https://bugzilla.kernel.org/show_bug.cgi?id=29402 Lukas Czerner <lczerner@xxxxxxxxxx> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |lczerner@xxxxxxxxxx --- Comment #6 from Lukas Czerner <lczerner@xxxxxxxxxx> 2011-02-22 13:43:24 --- Hi Eric, it might be just a shot in the dark, but would you be willing to try out this patch ? Unfortunately I do not currently have a machine to reproduce the problem. I *think* that the problem is in the block layer (bio_batch_end_io() and blkdev_issue_zeroout() to be specific) and since lazy init is using that to do the zeroing we can not hit it with lazy init turned off. Now, the problem I see is that when we are going to wait_for_completion() in blkdev_issue_discard() we check if the bb.done equals issued (number of issued bios). If it equals, we can skip the wait_for_completion() and jump out of the function since there is nothing to wait for. However, there is a ordering problem because bio_batch_end_io() is calling atomic_inc(&bb->done) before complete(), hence it might seem to blkdev_issue_zeroout() that all bios has been completed and exit. At this point when bio_batch_end_io() is going to call complete(bb->wait) bb does not longer exist since it was declared locally in blkdev_issue_zeroout() ==> panic while trying to acquire wait.lock! (thread 1) (thread 2) bio_batch_end_io() blkdev_issue_zeroout() if(bb) { ... if (bb->end_io) ... bb->end_io(bio, err); ... atomic_inc(&bb->done); ... ... while (issued != atomic_read(&bb.done)) ... (let issued == bb.done) ... (do the rest of the function) ... return ret; complete(bb->wait); ^^^^^^^^ Panic in complete() while trying to acquire spinlock. I hope it is not complete nonsense :).Please let me know whether the patch helps. Thanks! -Lukas -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
