Thread (15 messages) 15 messages, 4 authors, 2012-01-27

Re: [linux-pm] PM: cannot hibernate -- BUG at kernel/workqueue.c:3659

From: Srivatsa S. Bhat <hidden>
Date: 2012-01-25 15:31:44
Also in: lkml

On 01/25/2012 05:40 AM, Rafael J. Wysocki wrote:
On Wednesday, January 25, 2012, Jiri Slaby wrote:
quoted
On 01/25/2012 12:02 AM, Rafael J. Wysocki wrote:
quoted
On Tuesday, January 24, 2012, Jiri Slaby wrote:
quoted
On 01/24/2012 11:36 PM, Rafael J. Wysocki wrote:
quoted
On Tuesday, January 24, 2012, Jiri Slaby wrote:
quoted
On 01/24/2012 05:18 PM, Srivatsa S. Bhat wrote:
quoted
Hi Jiri,

On 01/24/2012 08:35 PM, Jiri Slaby wrote:
quoted
Hi,

this is a freshly booted system. When I do s2dsk, I see:
...
Freezing remaining freezable tasks ... BUG: 'workqueue_freezing' is true!
------------[ cut here ]------------
kernel BUG at /l/latest/linux/kernel/workqueue.c:3659!
invalid opcode: 0000 [#1] SMP
CPU 0
Modules linked in:

Pid: 2669, comm: s2disk Not tainted 3.3.0-rc1-next-20120124_64+ #1627
Bochs Bochs
RIP: 0010:[<ffffffff8107e365>]  [<ffffffff8107e365>]
freeze_workqueues_begin+0x195/0x1a0
RSP: 0018:ffff880046f01d68  EFLAGS: 00010292
RAX: 0000000000000023 RBX: 0000000000000001 RCX: 00000000000000c9
RDX: 0000000000000077 RSI: 0000000000000046 RDI: ffffffff81b51f7c
RBP: ffff880046f01d98 R08: ffffffff81a9d760 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 00007fff579464dc R14: ffffffffffffffff R15: 0000000000000004
FS:  00007f3c65d54700(0000) GS:ffff880049600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007f3c64f58c20 CR3: 0000000045b64000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process s2disk (pid: 2669, threadinfo ffff880046f00000, task
ffff880047251980)
Stack:
 ffff880046f01d98 0000000000000001 0000000000000000 00007fff579464dc
 ffffffffffffffff 0000000000000004 ffff880046f01e18 ffffffff81096cb9
 00000000ffff0124 0000000000000004 ffff880046f01e18 000000004f1ec7d1
Call Trace:
 [<ffffffff81096cb9>] try_to_freeze_tasks+0x1b9/0x2d0
 [<ffffffff81096ed5>] freeze_kernel_threads+0x25/0x90
 [<ffffffff81097b55>] hibernation_snapshot+0x75/0x2e0
 [<ffffffff8109d724>] snapshot_ioctl+0x314/0x4e0
 [<ffffffff81130856>] do_vfs_ioctl+0x96/0x550
 [<ffffffff8111ff7b>] ? vfs_write+0x10b/0x180
 [<ffffffff81130d5a>] sys_ioctl+0x4a/0x80
 [<ffffffff81630e22>] system_call_fastpath+0x16/0x1b
Code: c7 c6 0a a4 92 81 48 c7 c7 16 65 92 81 31 c0 e8 19 94 5a 00 0f 0b
48 c7 c6 27 a4 92 81 48 c7 c7 16 65 92 81 31 c0 e8 02 94 5a 00 <0f> 0b
66 0f 1f 84 00 00 00 00 00 55 48 c7 c7 82 4b b9 81 48 89
RIP  [<ffffffff8107e365>] freeze_workqueues_begin+0x195/0x1a0
 RSP <ffff880046f01d68>
---[ end trace 632574abdc098963 ]---

I couldn't find any obvious root-cause from a quick check. Is this completely
reproducible upon a fresh boot?
True.

