On 18 Sep 2011, at 15:01, James Bottomley wrote: > On Sun, 2011-09-18 at 13:39 +0000, Woodhouse, David wrote: >> On Sun, 2011-09-18 at 13:06 +0100, Chris Boot wrote: >>> On 17 Sep 2011, at 20:22, adam radford wrote: >>>> On Sat, Sep 17, 2011 at 7:29 AM, Chris Boot <bootc@xxxxxxxxx> wrote: >>>>> On 17 Sep 2011, at 12:57, Chris Boot wrote: >>>>>> On 17 Sep 2011, at 11:45, Woodhouse, David wrote: >>>>>>> I suppose it's vaguely possible that we're leaking them in such a way >>>>>>> that they remain on the rbtree, perhaps if the deferred unmap is never >>>>>>> actually happening... but I think it's a whole lot more likely that the >>>>>>> PCI driver is just never bothering to unmap the pages it maps. >>>> >>>> If you think 3w-9xxx is not unmapping pages it maps, please re-run with >>>> CONFIG_PCI_DMA_DEBUG=y >>> >>> Adam, >>> >>> I installed a fresh Debian system on a SATA disk connected to the built-in SATA controller, then played with loading/unloading the 3w-9xxx module and doing a few basic things. Without even prodding very much, I got this result: >>> >>> [ 1142.363173] ------------[ cut here ]------------ >>> [ 1142.368507] WARNING: at lib/dma-debug.c:697 dma_debug_device_change+0x172/0x1a6() >>> [ 1142.377162] Hardware name: S1200BTL >>> [ 1142.381193] pci 0000:01:00.0: DMA-API: device driver has pending DMA allocations while released from device [count=37] >>> [ 1142.381194] One of leaked entries details: [device address=0x00000000fff9a000] [size=4096 bytes] [mapped with DMA_TO_DEVICE] [mapped as scather-gather] >> ... >>> [ 1142.381254] Mapped at: >>> [ 1142.381255] [<ffffffff811c35b1>] debug_dma_map_sg+0x3b/0x140 >>> [ 1142.381256] [<ffffffffa00cb0db>] scsi_dma_map+0x9b/0xb7 [scsi_mod] >>> [ 1142.381260] [<ffffffffa012c675>] twa_scsiop_execute_scsi+0x141/0x3a5 [3w_9xxx] >>> [ 1142.381263] [<ffffffffa012ce3b>] twa_scsi_queue+0xd6/0x16a [3w_9xxx] >>> [ 1142.381265] [<ffffffffa00c4620>] scsi_dispatch_cmd+0x192/0x236 [scsi_mod] >> >> Seems like a smoking gun to me, although at first glance I can't see an >> *obvious* leak in the 3w-9xxx code. Adam? > > Hardly ... all it's saying is that twa_exit doesn't wait for pending I/O > to complete, so when you remove the module it tears down in the middle > of an I/O. A bug, yes, but it's not indicative of any sort of leak in > the maps/unmaps. James, I don't think that's the case - I had unmounted all filesystems, deactivated all volume groups, and performed a sync before waiting a few seconds and running rmmod. Next time I'll also 'echo 1 > /sys/block/sdX/device/delete' if that's helpful. Chris -- Chris Boot bootc@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
