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SubjectRe: [PATCH] PM / Freezer: Freeze filesystems while freezing processes (v2)
test results of the patch below:

1. real machine

suspends fine but on wakeup, after loading image: hard reset.
nvidia gpu => disabled compitz => wakeup worked two times.


2. virtualbox / stress test / xfs and ext4

on 3rd resume, it booted up "normal" like this:

[ 3.351813] Freeing unused kernel memory: 568k freed
[ 3.460973] Freeing unused kernel memory: 284k freed

[ 17.328356] PM: Preparing processes for restore.

[ 17.328357] Freezing user space processes ...
[ 37.345414] Freezing of tasks failed after 20.01 seconds (1 tasks
refusing to freeze, wq_busy=0):
[ 37.475244] ffff88001f06fd68 0000000000000086 0000000000000000
0000000000000000
[ 37.526163] ffff88001f06e010 ffff88001f4c4410 0000000000012ec0
ffff88001f06ffd8
[ 37.580110] ffff88001f06ffd8 0000000000012ec0 ffffffff8160d020
ffff88001f4c4410
[ 37.626167] Call Trace:
[ 37.626769] [<ffffffff81049944>] schedule+0x55/0x57
[ 37.674925] [<ffffffff81360dbe>] __mutex_lock_common+0x117/0x178
[ 37.792559] [<ffffffff81113ef2>] ? user_path_at+0x61/0x90
[ 37.888501] [<ffffffff81360e35>] __mutex_lock_slowpath+0x16/0x18
[ 37.986966] [<ffffffff81360efb>] mutex_lock+0x1e/0x32
[ 38.086931] [<ffffffffa00a4d43>] show_manufacturer+0x23/0x51 [usbcore]
[ 38.212500] [<ffffffff8125cd44>] dev_attr_show+0x22/0x49
[ 38.282319] [<ffffffff810c6f8c>] ? __get_free_pages+0x9/0x38
[ 38.397449] [<ffffffff8115febb>] sysfs_read_file+0xa9/0x12b
[ 38.491607] [<ffffffff81107ff6>] vfs_read+0xa6/0x102
[ 38.541994] [<ffffffff81105ebf>] ? do_sys_open+0xee/0x100
[ 38.564907] [<ffffffff8110810b>] sys_read+0x45/0x6c
[ 38.578397] [<ffffffff81368412>] system_call_fastpath+0x16/0x1b
[ 38.590083]
[ 38.598046] Restarting tasks ... done.
[ 38.660448] XFS (sda3): Mounting Filesystem
restarted the test runs, increased delay between awake and sleep from 20
to 25 sec:

36 time successful hibernate+resume so far.


