Hi all,

I can reproduce this all the way back to 3.0 kernel.

show_uevent():
        /* copy keys to file */
        for (i = 0; i < env->envp_idx; i++)
                count += sprintf(&buf[count], "%s\n", env->envp[i]);

[   26.602710] warning: process `trinity-child0' used the deprecated sysctl system call with 
[   32.747503] general protection fault: 0000 [#1] DEBUG_PAGEALLOC
[   32.748700] CPU 0 
[   32.748700] Pid: 84, comm: trinity-child0 Not tainted 3.5.0-rc5+ #51 Bochs Bochs
[   32.748700] RIP: 0010:[<ffffffff8115a5bd>]  [<ffffffff8115a5bd>] strnlen+0xd/0x40
[   32.748700] RSP: 0018:ffff880005f87d08  EFLAGS: 00010286
[   32.748700] RAX: ffffffff81404ed8 RBX: ffff880005fa70e0 RCX: fffffffffffffffe
[   32.748700] RDX: 3a69706361000000 RSI: ffffffffffffffff RDI: 3a69706361000000
[   32.748700] RBP: ffff880005f87d08 R08: 000000000000ffff R09: 000000000000ffff
[   32.748700] R10: ffff880006e8b000 R11: ffff88000005ebc0 R12: 3a69706361000000
[   32.748700] R13: ffff880085fa70df R14: 000000000000ffff R15: 0000000000000000
[   32.748700] FS:  00007f177a9d2700(0000) GS:ffffffff81457000(0000) knlGS:0000000000000000
[   32.748700] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   32.748700] CR2: 0000000002f1b000 CR3: 0000000005f84000 CR4: 00000000000006b0
[   32.748700] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   32.748700] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[   32.748700] Process trinity-child0 (pid: 84, threadinfo ffff880005f86000, task ffff880006f6c440)
[   32.748700] Stack:
[   32.748700]  ffff880005f87d48 ffffffff8115ba8e ffff880006e8b103 ffff880005fa70e0
[   32.748700]  ffff880085fa70df ffff880005f87de0 ffffffff813eb7c4 ffffffff813eb7c4
[   32.748700]  ffff880005f87dc8 ffffffff8115c569 ffff880005f87e08 ffffffff810730eb
[   32.748700] Call Trace:
[   32.748700]  [<ffffffff8115ba8e>] string.isra.4+0x3e/0xd0
[   32.748700]  [<ffffffff8115c569>] vsnprintf+0x219/0x600
[   32.748700]  [<ffffffff810730eb>] ? __lock_acquire.isra.31+0x3eb/0xb30
[   32.748700]  [<ffffffff8115cd30>] sprintf+0x40/0x50
[   32.748700]  [<ffffffff811f0dbe>] show_uevent+0xee/0x120
[   32.748700]  [<ffffffff811118fe>] ? sysfs_read_file+0x3e/0x1a0
[   32.748700]  [<ffffffff811f0c8b>] dev_attr_show+0x1b/0x60
[   32.748700]  [<ffffffff81111946>] ? sysfs_read_file+0x86/0x1a0
[   32.748700]  [<ffffffff8109d7e8>] ? __get_free_pages+0x18/0x80
[   32.748700]  [<ffffffff81111972>] sysfs_read_file+0xb2/0x1a0
[   32.748700]  [<ffffffff810cd14f>] vfs_read+0x9f/0x160
[   32.748700]  [<ffffffff810cd4c8>] sys_read+0x48/0x90
[   32.748700]  [<ffffffff812b6637>] system_call_fastpath+0x16/0x1b
[   32.748700] Code: c0 01 80 38 00 75 f7 48 29 f8 5d c3 31 c0 5d c3 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 85 f6 48 8d 4e ff 48 89 e5 74 2a <80> 3f 00 74 25 48 89 f8 31 d2 eb 10 0f 1f 80 00 00 00 00 48 83 
[   32.748700] RIP  [<ffffffff8115a5bd>] strnlen+0xd/0x40
[   32.748700]  RSP <ffff880005f87d08>

Thanks,
Fengguang