On Thursday, 22 of November 2007, Jeremy Fitzhardinge wrote:
> It seems that a process blocked in a write to an xfs filesystem due to
> xfs_freeze cannot be frozen by the freezer.
The freezer doesn't handle tasks in TASK_UNINTERRUPTIBLE and I don't know how
to make it handle them without at least partially defeating its purpose.
> I see this if I suspend my laptop while doing something xfs-filesystem
> intensive, like a kernel build. My suspend scripts freeze the XFS
> filesystem (as Dave said I should), which presumably blocks some writer,
> and then the freezer times out and fails to complete.
> Here's part of the process dump the freezer does when it times out:
> cc1 D 00000000 0 18138 18137
> dd5f1e24 00200082 00000002 00000000 ecdeeb00 ecdeec64 c200f280
> 009c09a0 dd5f1e0c dd5f1e0c 0000000f 00000000 00000000 00000000
> c7beb480 dd5f1e88 dd5f1ea8 c0228d97 e8889540 dd5f1e38 c015b75d
> Call Trace:
> [<c0228d97>] xfs_write+0xf4/0x6d9
> [<c0226038>] xfs_file_aio_write+0x53/0x5b
> [<c0171c15>] do_sync_write+0xae/0xec
> [<c0172343>] vfs_write+0xa4/0x120
> [<c01728d7>] sys_write+0x3b/0x60
> [<c0106fae>] sysenter_past_esp+0x6b/0xa1
> I haven't looked at how to fix this yet. I only just worked out why I
> was getting suspend failures.
Well, you can add freezer_do_not_count()/freezer_count() annotations to
xfs_write() (and whatever else is blocked as a result of the XFS being frozen).
Generally, that would be risky without the freezing of XFS, however, because it
might leak us filesystem data to a storage device after creating a hibernation
image which would result in the filesystem corruption after the resume.
Still, if you only suspend to RAM, that should be safe.