Hello,
bug hit again with new gcc.
(one of my added) debug is
*** namespace.c 2014/02/21 14:41:22 1.1
--- namespace.c 2014/02/21 14:49:25
***************
*** 665,674 ****
--- 665,677 ----
static void put_mountpoint(struct mountpoint *mp)
{
+ DPRINTK("mp=%p");
+
if (!--mp->m_count) {
struct dentry *dentry = mp->m_dentry;
spin_lock(&dentry->d_lock);
dentry->d_flags &= ~DCACHE_MOUNTED;
+ DPRINTK("cleared mounted on dentry=%p %.*s",dentry,
dentry->d_name.len, dentry->d_name.name);
spin_unlock(&dentry->d_lock);
list_del(&mp->m_hash);
kfree(mp);
Here is an extract from the logfile from a successful dismount of
/package/sequencer:
939 2014-02-24T07:54:30.278237+01:00 kasslerbraten kernel: [
695.352155] pid 1425: autofs4_expire_indirect: checking mountpoint
ffff8800c2433c90 sequencer
940 2014-02-24T07:54:30.278238+01:00 kasslerbraten kernel: [
695.352157] pid 1425: autofs4_mount_busy: dentry ffff8800c2433c90
sequencer
941 2014-02-24T07:54:30.278239+01:00 kasslerbraten kernel: [
695.352159] pid 1425: autofs4_mount_busy: returning = 0
942 2014-02-24T07:54:30.278240+01:00 kasslerbraten kernel: [
695.352160] pid 1425: autofs4_expire_indirect: returning
ffff8800c2433c90 sequencer
943 2014-02-24T07:54:30.278241+01:00 kasslerbraten kernel: [
695.352161] pid 1425: autofs4_wait: new wait id = 0x0000000a, name =
sequencer, nfy=2
944 2014-02-24T07:54:30.278242+01:00 kasslerbraten kernel: [
695.352162] pid 1425: autofs4_notify_daemon: wait id = 0x0000000a,
name = sequencer, type=4
969 2014-02-24T07:54:30.312515+01:00 kasslerbraten kernel: [
695.386185] pid 1433: put_mountpoint: mp=ffff8800c9e215d0
970 2014-02-24T07:54:30.312527+01:00 kasslerbraten kernel: [
695.386188] pid 1433: put_mountpoint: cleared mounted on
dentry=ffff8800c2433c90 sequencer
971 2014-02-24T07:54:30+01:00 kasslerbraten automount[626]: expired
/package/sequencer
972 2014-02-24T07:54:30.324519+01:00 kasslerbraten kernel: [
695.398095] pid 1428: autofs4_dir_open: file=ffff880126f43ec0
dentry=ffff8800c2433c90 sequencer
973 2014-02-24T07:54:30.324531+01:00 kasslerbraten kernel: [
695.398105] pid 1428: autofs4_dentry_release: releasing ffff8800ad2d4a50
974 2014-02-24T07:54:30.324534+01:00 kasslerbraten kernel: [
695.398109] pid 1428: autofs4_dir_rmdir: dentry ffff8800c2433c90,
removing sequencer
975 2014-02-24T07:54:30.324536+01:00 kasslerbraten kernel: [
695.398157] pid 1425: autofs4_dentry_release: releasing ffff8800c2433c90
Here is an extract from the logfile from a failed dismount of
/package/sequencer:
91779 2014-02-26T14:13:16.157522+01:00 kasslerbraten kernel:
[196176.289030] pid 8739: autofs4_expire_indirect: checking mountpoint
ffff880046a45810 sequencer
91780 2014-02-26T14:13:16.157523+01:00 kasslerbraten kernel:
[196176.289033] pid 8739: autofs4_mount_busy: dentry ffff880046a45810
sequencer
91781 2014-02-26T14:13:16.157524+01:00 kasslerbraten kernel:
[196176.289034] pid 8739: autofs4_mount_busy: returning = 0
91782 2014-02-26T14:13:16.157525+01:00 kasslerbraten kernel:
[196176.289036] pid 8739: autofs4_expire_indirect: returning
ffff880046a45810 sequencer
91783 2014-02-26T14:13:16.157526+01:00 kasslerbraten kernel:
[196176.289039] pid 8739: autofs4_wait: new wait id = 0x00000085, name
= sequencer, nfy=2
91784 2014-02-26T14:13:16.157527+01:00 kasslerbraten kernel:
[196176.289040] pid 8739: autofs4_notify_daemon: wait id = 0x00000085,
name = sequencer, type=4
91785 2014-02-26T14:13:16.178496+01:00 kasslerbraten kernel:
