Re: oops in fs/dcache.c:536 with 3.4.107

Re: oops in fs/dcache.c:536 with 3.4.107

[Daniel Wittmer]

<adding linux-fsdevel>

On Thu, May 21, 2015 at 5:39 PM, Daniel Wittmer <wittmer@google.com> wrote:
> <adding Al>
>
> Hi Al,
>
> I was wondering if the above oops (fs/dcache.c:536 in v7.4.107) was
> what you were seeing for the "RCU pathwalk breakage when running into
> a symlink overmounting something" issue
> (https://lkml.org/lkml/2015/5/2/488) you recently fixed, or if this is
> a diferent issue?
>
> Thanks in advance,
> Dan
>
> On Wed, May 20, 2015 at 5:03 PM, Daniel Wittmer <wittmer@google.com> wrote:
>> Hi all,
>>
>> We've recently started to encounter the below oops in fs/dcache.c:536
>> on a few machines running 3.4.107. Looking into changes to dcache.h/c
>> and fs/namei.c I'm not seeing any changes that may have caused or
>> addressed this issue.
>>
>> Is this a known oops? Is there a fix in later versions that I may have missed?
>>
>> Thanks in advance,
>> Dan
>>
>> ------------[ cut here ]------------
>> kernel BUG at fs/dcache.c:536!
>> invalid opcode: 0000 [#1] SMP
>> CPU 1
>> Modules linked in:
>>
>> Pid: 22588, comm: <snip> Not tainted 3.4.107<snip>
>> RIP: 0010:[<ffffffff810eaf8e>]  [<ffffffff810eaf8e>] dput+0x1be/0x1c0
>> RSP: 0018:ffff8817c24cdc18  EFLAGS: 00010246
>> RAX: 0000000000000000 RBX: ffff88183683ac48 RCX: 0000000000006564
>> RDX: 0000000000006464 RSI: 0000000000000011 RDI: ffff88183683aca8
>> RBP: ffff8817c24cdc38 R08: 0000000000000000 R09: ffff88183682df08
>> R10: ffff88183682ded0 R11: 0000000000000009 R12: ffff88177229c3f5
>> R13: ffff8818368e7d20 R14: ffff88183683aca8 R15: 0000000000000003
>> FS:  00007feaade39700(0000) GS:ffff88183f220000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00007feabdec6000 CR3: 000000170ed8f000 CR4: 00000000000407e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
>> Process longplanner_wor (pid: 22588, threadinfo ffff8817c24cc000, task
>> ffff8817c1df8080)
>> Stack:
>> ffff8817c24cddc8 ffff88177229c3f5 ffff8818368e7d20 ffff8817c1df8080
>> ffff8817c24cdcf8 ffffffff810e1569 ffff88183683ac48 ffff88183683aca8
>> ffff8817c39c79c0 ffff88183683ac48 ffff8817c24cdc78 ffff8817c1df8080
>> Call Trace:
>>  [<ffffffff810e1569>] link_path_walk+0x2a9/0x8a0
>>  [<ffffffff810e24bf>] path_lookupat+0x36f/0x6f0
>>  [<ffffffff810e286b>] do_path_lookup+0x2b/0x70
>>  [<ffffffff810e4154>] user_path_at_empty+0x54/0xa0
>>  [<ffffffff810d9874>] ? cp_new_stat+0xf4/0x110
>>  [<ffffffff810e41ac>] user_path_at+0xc/0x10
>>  [<ffffffff810d9a15>] vfs_fstatat+0x35/0x60
>>  [<ffffffff810d9a76>] vfs_stat+0x16/0x20
>>  [<ffffffff810d9b85>] sys_newstat+0x15/0x30
>>  [<ffffffff814e42a2>] system_call_fastpath+0x16/0x1b
>> Code: 00 48 8d 90 20 01 00 00 48 89 93 a0 00 00 00 4c 89 a0 20 01 00
>> 00 48 8b 83 80 00 00 00 83 80 30 01 00 00 01 e8 24 89 3f 00 eb 8b <0f>
>> 0b 55 48 89 e5 41 57 41 56 4c 8d 7f 78 49 89 fe 41 55 4c 8d
>> RIP  [<ffffffff810eaf8e>] dput+0x1be/0x1c0
>>  RSP <ffff8817c24cdc18>
>> ---[ end trace 835aa73d3e65f5b3 ]---