linux-kernel - Re: [2.6.34-git8][regression] massive polling problems with udevd and other processes

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Message-ID: <4BF83CBF.8080300@gmail.com>
Date:	Sat, 22 May 2010 13:21:19 -0700
From:	walt <w41ter@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Re: [2.6.34-git8][regression] massive polling problems with udevd
 and other processes

On 05/22/2010 12:35 PM, Shawn Starr wrote:
> Just built today's snapshot from linus's tree and have problems with udev
> using 100% cpu and KDE processes also pegging cpus.
>
> This is with Fedora 13 + snapshot kernel from git.
>
> Anyone else noticing this?

Yes, just bisected it to this:

commit a7cf4145bb86aaf85d4d4d29a69b50b688e2e49d
Author: Eric Paris <eparis@>
Date:   Fri May 14 11:44:10 2010 -0400

     anon_inode: set S_IFREG on the anon_inode

     anon_inode_mkinode() sets inode->i_mode = S_IRUSR | S_IWUSR;  This means
     that (inode->i_mode & S_IFMT) == 0.  This trips up some SELinux code that
     needs to determine if a given inode is a regular file, a directory, etc.
     The easiest solution is to just make sure that the anon_inode also sets
     S_IFREG.

     Signed-off-by: Eric Paris <eparis@>
     Signed-off-by: Al Viro <viro@>

udevd is busy polling anon_inode:

COMMAND PID USER   FD   TYPE             DEVICE SIZE/OFF    NODE NAME
udevd   695 root  txt    REG               8,21   117632 1523956 /sbin/udevd
udevd   695 root  mem    REG               8,21    51528 1234821 /lib64/libnss_files-2.11.1.so
udevd   695 root  mem    REG               8,21    43376 2052251 /lib64/libnss_nis-2.11.1.so
udevd   695 root  mem    REG               8,21    88880 2052264 /lib64/libnsl-2.11.1.so
udevd   695 root  mem    REG               8,21    31432 1234823 /lib64/libnss_compat-2.11.1.so
udevd   695 root  mem    REG               8,21  1399984 1234830 /lib64/libc-2.11.1.so
udevd   695 root  mem    REG               8,21   128424 1234829 /lib64/ld-2.11.1.so
udevd   695 root    0u   CHR                1,3      0t0     147 /dev/null
udevd   695 root    1u   CHR                1,3      0t0     147 /dev/null
udevd   695 root    2u   CHR                1,3      0t0     147 /dev/null
udevd   695 root    3u   REG               0,14     1133    1670 /dev/.udev/queue.bin
udevd   695 root    4u  unix 0xffff88011f2b3c80      0t0     274 socket
udevd   695 root    5u  sock                0,5      0t0     275 can't identify protocol
udevd   695 root    6r   REG                0,8        0      17 anon_inode
udevd   695 root    7u   REG                0,8        0      17 anon_inode
udevd   695 root    8u  unix 0xffff88011f2b3980      0t0     276 socket
udevd   695 root    9u  unix 0xffff88011f2b3680      0t0     277 socket

poll([{fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 5, -1) = 1 ([{fd=6, revents=POLLIN}])

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