linux-kernel - Re: Regression introduced by bfcfaa77bdf0f775263e906015982a608df01c76 (vfs: use 'unsigned long' accesses for dcache name comparison and hashing)

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Date:	Thu, 22 Mar 2012 15:33:27 -0400
From:	Eric Paris <eparis@...isplace.org>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com
Subject: Re: Regression introduced by bfcfaa77bdf0f775263e906015982a608df01c76
 (vfs: use 'unsigned long' accesses for dcache name comparison and hashing)

No idea if it is related and haven't bisected, but we are seeing
similar ENOENT issues with things in selinuxfs.  And not a single bit
of SELinux code has changed since v3.3.  So it's certainly a VFS
problem.  This sounds likely.

-Eric

On Thu, Mar 22, 2012 at 2:38 PM, Konrad Rzeszutek Wilk
<konrad.wilk@...cle.com> wrote:
> Hey Linus,
>
> I am not sure how to debug this but with v3.3 with just that git commit I can't
> start an user space application called 'xenstored'. A bit of strace showed me:
> [edit, also with todays linus/master I get the same issue, and if I revert
> your patch it works again]
>
> (right is 3.3, left is with your patch)
> write(3, "Checking store complete.\n", 25) = 25                 write(3, "Checking store complete.\n", 25) = 25
> sendto(9, "<11>Mar 22 18:00:27 xenstored: C"..., 55, MSG_NOSI | sendto(9, "<11>Mar 22 18:06:44 xenstored: C"..., 55, MSG_NOSI
> open("/proc/xen/privcmd", O_RDWR)       = 10                    open("/proc/xen/privcmd", O_RDWR)       = 10
> fcntl(10, F_GETFD)                      = 0                     fcntl(10, F_GETFD)                      = 0
> fcntl(10, F_SETFD, FD_CLOEXEC)          = 0                     fcntl(10, F_SETFD, FD_CLOEXEC)          = 0
> open("/dev/xen/evtchn", O_RDWR)         = 11                    open("/dev/xen/evtchn", O_RDWR)         = 11
> open("/proc/xen/xsd_port", O_RDONLY)    = -1 ENOENT (No such  | open("/proc/xen/xsd_port", O_RDONLY)    = 12
> write(2, "FATAL: ", 7FATAL: )                  = 7            | read(12, "25", 20)                      = 2
> write(2, "Failed to initialize dom0 state:"..., 59Failed to i | close(12)                               = 0
> ) = 59                                                        | ioctl(11, EVIOCGVERSION, 0x7fff4e3ffc70) = 41
> close(10)                               = 0                   | write(3, "CREATE connection 0xe2e7b0\n", 27) = 27
> close(5)                                = 0                   | open("/proc/xen/xsd_kva", O_RDWR)       = 12
> close(4)                                = 0                   | mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, 12, 0) = 0
> exit_group(1)                           = ?                   | close(12)                               = 0
>                                                              > ioctl(11, EVIOCGKEYCODE or EVIOCSKEYCODE, 0x7fff4e3ffc90) = 0
>                                                              > ioctl(11, 0x44500, 0x7fff4e3ffc90)      = 42
>                                                              > rt_sigaction(SIGHUP, {0x402180, [HUP], SA_RESTORER|SA_RESTART
>                                                              > select(12, [4 5 6 11], [], NULL, NULL)  = 1 (in [11])
>                                                              > read(11, ")\0\0\0", 4)                  = 4
>                                                              > write(11, ")\0\0\0", 4)                 = 4
>                                                              > select(12, [4 5 6 11], [], NULL, NULL <unfinished ...>
>
> and if I ls /proc/xen (v3.3):
>
>> ls -al /proc/xen
> total 0
> drwxr-xr-x   2 root root 0 Mar 22 18:05 .
> dr-xr-xr-x 126 root root 0 Mar 22 18:05 ..
> -r--r--r--   1 root root 0 Mar 22 18:05 capabilities
> -rw-------   1 root root 0 Mar 22 18:05 privcmd
> -rw-------   1 root root 0 Mar 22 18:05 xenbus
> -rw-------   1 root root 0 Mar 22 18:05 xsd_port
>
> while v3.3 with your patch:
>
>
> 8:01:09 # 10 :/proc/xen/
>> ls -al
> ls: cannot access xsd_port: No such file or directory
> total 0
> drwxr-xr-x   2 root root 0 Mar 22 17:57 .
> dr-xr-xr-x 126 root root 0 Mar 22 17:57 ..
> -r--r--r--   1 root root 0 Mar 22 17:57 capabilities
> -rw-------   1 root root 0 Mar 22 17:57 privcmd
> -rw-------   1 root root 0 Mar 22 17:57 xenbus
> -rw-------   1 root root 0 Mar 22 17:57 xsd_kva
> -?????????   ? ?    ?    ?            ? xsd_port
>
>
> Looking at the code that sets up 'xsd_port' it looks pretty innocent
> and similar to other drivers (ibmasm for example).
>
> Also attached is the .config
>
> Note: to actually bootup the latest with Xen there are some fixes required
> to fix the regressions introduced:
> http://git.kernel.org/?p=linux/kernel/git/konrad/xen.git;a=commit;h=106b44388d8f76373149c4ea144f717b6d4d9a6d
> http://git.kernel.org/?p=linux/kernel/git/konrad/xen.git;a=commit;h=a759ceb7d1dfe38f4dda147e233aa53c8f477e2a
> http://git.kernel.org/?p=linux/kernel/git/konrad/xen.git;a=commit;h=1b34ba936c1adff3020eec1e1834ffa4cf89802f
> http://git.kernel.org/?p=linux/kernel/git/konrad/xen.git;a=commit;h=6ac72c4bc49a9afb02b8176b48be019dff0560cd
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