On Monday 02 March 2015 17:21:26 Jon Masters wrote: > On 03/02/2015 05:50 AM, Catalin Marinas wrote: > > On Mon, Mar 02, 2015 at 12:58:36AM -0500, Jon Masters wrote: > > >> Test kernels running with an explicit DSB in all PTE update cases now > >> running overnight. Just in case. > > ...and stay up after 19 hours. But that's just timing I'm sure. > > > It could be hiding some other problems. > > I checked my GDB macros and they were correct BUT my debugger went out > to lunch soon after that dump so I suspect it was just garbage > > Instead, for my immediate issue, I have a much more likely suspect. For > anyone interested in the followup, you should know that hardware page > table walkers generally do respond well when you feed them Makefiles: > > 0x43e81c0000: 20230a23 656b614d 656c6966 726f6620 : #.# Makefile for > 0x43e81c0010: 65687420 462d4920 6563726f 69726420 : the I-Force dri > 0x43e81c0020: 0a726576 20230a23 4a207942 6e61686f : ver.#.# By Johan > 0x43e81c0030: 6544206e 7875656e 6f6a3c20 6e6e6168 : n Deneux <johann > 0x43e81c0040: 6e65642e 40787565 69616d67 6f632e6c : .deneux@xxxxxxxx > 0x43e81c0050: 230a3e6d 626f0a0a 28242d6a 464e4f43 : m>.#..obj-$(CONF > 0x43e81c0060: 4a5f4749 5453594f 5f4b4349 524f4649 : IG_JOYSTICK_IFOR > 0x43e81c0070: 09294543 69203d2b 63726f66 0a6f2e65 : CE).+= iforce.o. > 0x43e81c0080: 6f66690a 2d656372 3d3a2079 6f666920 : .iforce-y := ifo > 0x43e81c0090: 2d656372 6f2e6666 6f666920 2d656372 : rce-ff.o iforce- > 0x43e81c00a0: 6e69616d 69206f2e 63726f66 61702d65 : main.o iforce-pa > 0x43e81c00b0: 74656b63 0a6f2e73 726f6669 242d6563 : ckets.o.iforce-$ > 0x43e81c00c0: 4e4f4328 5f474946 53594f4a 4b434954 : (CONFIG_JOYSTICK > 0x43e81c00d0: 4f46495f 5f454352 29323332 203d2b09 : _IFORCE_232).+= > 0x43e81c00e0: 726f6669 732d6563 6f697265 690a6f2e : iforce-serio.o.i > 0x43e81c00f0: 63726f66 28242d65 464e4f43 4a5f4749 : force-$(CONFIG_J > 0x43e81c0100: 5453594f 5f4b4349 524f4649 555f4543 : OYSTICK_IFORCE_U > 0x43e81c0110: 09294253 69203d2b 63726f66 73752d65 : SB).+= iforce-us > 0x43e81c0120: 0a6f2e62 00000000 00000000 00000000 : b.o............. > > So that explains why things were falling over. It is likely indeed the > bad DMA I have been craving all along. And this time it was so gracious > as to give me the answer in plain ASCII I suspect there will be a > patch for a certain AHCI driver in the not too distant future. I hope this kind of problem becomes easier to debug once we have full iommu support working on arm64. When we had problems like this on PowerPC, using iommu=force to ensure DMA would only be done to pages that are currently mapped to the device was really helpful. Arnd -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>