Messages in this thread | | | Date | Thu, 21 Sep 2006 11:38:13 -0700 | From | Zach Brown <> | Subject | Re: [RFC 0/5] dio: clean up completion phase of direct_io_worker() |
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> on EXT2, EXT3 and XFS filesystems. For the EXT2 and EXT3 filesystems the > tests went okay. But I got stack trace on XFS filesystem and the machine > went down.
Fantastic, thanks for running these tests.
> kernel BUG at kernel/workqueue.c:113!
> EIP is at queue_work+0x86/0x90
We were able to set the pending bit but then found that list_empty() failed on the work queue's entry list_head. Let's call this memory corruption of some kind.
> [<c02b43a2>] xfs_finish_ioend+0x20/0x22 > [<c02b5e2f>] xfs_end_io_direct+0x3c/0x68 > [<c018e77a>] dio_complete+0xe3/0xfe > [<c018e82d>] dio_bio_end_aio+0x98/0xb1 > [<c016e889>] bio_endio+0x4e/0x78 > [<c02cdc89>] __end_that_request_first+0xcd/0x416
It was completing an AIO request.
ret = blockdev_direct_IO_own_locking(rw, iocb, inode, iomap.iomap_target->bt_bdev, iov, offset, nr_segs, xfs_get_blocks_direct, xfs_end_io_direct);
if (unlikely(ret <= 0 && iocb->private)) xfs_destroy_ioend(iocb->private);
It looks like xfs_vm_direct_io() is destroying the ioend in the case where direct IO is returning -EIOCBQUEUED. Later the AIO will complete and try to call queue_work on the freed ioend. This wasn't a problem before when blkdev_direct_IO_*() would just return the number of bytes in the op that was in flight. That test should be
if (unlikely(ret != -EIOCBQUEUED && iocb->private))
I'll update the patch set and send it out.
This makes me worry that XFS might have other paths that need to know about the magical -EIOCBQUEUED case which actually means that a AIO DIO is in flight.
Could I coerce some XFS guys into investigating if we might have other problems with trying to bubble -EIOCBQUEUED up from blockdev_direct_IO_own_locking() up through to xfs_file_aio_write()'s caller before calling xfs_end_io_direct()?
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