task containersv11 kernel BUG at include/linux/dcache.h:323

[Paul Jackson <pj@sgi.com>]

Paul Menage,

When I run a cpuset creation/destruction stress test I have
against the 2.6.23-rc4-mm1 kernel with the task-containersv11-*
patches, I get an BUG or similar within a couple of seconds,
apparently over some fs lock or count confusions.

When I add Andrew Morton's (Thanks, Andrew!) very recent patch:

--- 2.6.23-rc4-mm1.orig/fs/dcache.c     2007-09-14 21:30:19.504902465 -0700
+++ 2.6.23-rc4-mm1/fs/dcache.c  2007-09-15 09:48:40.306230196 -0700
@@ -176,6 +176,7 @@ void dput(struct dentry *dentry)
        if (!dentry)
                return;

+       WARN_ON_ONCE(!atomic_read(&dentry->d_count));
 repeat:
        if (atomic_read(&dentry->d_count) == 1)
                might_sleep();

... then I get a warning first from the above line, resulting
in the following messages, showing the warning and then the
subsequent BUG:

Sep 15 21:41:45 margin kernel: WARNING: at fs/dcache.c:179 dput()
Sep 15 21:41:45 margin kernel:
Sep 15 21:41:45 margin kernel: Call Trace:
Sep 15 21:41:45 margin kernel:  [<a0000001000139c0>] show_stack+0x40/0xa0
Sep 15 21:41:45 margin kernel:                                 sp=e00000b05003fbd0 bsp=e00000b050038e20
Sep 15 21:41:45 margin kernel:  [<a000000100013a50>] dump_stack+0x30/0x60
Sep 15 21:41:45 margin kernel:                                 sp=e00000b05003fda0 bsp=e00000b050038e08
Sep 15 21:41:45 margin kernel:  [<a0000001001a60c0>] dput+0xa0/0x420
Sep 15 21:41:45 margin kernel:                                 sp=e00000b05003fda0 bsp=e00000b050038dd8
Sep 15 21:41:45 margin kernel:  [<a000000100193f00>] do_rmdir+0x160/0x200
Sep 15 21:41:45 margin kernel:                                 sp=e00000b05003fda0 bsp=e00000b050038da0
Sep 15 21:41:45 margin kernel:  [<a000000100194070>] sys_rmdir+0x30/0x60
Sep 15 21:41:45 margin kernel:                                 sp=e00000b05003fe30 bsp=e00000b050038d48
Sep 15 21:41:45 margin kernel:  [<a00000010000af80>] ia64_ret_from_syscall+0x0/0x20
Sep 15 21:41:45 margin kernel:                                 sp=e00000b05003fe30 bsp=e00000b050038d48
Sep 15 21:41:45 margin kernel:  [<a000000000010620>] __kernel_syscall_via_break+0x0/0x20
Sep 15 21:41:45 margin kernel:                                 sp=e00000b050040000 bsp=e00000b050038d48
Sep 15 21:41:46 margin kernel: kernel BUG at include/linux/dcache.h:323!
Sep 15 21:41:46 margin kernel: cpuset_creation[5590]: bugcheck! 0 [1]
Sep 15 21:41:46 margin kernel: Modules linked in:
Sep 15 21:41:46 margin kernel:
Sep 15 21:41:46 margin kernel: Pid: 5590, CPU 0, comm:      cpuset_creation
Sep 15 21:41:46 margin kernel: psr : 00001010085a6010 ifs : 800000000000048c ip  : [<a000000100193280>]    Not tainted
Sep 15 21:41:46 margin kernel: ip is at do_path_lookup+0x480/0x540
Sep 15 21:41:46 margin kernel: unat: 0000000000000000 pfs : 000000000000048c rsc : 0000000000000003
Sep 15 21:41:46 margin kernel: rnat: 0000000000000000 bsps: 0000000000000000 pr  : 000000000055a959
Sep 15 21:41:46 margin kernel: ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c0270033f
Sep 15 21:41:46 margin kernel: csd : 0000000000000000 ssd : 0000000000000000
Sep 15 21:41:46 margin kernel: b0  : a000000100193280 b6  : a000000100093960 b7  : a00000010000f0b0
Sep 15 21:41:46 margin kernel: f6  : 1003e0000000000000000 f7  : 000000000000000000000
Sep 15 21:41:46 margin kernel: f8  : 000000000000000000000 f9  : 1003e000000000001c000
Sep 15 21:41:46 margin kernel: f10 : 1003e0000000000000070 f11 : 1003e0000000000000400
Sep 15 21:41:46 margin kernel: r1  : a000000101074460 r2  : e000003016fa0ce0 r3  : 0000000000000002
Sep 15 21:41:46 margin kernel: r8  : 000000000000002d r9  : 0000000000004000 r10 : e000003003105619
