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nephros
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Joined: 07 Feb 2003
Posts: 2139
Location: Graz, Austria (Europe - no kangaroos.)
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 Posted: Sat Mar 12, 2005 1:35 pm Post subject: find: WARNING: Hard link count is wrong for /proc |
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Hi.
Today I encountered an error message the likes of which I have never seen before.
| Code: | [scourge]~ # find / -user <username>
find: WARNING: Hard link count is wrong for /proc: this may be a bug in your filesystem driver. Automatically turning on find's -noleaf option. Earlier results may have failed to include directories that should have been searched.
find: /proc/4310/task/4310/fd/4: No such file or directory
find: /proc/4310/fd/4: No such file or directory |
I understand that this is most likely harmless, /proc being a very special filesystem, but I am still curious what happens here. My theory is that the process with PID 4310 exited (or at least closed fd 4) while find was traversing /proc/4310, causing the kernel to remove that directory, which confused find.
I read the man page entry on -noleaf but it just added to the confusion.
Can anyone shed a light on this?
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cfd
n00b
Joined: 15 Jan 2004
Posts: 18
Location: Midwest, USA
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| Posted: Sat Mar 19, 2005 5:28 am Post subject: |
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I just got this one for the first time tonight as well.
I recently rebooted.
I get it repeatedly while searching / (root)
I don't get the last two specific 'find' errors, Just:
| Code: | | find: WARNING: Hard link count is wrong for /proc: this may be a bug in your filesystem driver. Automatically turning on find's -noleaf option. Earlier results may have failed to include directories that should have been searched. |
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anfpunk
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Joined: 29 May 2003
Posts: 275
Location: Columbus, Oh
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| Posted: Sun Mar 20, 2005 7:53 am Post subject: |
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Same thing here with 2.6.11-hardened-r1 on ext3.
I am only getting the first part as well. Not the no file errors. |
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Sandman.173rd.
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Joined: 20 Mar 2005
Posts: 4
Location: Germany
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| Posted: Sun Mar 20, 2005 3:53 pm Post subject: |
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Encountering same problem on ext3 FS with kernel 2.6.10 aswell as 2.6.11.3 (I tried a newer version in the hope of resolving this issue)
washington ~ # find / -name Search
find: WARNING: Hard link count is wrong for /proc: this may be a bug in your filesystem driver. Automatically turning on find's -noleaf option. Earlier results may have failed to include directories that should have been searched. |
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zeveck
Apprentice
Joined: 17 Mar 2005
Posts: 173
Location: Boston, MA
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| Posted: Sun Mar 20, 2005 8:26 pm Post subject: |
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| Encountering same problem with kernel linux-2.6.9-gentoo-r13 and ext3. =( |
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nephros
Advocate
Joined: 07 Feb 2003
Posts: 2139
Location: Graz, Austria (Europe - no kangaroos.)
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| Posted: Sun Mar 20, 2005 9:58 pm Post subject: |
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ext3 has nothing to do with it as /proc has a special filesystem not ext3.
Now I did a bit of researching on what a hard link count and a hard link is (namely what is usually called a directory), it's easy to show that find is actually right:
| Code: | [scourge]3345 # /bin/pwd
/proc/3345
[scourge]3345 # ls -la
total 0
dr-xr-xr-x 3 root root 0 Mar 20 22:21 .
dr-xr-xr-x 182 root root 0 Mar 20 14:57 ..
-r-------- 1 root root 0 Mar 20 22:21 auxv
-r--r--r-- 1 root root 0 Mar 20 22:21 cmdline
lrwxrwxrwx 1 root root 0 Mar 20 22:21 cwd -> /
-r-------- 1 root root 0 Mar 20 22:21 environ
lrwxrwxrwx 1 root root 0 Mar 20 22:21 exe -> /usr/sbin/syslogd
dr-x------ 2 root root 0 Mar 20 22:21 fd
-r--r--r-- 1 root root 0 Mar 20 22:21 maps
-rw------- 1 root root 0 Mar 20 22:21 mem
-r--r--r-- 1 root root 0 Mar 20 22:21 mounts
lrwxrwxrwx 1 root root 0 Mar 20 22:21 root -> /
-r--r--r-- 1 root root 0 Mar 20 22:21 stat
-r--r--r-- 1 root root 0 Mar 20 22:21 statm
-r--r--r-- 1 root root 0 Mar 20 22:21 status
dr-xr-xr-x 3 root root 0 Mar 20 22:21 task
-r--r--r-- 1 root root 0 Mar 20 22:21 wchan |
The second field in the ls -l output is the "hard link count", the number of directories in a dir. For /proc/<SOMEPID> dirs, this is always 3, but should be 4 because every such dir has ".", "..", "fd" and "task"
If you copy the <SOMEPID> dir onto a real filesystem, the hard link count shows up correct, 4:
| Code: | [scourge]3345 # cd /var/tmp
[scourge]tmp # cp -a /proc/3345/ .