chris



On 25.09.2011 00:56, Rafael J. Wysocki wrote:
> On Sunday, August 07, 2011, Dave Chinner wrote:
>> On Sat, Aug 06, 2011 at 11:17:18PM +0200, Rafael J. Wysocki wrote:
>>> From: Rafael J. Wysocki <rjw@sisk.pl>
>>>
>>> Freeze all filesystems during the freezing of tasks by calling
>>> freeze_bdev() for each of them and thaw them during the thawing
>>> of tasks with the help of thaw_bdev().
>>>
>>> This is needed by hibernation, because some filesystems (e.g. XFS)
>>> deadlock with the preallocation of memory used by it if the memory
>>> pressure caused by it is too heavy.
>>>
>>> The additional benefit of this change is that, if something goes
>>> wrong after filesystems have been frozen, they will stay in a
>>> consistent state and journal replays won't be necessary (e.g. after
>>> a failing suspend or resume). In particular, this should help to
>>> solve a long-standing issue that in some cases during resume from
>>> hibernation the boot loader causes the journal to be replied for the
>>> filesystem containing the kernel image and initrd causing it to
>>> become inconsistent with the information stored in the hibernation
>>> image.
>>>
>>> This change is based on earlier work by Nigel Cunningham.
>>>
>>> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
>>> ---
>
> Below is an alternative fix, the changelog pretty much explains the idea.
>
> I've tested it on Toshiba Portege R500, but I don't have an XFS partition
> to verify that it really helps, so I'd appreciate it if someone able to
> reproduce the original issue could test it and report back.
>
> Thanks,
> Rafael
>
> ---
> From: Rafael J. Wysocki <rjw@sisk.pl>
> Subject: PM / Hibernate: Freeze kernel threads after preallocating memory
>
> There is a problem with the current ordering of hibernate code which
> leads to deadlocks in some filesystems' memory shrinkers. Namely,
> some filesystems use freezable kernel threads that are inactive when
> the hibernate memory preallocation is carried out. Those same
> filesystems use memory shrinkers that may be triggered by the
> hibernate memory preallocation. If those memory shrinkers wait for
> the frozen kernel threads, the hibernate process deadlocks (this
> happens with XFS, for one example).
>
> Apparently, it is not technically viable to redesign the filesystems
> in question to avoid the situation described above, so the only
> possible solution of this issue is to defer the freezing of kernel
> threads until the hibernate memory preallocation is done, which is
> implemented by this change.
>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
> include/linux/freezer.h | 4 +++-
> kernel/power/hibernate.c | 12 ++++++++----
> kernel/power/power.h | 3 ++-
> kernel/power/process.c | 30 ++++++++++++++++++++----------
> 4 files changed, 33 insertions(+), 16 deletions(-)
>
> Index: linux/kernel/power/process.c
> ===================================================================
> --- linux.orig/kernel/power/process.c
> +++ linux/kernel/power/process.c
> @@ -135,7 +135,7 @@ static int try_to_freeze_tasks(bool sig_
> }
>
> /**
> - * freeze_processes - tell processes to enter the refrigerator
> + * freeze_processes - Signal user space processes to enter the refrigerator.
> */
> int freeze_processes(void)
> {
> @@ -143,20 +143,30 @@ int freeze_processes(void)
>
> printk("Freezing user space processes ... ");
> error = try_to_freeze_tasks(true);
> - if (error)
> - goto Exit;
> - printk("done.\n");
> + if (!error) {
> + printk("done.");
> + oom_killer_disable();
> + }
> + printk("\n");
> + BUG_ON(in_atomic());
> +
> + return error;
> +}
> +
> +/**
> + * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
> + */
> +int freeze_kernel_threads(void)
> +{
> + int error;
>
> printk("Freezing remaining freezable tasks ... ");
> error = try_to_freeze_tasks(false);
> - if (error)
> - goto Exit;
> - printk("done.");
> + if (!error)
> + printk("done.");
>
> - oom_killer_disable();
> - Exit:
> - BUG_ON(in_atomic());
> printk("\n");
> + BUG_ON(in_atomic());
>
> return error;
> }
> Index: linux/include/linux/freezer.h
> ===================================================================
> --- linux.orig/include/linux/freezer.h
> +++ linux/include/linux/freezer.h
> @@ -49,6 +49,7 @@ extern int thaw_process(struct task_stru
>
> extern void refrigerator(void);
> extern int freeze_processes(void);
> +extern int freeze_kernel_threads(void);
> extern void thaw_processes(void);
>
> static inline int try_to_freeze(void)
> @@ -171,7 +172,8 @@ static inline void clear_freeze_flag(str
> static inline int thaw_process(struct task_struct *p) { return 1; }
>
> static inline void refrigerator(void) {}
> -static inline int freeze_processes(void) { BUG(); return 0; }
> +static inline int freeze_processes(void) { return -ENOSYS; }
> +static inline int freeze_kernel_threads(void) { return -ENOSYS; }
> static inline void thaw_processes(void) {}
>
> static inline int try_to_freeze(void) { return 0; }
> Index: linux/kernel/power/power.h
> ===================================================================
> --- linux.orig/kernel/power/power.h
> +++ linux/kernel/power/power.h
> @@ -228,7 +228,8 @@ extern int pm_test_level;
> #ifdef CONFIG_SUSPEND_FREEZER
> static inline int suspend_freeze_processes(void)
> {
> - return freeze_processes();
> + int error = freeze_processes();
> + return error ? : freeze_kernel_threads();
> }
>
> static inline void suspend_thaw_processes(void)
> Index: linux/kernel/power/hibernate.c
> ===================================================================
> --- linux.orig/kernel/power/hibernate.c
> +++ linux/kernel/power/hibernate.c
> @@ -334,13 +334,17 @@ int hibernation_snapshot(int platform_mo
> if (error)
> goto Close;
>
> - error = dpm_prepare(PMSG_FREEZE);
> - if (error)
> - goto Complete_devices;
> -
> /* Preallocate image memory before shutting down devices. */
> error = hibernate_preallocate_memory();
> if (error)
> + goto Close;
> +
> + error = freeze_kernel_threads();
> + if (error)
> + goto Close;
> +
> + error = dpm_prepare(PMSG_FREEZE);
> + if (error)
> goto Complete_devices;
>
> suspend_console();
[unhandled content-type:application/octet-stream]
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