On Wed, Feb 16, 2011 at 5:08 AM, Ian Kent <ra...@themaw.net> wrote:
> On Tue, 2011-02-15 at 16:11 -0200, Leonardo Chiquitto wrote:
>> On Tue, Feb 15, 2011 at 10:28 AM, Ian Kent <ra...@themaw.net> wrote:
>> > On Mon, 2011-02-14 at 21:28 -0800, Mike Marion wrote:
>> >> On Mon, Feb 14, 2011 at 07:37:01PM -0800, Ian Kent wrote:
>> >>
>> >> > That is kernel revision and autofs revision?
>> >>
>> >> 2.6.16.60-0.59.1 (Sles10 sp3 with an updated, but not bleeding edge,
>> >> patch).
>> >> autofs 5.0.5 with most of the patches up to a couple months ago. It's
>> >> hard to
>> >> get exacts because it's a PTF from Novell (we really pushed them to
>> >> upgrade to
>> >> 5.0.5) but it should be pretty much equal to the patch they just released
>> >> for
>> >> sle 11 sp1 that they're recommending as they default going forward.
>> >
>> > That make it hard, as you know.
>> >
>> > But I wouldn't mind spending a bit of time on it, if you can also.
>> >
>> > Let's assume that it's a user space problem for now.
>>
>> Here are the call traces for all automount processes on the kernel side:
>
> I think it's a user space problem.
>
> snip ...
>
>> And here are the call traces from the user land daemon:
>>
>> Thread 9 (Thread 4017):
>> #0 0x00002b56e465d6a8 in __lll_mutex_lock_wait () from
>> /lib64/libpthread.so.0
>> #1 0x00002b56e46599fb in _L_mutex_lock_92 () from /lib64/libpthread.so.0
>> #2 0x00002b56e4659455 in pthread_mutex_lock () from /lib64/libpthread.so.0
>> #3 0x00005555555746cd in master_mutex_lock () at master.c:49
>> #4 0x000055555555d260 in do_hup_signal (master=0x55555568d010,
>> age=1296063258)
>> at automount.c:1276
>> #5 0x0000555555560bd3 in statemachine (arg=<value optimized out>)
>> at automount.c:1354
>> #6 main (arg=<value optimized out>) at automount.c:2142
>>
>> Thread 8 (Thread 20702):
>> #0 0x00002b56e4dd62a7 in brk () from /lib64/libc.so.6
>> #1 0x0000555555577dfe in expire (logopt=2, cmd=<value optimized out>, fd=21,
>> ioctlfd=21, path=0x55555569ca20 "/usr2", arg=0x41c27ef4)
>> at dev-ioctl-lib.c:657
>> #2 0x0000555555577ebe in ioctl_expire (logopt=21, ioctlfd=-1,
>> path=0x55555569ca20 "/usr2", when=0) at dev-ioctl-lib.c:701
>> #3 0x0000555555561e4e in expire_proc_indirect (arg=<value optimized out>)
>> at indirect.c:545
>> #4 0x00002b56e4657193 in start_thread () from /lib64/libpthread.so.0
>> #5 0x00002b56e4ddcdfd in sysctl () from /lib64/libc.so.6
>> #6 0x0000000000000000 in ?? ()
>>
>> Thread 7 (Thread 7060):
>> #0 0x00002b56e465ac77 in pthread_rwlock_wrlock () from
>> /lib64/libpthread.so.0
>> #1 0x00005555555752ea in master_source_writelock (entry=<value optimized
>> out>)
>> at master.c:527
>> #2 0x0000555555575f8f in master_add_map_source (entry=0x5555556a10b0,
>> type=0x0, format=0x0, age=1296059657, argc=1, argv=<value optimized out>)
>> at master.c:191
>> #3 0x0000555555579ee3 in master_parse_entry (buffer=<value optimized out>,
>> default_timeout=86400, logging=<value optimized out>, age=1296059657)
>> at master_parse.y:823
>> #4 0x00002aaaaaab83fe in lookup_read_master (master=<value optimized out>,
>> age=1296059657, context=<value optimized out>) at lookup_ldap.c:1625
>> #5 0x0000555555569052 in do_read_master (master=0x55555568d010,
>> type=<value optimized out>, age=1296059657) at lookup.c:96
>> #6 0x000055555556aa3c in lookup_nss_read_master (master=0x55555568d010,