cp: reading `/proc/3345/task/3345/mem': No such process
cp: reading `/proc/3345/mem': No such process
[scourge]tmp # cd 3345
[scourge]3345 # ls -la
total 37
dr-xr-xr-x 4 root root 408 Mar 20 22:21 .
drwxrwxrwt 17 root root 520 Mar 20 22:30 ..
-r-------- 1 root root 144 Mar 20 22:21 auxv
-r--r--r-- 1 root root 27 Mar 20 22:21 cmdline
lrwxrwxrwx 1 root root 1 Mar 20 22:30 cwd -> /
-r-------- 1 root root 375 Mar 20 22:21 environ
lrwxrwxrwx 1 root root 17 Mar 20 22:30 exe -> /usr/sbin/syslogd
dr-x------ 2 root root 576 Mar 20 22:21 fd
-r--r--r-- 1 root root 936 Mar 20 22:21 maps
-rw------- 1 root root 0 Mar 20 22:30 mem
-r--r--r-- 1 root root 831 Mar 20 22:21 mounts
lrwxrwxrwx 1 root root 1 Mar 20 22:30 root -> /
-r--r--r-- 1 root root 187 Mar 20 22:21 stat
-r--r--r-- 1 root root 21 Mar 20 22:21 statm
-r--r--r-- 1 root root 503 Mar 20 22:21 status
dr-xr-xr-x 3 root root 72 Mar 20 22:21 task
-r--r--r-- 1 root root 1 Mar 20 22:21 wchan |
Strange, strange...
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Sandman.173rd.
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anfpunk
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Joined: 29 May 2003
Posts: 275
Location: Columbus, Oh
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| Posted: Tue Mar 22, 2005 1:56 pm Post subject: |
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| Sandman.173rd. wrote: | https://bugs.gentoo.org/show_bug.cgi?id=86031
still waiting for a reply :evil: |
Still nothing on the bug. :( |
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nephros
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Joined: 07 Feb 2003
Posts: 2139
Location: Graz, Austria (Europe - no kangaroos.)
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| Posted: Tue Mar 22, 2005 3:39 pm Post subject: |
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Patience folks.
Its not like its in anyway critical or something.
It also looks like an upstream problem if it's a problem at all.
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Sandman.173rd.
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Joined: 20 Mar 2005
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| Posted: Sat Apr 02, 2005 10:42 am Post subject: |
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Seems to be resolved ... but how do I apply the attached patch?
patch -p ???? |
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Sandman.173rd.
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Joined: 20 Mar 2005
Posts: 4
Location: Germany
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| Posted: Sat Apr 02, 2005 11:55 am Post subject: |
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I have applied it by hand  |
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racoontje
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Joined: 19 Jul 2004
Posts: 1290
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| Posted: Sat Apr 02, 2005 12:02 pm Post subject: |
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| patch -p0, or other numbers depending on patchlevel |
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nephros
Advocate
Joined: 07 Feb 2003
Posts: 2139
Location: Graz, Austria (Europe - no kangaroos.)
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| Posted: Sat Apr 02, 2005 12:30 pm Post subject: |
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Hey a problem I found found its way up to Andrew Morton! Thats nice.
Thanks Sandman.173rd and dsd!
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dsd
Developer
Joined: 30 Mar 2003
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Location: nr London
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| Posted: Sat Apr 02, 2005 8:08 pm Post subject: |
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yeah- thanks! and you also made me realise another error case: /proc/<PID>/task always has a hardlink count of 3, which is obviously wrong for multithreaded apps which will have more than one child. sent in another patch to andrew.
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