On Tue, Feb 16 2010, Alan Stern wrote: > On Mon, 15 Feb 2010, Rafael J. Wysocki wrote: > > > On Monday 15 February 2010, Maxim Levitsky wrote: > > > On Sat, 2010-02-13 at 15:29 +0200, Maxim Levitsky wrote: > > > > I noticed that currently calling del_gendisk leads to sure deadlock if > > > > attemped from .suspend or .resume functions. > > > > Well, it shouldn't be called from there, then. > > Even if drivers avoid calling it from within suspend methods, they have > to be able to call it from within resume methods. After all, the > resume method may find that the disk's device has vanished. del_gendisk() needs process context at least, since it'll sleep (not just for sync/invalidate, but other parts of the destruction as well). > > > > Something like that: > > > > > > > > [<ffffffff8106620a>] ? prepare_to_wait+0x2a/0x90 > > > > [<ffffffff810790bd>] ? trace_hardirqs_on+0xd/0x10 > > > > [<ffffffff8140db12>] ? _raw_spin_unlock_irqrestore+0x42/0x80 > > > > [<ffffffff8112a390>] ? bdi_sched_wait+0x0/0x20 > > > > [<ffffffff8112a39e>] bdi_sched_wait+0xe/0x20 > > > > [<ffffffff8140af6f>] __wait_on_bit+0x5f/0x90 > > > > [<ffffffff8112a390>] ? bdi_sched_wait+0x0/0x20 > > > > [<ffffffff8140b018>] out_of_line_wait_on_bit+0x78/0x90 > > > > [<ffffffff81065fd0>] ? wake_bit_function+0x0/0x40 > > > > [<ffffffff8112a2d3>] ? bdi_queue_work+0xa3/0xe0 > > > > [<ffffffff8112a37f>] bdi_sync_writeback+0x6f/0x80 > > > > [<ffffffff8112a3d2>] sync_inodes_sb+0x22/0x120 > > > > [<ffffffff8112f1d2>] __sync_filesystem+0x82/0x90 > > > > [<ffffffff8112f3db>] sync_filesystem+0x4b/0x70 > > > > [<ffffffff811391de>] fsync_bdev+0x2e/0x60 > > > > [<ffffffff812226be>] invalidate_partition+0x2e/0x50 > > > > [<ffffffff8116b92f>] del_gendisk+0x3f/0x140 > > > > [<ffffffffa00c0233>] mmc_blk_remove+0x33/0x60 [mmc_block] > > > > [<ffffffff81338977>] mmc_bus_remove+0x17/0x20 > > > > [<ffffffff812ce746>] __device_release_driver+0x66/0xc0 > > > > [<ffffffff812ce89d>] device_release_driver+0x2d/0x40 > > > > [<ffffffff812cd9b5>] bus_remove_device+0xb5/0x120 > > > > [<ffffffff812cb46f>] device_del+0x12f/0x1a0 > > > > [<ffffffff81338a5b>] mmc_remove_card+0x5b/0x90 > > > > [<ffffffff8133ac27>] mmc_sd_remove+0x27/0x50 > > > > [<ffffffff81337d8c>] mmc_resume_host+0x10c/0x140 > > > > [<ffffffffa00850e9>] sdhci_resume_host+0x69/0xa0 [sdhci] > > > > [<ffffffffa0bdc39e>] sdhci_pci_resume+0x8e/0xb0 [sdhci_pci] > > > > > > > > bdi_queue_work seems to be the problem. > > > > > > > > Some device drivers need to remove their cards logically in .suspend, > > > > because the card is removable, and can be changed while system is > > > > suspended. > > > > I don't know how to resolve this right now. > > This is a matter for Jens. Is the bdi writeback task freezable? If it > is, should it be made unfreezable? I'm not a big expect on what tasks should be freezable or not. As it stands, the writeback tasks will attempt to freeze and thaw with the system. I guess that screws the sync from resume call, since it's not running and the sync will wait for it to retrieve and finish that work item. To the suspend experts - can we safely mark the writeback tasks as non-freezable? -- Jens Axboe _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
