ion and not the first one. Since our next function will return NULL at the end, the iter passed to cio_ignore_proc_seq_stop is NULL. The original iter has leaked. The solution is to use seq_open_private. Found with kmemleak: unreferenced object 0x1c720580 (size 32): comm "head", pid 973, jiffies 4294958302 hex dump (first 32 bytes): 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<0000000000203154>] kmem_cache_alloc+0x190/0x19c [<00000000003fb462>] cio_ignore_proc_seq_start+0x5e/0x128 [<0000000000231018>] seq_read+0xc8/0x4bc [<0000000000273954>] proc_reg_read+0xa8/0xf4 [<000000000020e3d8>] vfs_read+0xac/0x1a4 [<000000000020e5c6>] SyS_read+0x52/0xa8 [<000000000011836e>] sysc_noemu+0x10/0x16 [<0000004690b7936c>] 0x4690b7936c Signed-off-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky r*ßU›"x