Hi Johannes, On 01/20/2015 10:31 AM, Johannes Weiner wrote: > Introduce the basic control files to account, partition, and limit > memory using cgroups in default hierarchy mode. I'm seeing the following while fuzzing: [ 5634.427361] GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN [ 5634.430492] Dumping ftrace buffer: [ 5634.430565] (ftrace buffer empty) [ 5634.430565] Modules linked in: [ 5634.430565] CPU: 0 PID: 3983 Comm: kswapd0 Not tainted 3.19.0-next-20150222-sasha-00045-g8dc7569 #1943 [ 5634.430565] task: ffff88056a7cb000 ti: ffff880568860000 task.ti: ffff880568860000 [ 5634.430565] RIP: mem_cgroup_low (./arch/x86/include/asm/atomic64_64.h:21 include/asm-generic/atomic-long.h:31 include/linux/page_counter.h:34 mm/memcontrol.c:5438) [ 5634.430565] RSP: 0000:ffff880568867968 EFLAGS: 00010202 [ 5634.430565] RAX: 000000000000001a RBX: 0000000000000000 RCX: 0000000000000000 [ 5634.430565] RDX: 1ffff1000822a3a4 RSI: ffff880041151bd8 RDI: ffff880041151cb8 [ 5634.430565] RBP: ffff880568867998 R08: 0000000000000000 R09: 0000000000000001 [ 5634.430565] R10: ffff880041151bd8 R11: 0000000000000000 R12: 00000000000000d0 [ 5634.430565] R13: dffffc0000000000 R14: ffff8800000237b0 R15: 0000000000000000 [ 5634.430565] FS: 0000000000000000(0000) GS:ffff88091aa00000(0000) knlGS:0000000000000000 [ 5634.430565] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 5634.430565] CR2: 000000000138efd8 CR3: 0000000500078000 CR4: 00000000000007b0 [ 5634.430565] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 5634.430565] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 [ 5634.430565] Stack: [ 5634.430565] ffff880568867988 ffff880041151bd8 0000000000000000 ffff880000610000 [ 5634.430565] ffff880568867d68 dffffc0000000000 ffff880568867b38 ffffffff81a1ac0f [ 5634.430565] ffffffff81b875b0 1ffff100ad10cf45 ffff880568867d80 ffff880568867d70 [ 5634.430565] Call Trace: [ 5634.430565] shrink_zone (mm/vmscan.c:2389) [ 5634.430565] ? percpu_ref_get_many (include/linux/percpu-refcount.h:270) [ 5634.430565] ? shrink_lruvec (mm/vmscan.c:2365) [ 5634.430565] kswapd (mm/vmscan.c:3104 mm/vmscan.c:3276 mm/vmscan.c:3484) [ 5634.430565] ? debug_check_no_locks_freed (kernel/locking/lockdep.c:3051) [ 5634.430565] ? mem_cgroup_shrink_node_zone (mm/vmscan.c:3401) [ 5634.430565] ? __tick_nohz_task_switch (./arch/x86/include/asm/paravirt.h:809 (discriminator 2) kernel/time/tick-sched.c:292 (discriminator 2)) [ 5634.430565] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2554 kernel/locking/lockdep.c:2601) [ 5634.430565] ? trace_hardirqs_on (kernel/locking/lockdep.c:2609) [ 5634.430565] ? finish_task_switch (kernel/sched/core.c:2229) [ 5634.430565] ? finish_task_switch (kernel/sched/sched.h:1058 kernel/sched/core.c:2210) [ 5634.430565] ? __init_waitqueue_head (kernel/sched/wait.c:292) [ 5634.430565] ? __schedule (kernel/sched/core.c:2320 kernel/sched/core.c:2778) [ 5634.430565] ? mem_cgroup_shrink_node_zone (mm/vmscan.c:3401) [ 5634.430565] ? mem_cgroup_shrink_node_zone (mm/vmscan.c:3401) [ 5634.430565] kthread (kernel/kthread.c:207) [ 5634.430565] ? __tick_nohz_task_switch (./arch/x86/include/asm/paravirt.h:809 (discriminator 2) kernel/time/tick-sched.c:292 (discriminator 2)) [ 5634.430565] ? flush_kthread_work (kernel/kthread.c:176) [ 5634.430565] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2554 kernel/locking/lockdep.c:2601) [ 5634.430565] ? schedule_tail (kernel/sched/core.c:2268) [ 5634.430565] ? flush_kthread_work (kernel/kthread.c:176) [ 5634.430565] ret_from_fork (arch/x86/kernel/entry_64.S:283) [ 5634.430565] ? flush_kthread_work (kernel/kthread.c:176) [ 5634.430565] Code: ff 49 39 de 0f 84 bd 00 00 00 49 89 dc 49 81 c4 d0 00 00 00 0f 84 f7 00 00 00 41 f6 c4 07 0f 85 ed 00 00 00 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 0f 85 ef 00 00 00 4c 8b a3 d0 00 00 00 48 85 db All code ======== 0: ff 49 39 decl 0x39(%rcx) 3: de 0f fimul (%rdi) 5: 84 bd 00 00 00 49 test %bh,0x49000000(%rbp) b: 89 dc mov %ebx,%esp d: 49 81 c4 d0 00 00 00 add $0xd0,%r12 14: 0f 84 f7 00 00 00 je 0x111 1a: 41 f6 c4 07 test $0x7,%r12b 1e: 0f 85 ed 00 00 00 jne 0x111 24: 4c 89 e0 mov %r12,%rax 27: 48 c1 e8 03 shr $0x3,%rax 2b:* 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 30: 0f 85 ef 00 00 00 jne 0x125 36: 4c 8b a3 d0 00 00 00 mov 0xd0(%rbx),%r12 3d: 48 85 db test %rbx,%rbx ... Code starting with the faulting instruction =========================================== 0: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) 5: 0f 85 ef 00 00 00 jne 0xfa b: 4c 8b a3 d0 00 00 00 mov 0xd0(%rbx),%r12 12: 48 85 db test %rbx,%rbx ... [ 5634.430565] RIP mem_cgroup_low (./arch/x86/include/asm/atomic64_64.h:21 include/asm-generic/atomic-long.h:31 include/linux/page_counter.h:34 mm/memcontrol.c:5438) [ 5634.430565] RSP <ffff880568867968> Thanks, Sasha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>