[196176.310371] pid 8742: put_mountpoint: mp=ffff8800c9e215d0
91786 2014-02-26T14:13:16+01:00 kasslerbraten automount[626]: expired
/package/sequencer
91787 2014-02-26T14:13:16.183536+01:00 kasslerbraten kernel:
[196176.314881] pid 8740: autofs4_d_automount: dentry=ffff880046a45810
sequencer
91788 2014-02-26T14:13:16.183542+01:00 kasslerbraten kernel:
[196176.314883] pid 8740: autofs4_d_automount: dentry=ffff880046a45810
sequencer
91789 2014-02-26T14:13:16.183544+01:00 kasslerbraten kernel:
[196176.314884] pid 8740: autofs4_d_automount: dentry=ffff880046a45810
sequencer
91790 2014-02-26T14:13:16.183545+01:00 kasslerbraten kernel:
[196176.314885] pid 8740: autofs4_d_automount: dentry=ffff880046a45810
sequencer
( Full file from boot to shutdown with egrep
'automount|autofs|d_set_mounted|put_mountpoint' in
http://owww.molgen.mpg.de/~buczek/autofs-demo/kasslerbraten.2014-02-26.l )
Obviously, "cleared mounted on dentry" is missing.
It looks like we enter put_mountpoint() but don't get to dentry->d_flags
&= ~DCACHE_MOUNTED;
mp->m_count is not zero probably.
What does it mean? The mount is still locked but not in the mount hash?
Alas, the user has rebootet the system, I can not look at the mountpoint
struct in memory.
I don't understand the vfs models. Anyone? Ideas?
Regards
Donald
On 02/21/14 16:15, Donald Buczek wrote:
Hello,
I've taken your idea "Apart from a really odd compiler optimization or
bug" and compiled with gcc 4.8.2 (instead of 4.7.3)
Also I've put some additional DPRINTKs into the routines setting or
clearing DCACHE_MOUNTED
So lets wait for the next event .....
Regards
Donald
On 02/21/14 02:42, Ian Kent wrote:
On Thu, 2014-02-20 at 16:57 +0100, Donald Buczek wrote:
On 02/20/14 13:18, Ian Kent wrote:
On Thu, 2014-02-20 at 19:41 +0800, Ian Kent wrote:
1969 (gdb) print *(struct dentry *) 0xffff88007fd06c50
1970 $3 = {d_flags = 1523840, d_seq = {sequence = 4}, d_hash =
{next = 0xffff880214025c98, pprev = 0xffffc9000013d570}, d_parent
= 0xffff8800caa66810, d_name = {{{hash = 1876415966, len = 7},
hash_len = 31941187038}, name = 0xffff88007fd06c88 "gbrowse"},
d_inode = 0xffff8800961ad250, d_iname = "gbrowse", '\000'
<repeats 24 times>, d_lockref = {{lock_count = 8610971969, {
1971 lock = {{rlock = {raw_lock = {{head_tail = 21037377,
tickets = {head = 321, tail = 321}}}}}}, count = 2}}}, d_op =
0xffffffff81c45b40, d_sb = 0xffff880222a33800, d_time = 0,
d_fsdata = 0xffff8800ca443b80, d_lru = {next =
0xffff88007fd06cd0, prev = 0xffff88007fd06cd0}, d_u = {d_child =
{next = 0xffff88007fc9f420, prev = 0xffff8800caa668b0}, d_rcu = {
1972 next = 0xffff88007fc9f420, func =
0xffff8800caa668b0}}, d_subdirs = {next = 0xffff88007fd06cf0,
prev = 0xffff88007fd06cf0}, d_alias = {next = 0x0, pprev =
0xffff8800961ad360}}
I wonder if there's a struct mount for which this dentry is
mnt_mountpoint and if so what the value of m_count is for the struct
mountpoint of the struct mount?
No there isn't. Already checked in
http://owww.molgen.mpg.de/~buczek/autofs-demo/typescript.l lines 1795ff
Oh right, I forgot about that, must have been the seemingly endless list
of dentrys above it, ;)
LOL, and if there was a mount that's unlinked we'd never find it, but
yes, a ref counting problem would most likely leave it on the list.
Regards
Donald
--
Donald Buczek
buczek@xxxxxxxxxxxxx
Tel: +49 30 8413 1433
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