>> age=1296059657) at lookup.c:229
>> #7 0x0000555555575c28 in master_read_master (master=0x55555568d010,
>> age=1296059657, readall=1) at master.c:831
>> #8 0x000055555555d844 in do_read_master (arg=<value optimized out>)
>> at automount.c:1259
>> #9 0x00002b56e4657193 in start_thread () from /lib64/libpthread.so.0
>> #10 0x00002b56e4ddcdfd in sysctl () from /lib64/libc.so.6
>> #11 0x0000000000000000 in ?? ()
>>
>> Thread 6 (Thread 6851):
>> #0 0x00002b56e465aa3d in pthread_rwlock_rdlock () from
>> /lib64/libpthread.so.0
>> #1 0x000055555556deb6 in cache_readlock (mc=0x55555568e5b8) at cache.c:60
>> #2 0x000055555556baff in do_readmap (arg=<value optimized out>) at
>> state.c:479
>> #3 0x00002b56e4657193 in start_thread () from /lib64/libpthread.so.0
>> #4 0x00002b56e4ddcdfd in sysctl () from /lib64/libc.so.6
>> #5 0x0000000000000000 in ?? ()
>>
>> Thread 5 (Thread 4026):
>> #0 0x00002b56e465d6a8 in __lll_mutex_lock_wait () from
>> /lib64/libpthread.so.0
>> #1 0x00002b56e46599fb in _L_mutex_lock_92 () from /lib64/libpthread.so.0
>> #2 0x00002b56e4659455 in pthread_mutex_lock () from /lib64/libpthread.so.0
>> #3 0x00005555555746cd in master_mutex_lock () at master.c:49
>> #4 0x0000555555560ff9 in handle_packet_missing_indirect (ap=0x55555569c940,
>> pkt=0x41823ec0) at indirect.c:808
>> #5 0x000055555555fa32 in handle_packet (ap=<value optimized out>)
>> at automount.c:1026
>> #6 handle_mounts (ap=<value optimized out>) at automount.c:1551
>> #7 0x00002b56e4657193 in start_thread () from /lib64/libpthread.so.0
>> #8 0x00002b56e4ddcdfd in sysctl () from /lib64/libc.so.6
>> #9 0x0000000000000000 in ?? ()
>>
>> Thread 4 (Thread 4025):
>> #0 0x00002b56e4dd4b26 in fts_read () from /lib64/libc.so.6
>> #1 0x00007fff37314e80 in ?? ()
>> #2 0x0000000000000000 in ?? ()
>>
>> Thread 3 (Thread 4022):
>> #0 0x00002b56e465ac77 in pthread_rwlock_wrlock () from
>> /lib64/libpthread.so.0
>> #1 0x00005555555752ea in master_source_writelock (entry=<value optimized
>> out>)
>> at master.c:527
>> #2 0x00005555555631af in handle_packet_missing_direct (ap=0x5555556a11c0,
>> pkt=0x40821ec0) at direct.c:1296
>> #3 0x000055555555fa1d in handle_packet (ap=<value optimized out>)
>> at automount.c:1029
>> #4 handle_mounts (ap=<value optimized out>) at automount.c:1551
>> #5 0x00002b56e4657193 in start_thread () from /lib64/libpthread.so.0
>> #6 0x00002b56e4ddcdfd in sysctl () from /lib64/libc.so.6
>> #7 0x0000000000000000 in ?? ()
>>
>> Thread 2 (Thread 4019):
>> #0 0x00002b56e465b326 in pthread_cond_wait@@GLIBC_2.3.2 ()
>> from /lib64/libpthread.so.0
>> #1 0x000055555556c8b3 in st_queue_handler (arg=<value optimized out>)
>> at state.c:1104
>> #2 0x00002b56e4657193 in start_thread () from /lib64/libpthread.so.0
>> #3 0x00002b56e4ddcdfd in sysctl () from /lib64/libc.so.6
>> #4 0x0000000000000000 in ?? ()
>>
>> Thread 1 (Thread 4018):
>> #0 0x00002b56e465b517 in pthread_cond_timedwait@@GLIBC_2.3.2 ()
>> from /lib64/libpthread.so.0
>> #1 0x0000555555573762 in alarm_handler (arg=<value optimized out>)
>> at alarm.c:206
>> #2 0x00002b56e4657193 in start_thread () from /lib64/libpthread.so.0
>> #3 0x00002b56e4ddcdfd in sysctl () from /lib64/libc.so.6
>> #4 0x0000000000000000 in ?? ()
>>
>
> It looks like a lock ordering bug to me and I think it's the same hang
> that Steve Thompson reported.
