On 2017/5/24 9:40, Xishi Qiu wrote:
> Hi, I find we use rcu access task_struct in mm_match_cgroup(), but not use
> rcu free in free_task_struct(), is it right?
>
> Here is the backtrace.
>
> PID: 2133 TASK: ffff881fe3353300 CPU: 2 COMMAND: "CPU 15/KVM"
> #0 [ffff881fe276b528] machine_kexec at ffffffff8105280b
> #1 [ffff881fe276b588] crash_kexec at ffffffff810f5072
> #2 [ffff881fe276b658] panic at ffffffff8163e23b
> #3 [ffff881fe276b6d8] oops_end at ffffffff8164d61b
> #4 [ffff881fe276b700] die at ffffffff8101872b
> #5 [ffff881fe276b730] do_general_protection at ffffffff8164cefe
> #6 [ffff881fe276b760] general_protection at ffffffff8164c7a8
> [exception RIP: mem_cgroup_from_task+22]
> RIP: ffffffff811db536 RSP: ffff881fe276b810 RFLAGS: 00010286
> RAX: 6b6b6b6b6b6b6b6b RBX: ffffea007f988880 RCX: 0000000000020000
> RDX: 00000007fa607d67 RSI: 00000007fa607d67 RDI: ffff880fe36d72c0
> RBP: ffff881fe276b880 R8: 00000007fa607600 R9: a801fd67b3000000
> R10: 57fdec98cc59ecc0 R11: ffff880fe2e8dbd0 R12: ffffc9001cb74000
> R13: ffff881fdb8cfda0 R14: ffff881fe2581570 R15: 00000007fa607d67
> ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0000
> #7 [ffff881fe276b810] page_referenced at ffffffff811a6b8a
> #8 [ffff881fe276b888] shrink_page_list at ffffffff81180994
> #9 [ffff881fe276b9c0] shrink_inactive_list at ffffffff8118166a
> #10 [ffff881fe276ba88] shrink_lruvec at ffffffff81182135
> #11 [ffff881fe276bb88] shrink_zone at ffffffff81182596
> #12 [ffff881fe276bbe0] do_try_to_free_pages at ffffffff81182a90
> #13 [ffff881fe276bc58] try_to_free_mem_cgroup_pages at ffffffff81182fea
> #14 [ffff881fe276bcf0] mem_cgroup_reclaim at ffffffff811dd8de
> #15 [ffff881fe276bd30] __mem_cgroup_try_charge at ffffffff811ddd9c
> #16 [ffff881fe276bdf0] __mem_cgroup_try_charge_swapin at ffffffff811df62b
> #17 [ffff881fe276be28] mem_cgroup_try_charge_swapin at ffffffff811e0537
> #18 [ffff881fe276be38] handle_mm_fault at ffffffff8119abdd
> #19 [ffff881fe276bec8] __do_page_fault at ffffffff816502d6
> #20 [ffff881fe276bf28] do_page_fault at ffffffff81650603
> #21 [ffff881fe276bf50] page_fault at ffffffff8164c808
> RIP: 00007fdaba456500 RSP: 00007fdaaba6c978 RFLAGS: 00010246
> RAX: ffffffffffffffff RBX: 0000000000000000 RCX: fffffffffffffbd0
> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 000000000000002c
> RBP: 00007fdaaba6c9f0 R8: 0000000000840c70 R9: 00000000000000be
> R10: 000000007fffffff R11: 0000000000000246 R12: 0000000003622010
> R13: 000000000000ae80 R14: 00000000008274e0 R15: 0000000003622010
> ORIG_RAX: ffffffffffffffff CS: 0033 SS: 002b
>
>
> .
>
