[Bug 778630] New: nbd: some I/O requests never completed or freed
https://bugzilla.novell.com/show_bug.cgi?id=778630 https://bugzilla.novell.com/show_bug.cgi?id=778630#c0 Summary: nbd: some I/O requests never completed or freed Classification: openSUSE Product: openSUSE 11.4 Version: Final Platform: All OS/Version: SLES 11 Status: NEW Severity: Normal Priority: P5 - None Component: Kernel AssignedTo: kernel-maintainers@forge.provo.novell.com ReportedBy: paul.clements@steeleye.com QAContact: qa-bugs@suse.de Found By: --- Blocker: --- Created an attachment (id=504368) --> (http://bugzilla.novell.com/attachment.cgi?id=504368) patch User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.57 Safari/537.1 The attached patch fixes a serious, but uncommon bug in nbd. It is in -mm, and headed for stable and mainline. It affects all kernels 2.6.25+, so affects all SLES 11, SLED 11, openSUSE 11+ kernels. We have tested to ensure that the problem definitely occurs on SLES 11 SP2. The bug occurs when there is heavy I/O going to the nbd device while, at the same time, a failure (server, network) or manual disconnect of the nbd connection occurs. There is a small window between the time that the nbd_thread is stopped and the socket is shutdown where requests can continue to be queued to nbd's internal waiting_queue. When this happens, those requests are never completed or freed. The fix is to clear the waiting_queue on shutdown of the nbd device, in the same way that the nbd request queue (queue_head) is already being cleared. Reproducible: Sometimes Steps to Reproduce: 1. Perform heavy write I/O over nbd. 2. Break the nbd connection (kill nbd-client or nbd-server or pull network cable) 3. cat /sys/block/nbd0/stat and note that the I/O in progress are not at 0, even though the device has been shut down Expected Results: I/O should be completed (with error) and freed patch may need a little adjustment for older kernels (nbd vs. lo variable naming) -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
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Jeff Mahoney
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Yarny Yarny
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