Re: Regression in suspend to ram in 2.6.31-rc kernels

[Zdenek Kabelac <zdenek.kabelac@gmail.com>]

2009/9/5 OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>:
> Zdenek Kabelac <zdenek.kabelac@gmail.com> writes:
>
>> 2009/9/4 OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>:
>>> Christoph Hellwig <hch@lst.de> writes:
>>>
>>>> Note that when you rever this patch on a current kernel you do actually
>>>> get different behvaviour than when going back to before this commit.
>>>>
>>>> In 2.6.30 we called ->write_super in the various sync functions and
>>>> then ->sync_fs, in 2.6.31-rc8 you would not call any syncing at all
>>>> anymore.  I think this patch might just be a symptom for a situation
>>>> where the suspend code causes a sync and the mmc driver can't handle
>>>> it anymore.
>>
>> So - here is the console trace from suspend when I've added
>> dump_stack() to the fat_sync_fs()   (and also added debug prints
>> around each call in this function -so its obvious the function is
>> actually left - but then it freezes later somewhere.)
>>
>> It's interesting that 3 calls to sync happens.
>
> It seems
>
>    1) sync() (probabry "sync" command)
>    2) sync as part of suspend sequence
>    3) sync_filesystem() by mmc remove event
>
> I guess the root-cause of the problem would be 3). However, it would not
> be easy to fix, at least, we would need to think about what we want to
> do for it. So, to workaround it for now, I've made this patch.
>
> Can you try whether this patch fixes this problem?
>

So I've tested your patch - it seems to fix the problem in suspend -
the machine sleeps - however after resume the mmc SD card becomes
unusable to the system and appended call trace filled my message log
very quickly:

After reboot the filesystem appeared to be usable again without errors.

Call Trace:
 [<ffffffff81134f6b>] __getblk+0x2cb/0x300
 [<ffffffff813dcb58>] ? _spin_unlock_irqrestore+0x38/0x80
 [<ffffffff81135122>] __breadahead+0x12/0x40
 [<ffffffffa0520cb7>] fat_count_free_clusters+0x307/0x320 [fat]
 [<ffffffff81103a58>] ? check_object+0xd8/0x260
 [<ffffffff8107d83d>] ? trace_hardirqs_on+0xd/0x10
 [<ffffffffa0522d55>] fat_statfs+0xf5/0x110 [fat]
 [<ffffffff8110be5c>] vfs_statfs+0x7c/0xa0
 [<ffffffff8110c0b0>] vfs_statfs_native+0x20/0xb0
 [<ffffffff8110c243>] sys_statfs+0x73/0xb0
 [<ffffffff8122ab2b>] ? __up_write+0xcb/0x120
 [<ffffffff8100c18c>] ? sysret_check+0x27/0x62
 [<ffffffff8109eb8b>] ? audit_syscall_entry+0x28b/0x2b0
 [<ffffffff8107d7ed>] ? trace_hardirqs_on_caller+0x15d/0x1a0
 [<ffffffff813dbf1e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff8100c15b>] system_call_fastpath+0x16/0x1b
getblk(): invalid block size 512 requested
logical block size: 27499

 [<ffffffff81135122>] __breadahead+0x12/0x40
 [<ffffffffa0520cb7>] fat_count_free_clusters+0x307/0x320 [fat]
 [<ffffffff81103a58>] ? check_object+0xd8/0x260
 [<ffffffff8107d83d>] ? trace_hardirqs_on+0xd/0x10
 [<ffffffffa0522d55>] fat_statfs+0xf5/0x110 [fat]
 [<ffffffff8110be5c>] vfs_statfs+0x7c/0xa0
 [<ffffffff8110c0b0>] vfs_statfs_native+0x20/0xb0
 [<ffffffff8110c243>] sys_statfs+0x73/0xb0
 [<ffffffff8122ab2b>] ? __up_write+0xcb/0x120
 [<ffffffff8100c18c>] ? sysret_check+0x27/0x62
 [<ffffffff8109eb8b>] ? audit_syscall_entry+0x28b/0x2b0
 [<ffffffff8107d7ed>] ? trace_hardirqs_on_caller+0x15d/0x1a0
 [<ffffffff813dbf1e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff8100c15b>] system_call_fastpath+0x16/0x1b

Zdenek