Sep 15 21:41:46 margin kernel: r11 : e000003003110000 r12 : e000003016fa7d80 r13 : e000003016fa0000
Sep 15 21:41:46 margin kernel: r14 : 0000000000000000 r15 : e000003016fa0cf0 r16 : e000003016fa0d08
Sep 15 21:41:46 margin kernel: r17 : e00001b008397e18 r18 : 0000000000000001 r19 : e00000300310561b
Sep 15 21:41:46 margin kernel: r20 : 0000000000004000 r21 : 0000000000004000 r22 : e000003003110000
Sep 15 21:41:46 margin kernel: r23 : ffffffffffff0428 r24 : 0000018110000380 r25 : 0000018000000000
Sep 15 21:41:46 margin kernel: r26 : e000003016fa0cf0 r27 : e000003016fa0ce0 r28 : e000003016fa0d08
Sep 15 21:41:46 margin kernel: r29 : 0000000000000001 r30 : 0000000000000002 r31 : 0000000000001060
Sep 15 21:41:46 margin kernel:
Sep 15 21:41:46 margin kernel: Call Trace:
Sep 15 21:41:46 margin kernel:  [<a0000001000139c0>] show_stack+0x40/0xa0
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7950 bsp=e000003016fa10d0
Sep 15 21:41:47 margin kernel:  [<a0000001000142c0>] show_regs+0x840/0x880
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7b20 bsp=e000003016fa1078
Sep 15 21:41:47 margin kernel:  [<a0000001000362a0>] die+0x220/0x300
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7b20 bsp=e000003016fa1030
Sep 15 21:41:47 margin kernel:  [<a0000001000363d0>] die_if_kernel+0x50/0x80
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7b20 bsp=e000003016fa1000
Sep 15 21:41:47 margin kernel:  [<a000000100037af0>] ia64_bad_break+0x230/0x480
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7b20 bsp=e000003016fa0fd0
Sep 15 21:41:47 margin kernel:  [<a00000010000b120>] ia64_leave_kernel+0x0/0x280
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7bb0 bsp=e000003016fa0fd0
Sep 15 21:41:47 margin kernel:  [<a000000100193280>] do_path_lookup+0x480/0x540
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7d80 bsp=e000003016fa0f70
Sep 15 21:41:47 margin kernel:  [<a000000100194ac0>] __path_lookup_intent_open+0x80/0x120
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7d90 bsp=e000003016fa0f18
Sep 15 21:41:47 margin kernel:  [<a000000100194c60>] path_lookup_open+0x40/0x60
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7d90 bsp=e000003016fa0ed8
Sep 15 21:41:47 margin kernel:  [<a000000100194f30>] open_namei+0xb0/0xf80
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7d90 bsp=e000003016fa0e70
Sep 15 21:41:47 margin kernel:  [<a000000100177a10>] do_filp_open+0x50/0xc0
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7da0 bsp=e000003016fa0e38
Sep 15 21:41:47 margin kernel:  [<a000000100177b00>] do_sys_open+0x80/0x1c0
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7e30 bsp=e000003016fa0de0
Sep 15 21:41:47 margin kernel:  [<a000000100177d10>] sys_open+0x50/0x80
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7e30 bsp=e000003016fa0d88
Sep 15 21:41:47 margin kernel:  [<a00000010000af80>] ia64_ret_from_syscall+0x0/0x20
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa7e30 bsp=e000003016fa0d88
Sep 15 21:41:47 margin kernel:  [<a000000000010620>] __kernel_syscall_via_break+0x0/0x20
Sep 15 21:41:47 margin kernel:                                 sp=e000003016fa8000 bsp=e000003016fa0d88
Sep 15 21:41:47 margin kernel: note: cpuset_creation[5590] exited with preempt_count 1

===

Can you figure out where this is coming from?  It is not
in code that I understand all that well, so I am hoping
that I don't have to spend hours poking around in it to
make sense of the problem.

-- 
                          I won't rest till it's the best ...
                          Programmer, Linux Scalability
                          Paul Jackson <pj@sgi.com> 1.650.933.1373
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/