The cause is that the function is called twice:
Which function?
The one where the BUG is. Maybe the functions which should clear the
flag is not called in between? See:
quoted
quoted
 [<ffffffff8107e206>] freeze_workqueues_begin+0x36/0x1b0
                         ^^^^^^^^^^^^^^^^^^^^^^^
quoted
quoted
 [<ffffffff81096cc9>] try_to_freeze_tasks+0x1b9/0x2d0
 [<ffffffff81096ee5>] freeze_kernel_threads+0x25/0x90
 [<ffffffff81097b65>] hibernation_snapshot+0x75/0x2e0
 [<ffffffff8109d734>] snapshot_ioctl+0x314/0x4e0
 [<ffffffff81130866>] do_vfs_ioctl+0x96/0x550
 [<ffffffff8111ff8b>] ? vfs_write+0x10b/0x180
 [<ffffffff81130d6a>] sys_ioctl+0x4a/0x80
 [<ffffffff81630e22>] system_call_fastpath+0x16/0x1b
(elapsed 0.03 seconds) done.
...
quoted
quoted
Freezing remaining freezable tasks ... BUG: 'workqueue_freezing' is true!
------------[ cut here ]------------
kernel BUG at /l/latest/linux/kernel/workqueue.c:3659!
...
quoted
quoted
RIP: 0010:[<ffffffff8107e371>]  [<ffffffff8107e371>
freeze_workqueues_begin+0x1a1/0x1b0
   ^^^^^^^^^^^^^^^^^^^^^^^
quoted
quoted
Call Trace:
 [<ffffffff81096cc9>] try_to_freeze_tasks+0x1b9/0x2d0
 [<ffffffff81096ee5>] freeze_kernel_threads+0x25/0x90
 [<ffffffff81097b65>] hibernation_snapshot+0x75/0x2e0
 [<ffffffff8109d734>] snapshot_ioctl+0x314/0x4e0
 [<ffffffff81130866>] do_vfs_ioctl+0x96/0x550
 [<ffffffff8111ff8b>] ? vfs_write+0x10b/0x180
 [<ffffffff81130d6a>] sys_ioctl+0x4a/0x80
 [<ffffffff81630e22>] system_call_fastpath+0x16/0x1b
Ah.  So this is linux-next, right?
Right.
quoted
Can you please test the linux-next branch of the linux-pm tree and see if
the problem is reproducible in there?
Yeah, 100%. Just try it with a small enough swap.
Ah, thanks, so that's an error code path problem and most likely in the Linus'
tree.

Srivatsa, any ideas?

Ok, I will need to quote a part of the userspace utility to explain the
problem.

In suspend.c inside the suspend-utils userspace package, I see a loop such
as:

        error = freeze(snapshot_fd);
	...
        attempts = 2;
        do {
                if (set_image_size(snapshot_fd, image_size)) {
                        error = errno;
                        break;
                }
                if (atomic_snapshot(snapshot_fd, &in_suspend)) {
                        error = errno;
                        break;
                }
                if (!in_suspend) {
                        /* first unblank the console, see console_codes(4) */
                        printf("\e[13]");
                        printf("%s: returned to userspace\n", my_name);
                        free_snapshot(snapshot_fd);
                        break;
                }

                error = write_image(snapshot_fd, resume_fd, -1);
                if (error) {
                        free_swap_pages(snapshot_fd);
                        free_snapshot(snapshot_fd);
                        image_size = 0;
                        error = -error;
                        if (error != ENOSPC)
                                break;
                } else {
                        splash.progress(100);
#ifdef CONFIG_BOTH
                        if (s2ram_kms || s2ram) {
                                /* If we die (and allow system to continue)
                                 * between now and reset_signature(), very bad
                                 * things will happen. */
                                error = suspend_to_ram(snapshot_fd);
                                if (error)
                                        goto Shutdown;
                                reset_signature(resume_fd);
                                free_swap_pages(snapshot_fd);
                                free_snapshot(snapshot_fd);
                                if (!s2ram_kms)
                                        s2ram_resume();
                                goto Unfreeze;
                        }
Shutdown:
#endif
                        close(resume_fd);
                        suspend_shutdown(snapshot_fd);
                }
        } while (--attempts);

...
Unfreeze:
        unfreeze(snapshot_fd);


Let me reply to this thread so that I can comment on the above code.

Regards,
Srivatsa S. Bhat
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