Kernel panic in find_vma() function.

Issue

• Kernel panic by reading /proc/$$/numa_maps file as a non-priviledged user.

Eg:

$ cat /proc/$$/numa_maps

• Kernel panic in find_vma() function with following call traces.

[2064085.258298] general protection fault: 0000 [#1] SMP 
[2064085.264183] last sysfs file: /sys/devices/pci0000:c0/0000:c0:05.2/class
[2064085.271863] CPU 8 
[2064085.274114] Modules linked in: mri_mm(U) bonding 8021q garp stp llc ipv6 mlx4_en(U) mlx4_core(U) be2net(U) ext3 jbd cdc_ether usbnet mii microcode iTCO_wdt iTCO_vendor_support i2c_i801 i2c_core shpchp ioatdma dca ses enclosure sg ext4 mbcache jbd2 usb_storage sd_mod crc_t10dif wmi megaraid_sas(U) dm_mirror dm_region_hash dm_log dm_mod [last unloaded: be2net]
[2064085.311280] 
[2064085.313246] Pid: 5442, comm: cat Not tainted 2.6.32-358.15.1.el6.x86_64 #1 IBM System x3750 M4 -[8722AC1]-/00D1471
[2064085.325266] RIP: 0010:[<ffffffff81146e87>]  [<ffffffff81146e87>] find_vma+0x17/0x80
[2064085.334247] RSP: 0018:ffff8832e9289d08  EFLAGS: 00010202
[2064085.340483] RAX: 0ff889484e74ff85 RBX: 0000000000400000 RCX: 00000000004d3fff
[2064085.348851] RDX: 0000007fffffffff RSI: 0000000000400000 RDI: ffffffff811e7380
[2064085.357218] RBP: ffff8832e9289d08 R08: ffffffff8179dedc R09: 0000000000000fe0
[2064085.365591] R10: 0000000000000005 R11: 0000000000000fe9 R12: 00000000004d4000
[2064085.373963] R13: ffff8832e9289db8 R14: 8100000001b93870 R15: 0000008000000000
[2064085.382423] FS:  00007f94732ab700(0000) GS:ffff8810b8880000(0000) knlGS:0000000000000000
[2064085.391871] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[2064085.398591] CR2: 0000000001b28068 CR3: 000000388972a000 CR4: 00000000000407a0
[2064085.406965] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[2064085.415338] DR3: 0000000000000000 DR6: 00000000ffff4ff0 DR7: 0000000000000400
[2064085.423715] Process cat (pid: 5442, threadinfo ffff8832e9288000, task ffff88339c26e040)
[2064085.433068] Stack:
[2064085.435617]  ffff8832e9289d88 ffffffffa02c9161 ffff8832e9289d58 ffffffff811a4cae
[2064085.444038] <d> ffff883069583c80 ffff882051008a40 ffff8814ac667016 00000000004d3fff
[2064085.453076] <d> 00000000004d4000 0000007fffffffff ffff8832e9289d88 ffff88281cff2380
[2064085.464394] Call Trace:
[2064085.467437]  [<ffffffffa02c9161>] az_walk_page_range+0x101/0x4a0 [mri_mm]
[2064085.475324]  [<ffffffff811a4cae>] ? mangle_path+0x8e/0xc0
[2064085.481674]  [<ffffffff811e7652>] show_numa_map+0x142/0x3f0
[2064085.488210]  [<ffffffff811e7a70>] ? gather_pte_stats+0x0/0x200
[2064085.495024]  [<ffffffff811e7380>] ? gather_hugetbl_stats+0x0/0x70
[2064085.502139]  [<ffffffff8150fbb6>] ? down_read+0x16/0x30
[2064085.508321]  [<ffffffff811e7e27>] ? m_start+0xb7/0x160
[2064085.514364]  [<ffffffff811a5342>] seq_read+0xf2/0x400
[2064085.520311]  [<ffffffff81181a95>] vfs_read+0xb5/0x1a0
[2064085.526261]  [<ffffffff81181bd1>] sys_read+0x51/0x90
[2064085.532124]  [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b
[2064085.539136] Code: 68 8b 40 30 c9 83 f0 01 83 e0 01 c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 0f 1f 44 00 00 48 85 ff 74 6a 48 8b 47 10 48 85 c0 74 06 <48> 39 70 10 77 43 48 8b 57 08 48 85 d2 74 52 31 c0 eb 18 66 0f 
[2064085.561780] RIP  [<ffffffff81146e87>] find_vma+0x17/0x80
[2064085.568034]  RSP <ffff8832e9289d08>