>
> This will be hard to test I think, hopefully Mike or Steve will be able
> to use a couple of machines for testing, even so it may take a while
> before we know.
>
> Could you prepare a test package for Mike using this patch please.
> It should apply OK but of course you'll need to discard or fix the
> CHANGELOG hunk.
>
> I'll prepare a test package for Steve soon as I get time.
>
> autofs-5.0.5 - fix out of order locking in readmap
>
> From: Ian Kent <ra...@themaw.net>
>
> When re-reading the master map and a mount lookup for a particular map
> entry arrives at the same time a map source is being added to the map
> entry and a map entry re-read is also initiated at the same time an
> out of order mutex locking bug which results in a hang.
> ---
>
> CHANGELOG | 1 +
> lib/master.c | 8 ++------
> 2 files changed, 3 insertions(+), 6 deletions(-)
>
>
> diff --git a/CHANGELOG b/CHANGELOG
> index 11054da..631094f 100644
> --- a/CHANGELOG
> +++ b/CHANGELOG
> @@ -55,6 +55,7 @@
> - add external bind method.
> - fix add simple bind auth.
> - add option to dump configured automount maps.
> +- fix out of order locking in readmap.
>
> 03/09/2009 autofs-5.0.5
> -----------------------
> diff --git a/lib/master.c b/lib/master.c
> index 95bd3fb..daedf66 100644
> --- a/lib/master.c
> +++ b/lib/master.c
> @@ -611,8 +611,6 @@ struct master_mapent *master_find_mapent(struct master
> *master, const char *path
> {
> struct list_head *head, *p;
>
> - master_mutex_lock();
> -
> head = &master->mounts;
> list_for_each(p, head) {
> struct master_mapent *entry;
> @@ -625,8 +623,6 @@ struct master_mapent *master_find_mapent(struct master
> *master, const char *path
> }
> }
>
> - master_mutex_unlock();
> -
> return NULL;
> }
>
> @@ -703,9 +699,7 @@ struct master_mapent *master_new_mapent(struct master
> *master, const char *path,
>
> void master_add_mapent(struct master *master, struct master_mapent *entry)
> {
> - master_mutex_lock();
> list_add_tail(&entry->list, &master->mounts);
> - master_mutex_unlock();
> return;
> }
>
> @@ -813,6 +807,7 @@ int master_read_master(struct master *master, time_t age,
> int readall)
> * We need to clear and re-populate the null map entry cache
> * before alowing anyone else to use it.
> */
> + master_mutex_lock();
> if (master->nc) {
> cache_writelock(master->nc);
> nc = master->nc;
> @@ -831,6 +826,7 @@ int master_read_master(struct master *master, time_t age,
> int readall)
> master_init_scan();
> lookup_nss_read_master(master, age);
> cache_unlock(nc);
> + master_mutex_unlock();
>
> if (!master->read_fail)
> master_mount_mounts(master, age, readall);
Hello Ian,
I just got a reply confirming that the hangs are no longer
reproducible with this
patch applied. Please, do you think you can consider it for upstream inclusion?
Thanks,
Leonardo
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