Re: (unionfs) panic: excl->share with r230341 and above

> Hi
>
> Please try an attached patch that improves handlings of fs locks.
> I think that this patch can resolve this issue. If that works well,
> I'm going to refine and commit it to head.
>

Thanks!

I tried your patch but get the same panic:

    FreeBSD 10.0-CURRENT #6 r233856M: Mon Apr  9 09:47:42 EDT 2012
    ...
    exclusive lock of (lockmgr) ufs _at_
/usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1897
    while share locked from /usr/src/sys/modules/unionfs/../../fs/unionfs/
union_vnops.c:1897
    panic: excl->share
    cpuid = 0
    KDB: enter: panic
    [ thread pid 38 tid 100050 ]
    Stopped at      kdb_enter+0x3b: movl    $0,kdb_why
    db> show all locks
    Process 38 (ls) thread 0xc56dd2e0 (100050)
    exclusive sleep mutex vnode interlock (vnode interlock) r = 0
(0xc5797d38) locked _at_
/usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1889
    shared lockmgr ufs (ufs) r = 0 (0xc5797d18) locked _at_
/usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1897
    db>

> On Fri, 6 Apr 2012 21:36:29 -0400 (EDT)
> kwhite_at_site.uottawa.ca wrote:
>> Starting with r230341, I get the following panic when trying to run
>> an executable on a unionfs filesystem:
>>
>>         exclusive lock of (lockmgr) ufs _at_
>> /usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1843
>>         while share locked from
>> /usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1843
>>         panic: excl->share
>>         cpuid = 0
>>         KDB: enter: panic
>>
>> Narrowing down with a binary search: r230340 (no panic), r230341
>> (panic).
>>
>> How to repeat:
>>         # uuname -a
>>         FreeBSD  10.0-CURRENT FreeBSD 10.0-CURRENT #5 r233946M: Fri Apr
>> 6
>> 21:09:32 EDT 2012     kwhite_at_demo:/usr/src/obj/usr/src/sys/GENERIC
>>  i386
>>
>>         # mkdir /tmp/local
>>         # mount -t unionfs -o noatime /tmp/local /usr/local
>>         # cp /bin/ls /usr/local/bin/ls
>>         # /usr/local/bin/ls
>>         ....
>>         exclusive lock of (lockmgr) ufs _at_
>> /usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1843
>>         while share locked from
>> /usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1843
>>         panic: excl->share
>>         cpuid = 0
>>         KDB: enter: panic
>>         [ thread pid 68 tid 100054 ]
>>         Stopped at      kdb_enter+0x3b: movl    $0,kdb_why
>>         db> show all locks
>>         Process 68 (ls) thread 0xc5780000 (100054)
>>         exclusive sleep mutex vnode interlock (vnode interlock) r = 0
>> (0xc57cec28) locked _at_
>> /usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1835
>>         shared lockmgr ufs (ufs) r = 0 (0xc57cec08) locked _at_
>> /usr/src/sys/modules/unionfs/../../fs/unionfs/union_vnops.c:1843
>>         db>
>>
>> Workaround?
>>         After reverting the change from LK_EXCLUSIVE to LK_SHARED
>>         in sys/kern/kern_exec.c, executables on union filesystems no
>>         longer cause a panic.
>>
>> ...keith
>>
>>
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>
>
> --
> Daichi GOTO (daichi)
> FreeBSD Committer, http://www.FreeBSD.org The Power To Serve
>