/0x2e0
    [<ffffffff9aa13575>] kcov_open+0x25/0x80
    [<ffffffff9b28d8f4>] open_proxy_open+0x1e4/0x2b0
    [<ffffffff9acd7f52>] do_dentry_open+0x682/0xd70
    [<ffffffff9acdbc17>] vfs_open+0x107/0x230
    [<ffffffff9ad1edd7>] path_openat+0x1157/0x3520
    [<ffffffff9ad2424b>] do_filp_open+0x25b/0x3b0
    [<ffffffff9acdcaac>] do_sys_open+0x4fc/0x6c0
    [<ffffffff9acdcc9d>] SyS_open+0x2d/0x40
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffc900286ff000 (size 134217728):
  comm "runltp", pid 1851, jiffies 4294962315 (age 358.073s)
  hex dump (first 32 bytes):
    15 af 46 00 00 00 00 00 22 05 73 81 ff ff ff ff  ..F.....".s.....
    47 16 73 81 ff ff ff ff 11 16 73 81 ff ff ff ff  G.s.......s.....
  backtrace:
    [<ffffffff9ac67fc7>] __vmalloc_node_range+0x387/0x6a0
    [<ffffffff9ac6844c>] vmalloc_user+0x6c/0x140
    [<ffffffff9aa1320e>] kcov_mmap+0x2e/0x170
    [<ffffffff9ac48ecc>] mmap_region+0xa9c/0x15a0
    [<ffffffff9ac4a096>] do_mmap+0x6c6/0xe10
    [<ffffffff9abd773e>] vm_mmap_pgoff+0x1de/0x270
    [<ffffffff9ac40889>] SyS_mmap_pgoff+0x469/0x610
    [<ffffffff9a66d066>] SyS_mmap+0x16/0x20
    [<ffffffff9a60733b>] do_syscall_64+0x23b/0x820
    [<ffffffff9cf8e01d>] return_from_SYSCALL_64+0x0/0x75
    [<ffffffffffffffff>] 0xffffffffffffffff