2.6.18 ext3 panic.
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From: Jan Kara on 16 Oct 2006 13:00 > Jan Kara wrote: > > >> This is exactly the solution I proposed earlier (to check > >> buffer_mapped() before calling submit_bh()). > >> But at that time, Jan pointed out that the whole handling is wrong. > > Yes, and it was. However it turned out that there are more problems > > than I thought ;). > > > >> But if this is the only case we need to handle, I am okay with this band > >> aid :) > > I think Eric's patch may be a part of it. But we still need to check whether > > the buffer is not after EOF before submitting it (or better said just > > after we manage to lock the buffer). Because while we are waiting for > > the buffer lock, journal_unmap_buffer() can still come and steal the > > buffer - at least the write-out in journal_dirty_data() definitely needs > > the check if I haven't overlooked something. > > Ok, let me think on that today. My first reaction is that if we have > the bh state lock and pay attention to mapped in journal_dirty_data(), > then any blocks past EOF which have gotten unmapped by > journal_unmap_buffer will be recognized as such (because they are now > unmapped... without needing to check for past EOF...) and we'll be fine. Hmm, yes, you're right. If we do the test in journal_dirty_data() we should not file unmapped buffer into transaction's list and hence we should be safe. Fine. In case we eventually hit the assertion, we can think further ;). > As a datapoint, davej's stresstest (several fsx's and fsstresses) > survived an overnight run on his box, which used to panic in < 2 hrs. > Survived about 6 hours on my box until I intentionally stopped it; my > box had added a write/truncate test in a loop, with a bunch of periodic > syncs as well.... Perfect :). Honza -- Jan Kara <jack(a)suse.cz> SuSE CR Labs - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Eric Sandeen on 16 Oct 2006 13:00
Jan Kara wrote: >>> I think Eric's patch may be a part of it. But we still need to check whether >>> the buffer is not after EOF before submitting it (or better said just >>> after we manage to lock the buffer). Because while we are waiting for >>> the buffer lock, journal_unmap_buffer() can still come and steal the >>> buffer - at least the write-out in journal_dirty_data() definitely needs >>> the check if I haven't overlooked something. >> Ok, let me think on that today. My first reaction is that if we have >> the bh state lock and pay attention to mapped in journal_dirty_data(), >> then any blocks past EOF which have gotten unmapped by >> journal_unmap_buffer will be recognized as such (because they are now >> unmapped... without needing to check for past EOF...) and we'll be fine. > Hmm, yes, you're right. If we do the test in journal_dirty_data() we > should not file unmapped buffer into transaction's list and hence we > should be safe. Fine. In case we eventually hit the assertion, we can > think further ;). Awww no way that can possibly happen right? :) >> As a datapoint, davej's stresstest (several fsx's and fsstresses) >> survived an overnight run on his box, which used to panic in < 2 hrs. >> Survived about 6 hours on my box until I intentionally stopped it; my >> box had added a write/truncate test in a loop, with a bunch of periodic >> syncs as well.... > Perfect :). Ok, thanks Jan! I'll send a patch for -mm as a new thread, this one has gotten buried pretty deep. -Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |