Hi Ben, On Sat, 16 Jun 2012 00:03:34 +0100 Ben Hutchings <ben@decadent.org.uk> wrote: > > > [113218.445767] xhci_hcd 0000:0f:00.0: WARN: Stalled endpoint > > [113248.733637] xhci_hcd 0000:0f:00.0: WARN: Stalled endpoint > > [113248.734725] xhci_hcd 0000:0f:00.0: WARN: Stalled endpoint > > [113248.775204] xhci_hcd 0000:0f:00.0: WARN: Stalled endpoint > > [113248.809657] xhci_hcd 0000:0f:00.0: WARN: Stalled endpoint > > [113248.841803] xhci_hcd 0000:0f:00.0: WARN: Stalled endpoint > [...] > > All this suggests that the mount attempt is hanging due to problems > with the USB connection. These messages appear well before I run pmount i.e. when I plug the disk in. > Based on a quick look through the UDF functions in the call stack: > > [168534.534210] [<ffffffffa1108c3c>] ? udf_read_tagged+0x29/0x113 [udf] > [168534.534218] [<ffffffffa1107422>] ? udf_check_anchor_block+0x6e/0xf5 [udf] > [168534.534225] [<ffffffffa11075a2>] ? udf_scan_anchors+0xf9/0x158 [udf] > [168534.534233] [<ffffffffa110781c>] ? udf_load_vrs+0x21b/0x2b9 [udf] > [168534.534240] [<ffffffffa11078ba>] ? udf_load_vrs+0x2b9/0x2b9 [udf] > [168534.534247] [<ffffffffa1107a8a>] ? udf_fill_super+0x1d0/0x4d6 [udf] > > it appears that the filesystem code loops over a finite number of > different places where the superblock might be. So I don't think the > filesystem code has got confused by the mis-detected filesystem and > entered an infinite loop. Instead, single block reads are hanging or > taking a very long time to fail. > > If this is reproducible on Linux 3.4 then I think the people to report > this to would be the xhci maintainers. If not then I'll have a look for > fixes between 3.2 and 3.4. OK, this still hangs the same way in 3.4 (linux-image-3.4-trunk-amd64 3.4.1-1~experimental.1). I am also now using nouveau (just to eliminate the binary nvidia driver). The above xhci messages no longer appear. I get the following instead: [50384.875554] xhci_hcd 0000:0f:00.0: ERROR Transfer event TRB DMA ptr not part of current TD [50415.136011] usb 2-1: reset SuperSpeed USB device number 2 using xhci_hcd [50415.154978] xhci_hcd 0000:0f:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88011497fa40 [50415.154987] xhci_hcd 0000:0f:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88011497fa80 but, again, not while running pmount, just while the disk is being initially detected (the last of those messages appeared 18 minutes before I ran pmount without "-t ext4". Before this test, I had mounted the disk (using pmount -t ext4), written a backup to it and then unmounted it again. -- Cheers, Stephen Rothwell sfr@canb.auug.org.au
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