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Date: Sun, 6 Mar 2016 19:35:02 -0500 From: Paul Gortmaker <paul.gortmaker@...driver.com> To: Toshi Kani <toshi.kani@....com> CC: Borislav Petkov <bp@...e.de>, Richard Purdie <richard.purdie@...uxfoundation.org>, Toshi Kani <toshi.kani@...com>, Bruce Ashfield <bruce.ashfield@...driver.com>, openembedded-core <openembedded-core@...ts.openembedded.org>, "Hart, Darren" <darren.hart@...el.com>, "saul.wold" <saul.wold@...el.com>, <linux-kernel@...r.kernel.org> Subject: Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled" [Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled"] On 04/03/2016 (Fri 15:12) Toshi Kani wrote: > On Fri, 2016-03-04 at 13:37 -0500, Paul Gortmaker wrote: > > [Re: runtime regression with "x86/mm/pat: Emulate PAT when it is > > disabled"] On 03/03/2016 (Thu 22:02) Toshi Kani wrote: > > > > > On Thu, 2016-03-03 at 15:59 -0500, Paul Gortmaker wrote: > : > > > > > > > > The stand alone reproducer is here; launched in 00-runme: > > > > > > > > http://openlinux.wrs.com/pat-splat/reproducer.tar.bz2 > > > > > > > > It is nothing fancy, just a generic yocto build of "sato" (gfx > > > > enabled rootfs). When it "works" it boots to a UI touchscreen > > > > interface. When > > > > it fails, you get a black screen with a blinking cursor (as seen in > > > > "vncviewer localhost:0"). > > > > > > Thanks for tracking down, and packaging the reproducer. I simply > > > untar'd and ran 00-runme, but was not able to connect with localhost:0. > > > I am not familiar with qemu, so I have not looked into why, though... > > > > Maybe it was localhost:1 in your case? The qemu should have indicated > > what vncserver sessions it started. Can you paste in the output from > > the 00-runme? I tested the reproducer on a machine that was physically > > distinct from the build, and that was a generic ubuntu install, but with > > no qemu support installed at all and it worked there. Plus I got Bruce > > to test it worked on his machine, so I'm rather surprised it did not > > work for you. > > I am not really sure what I am doing is correct. > > On one window: > # ./00-runme > Warning: vlan 0 is not connected to host network > VNC server running on '::1:5900' Ah, it seems for some reason your system confuses qemu from using the "normal" IPv4 default. Try editing ./00-runme and add an explicit vnc option "-vnc 127.0.0.1:5" in front of "-show-cursor" and then: > > And another window on the same system: > # vncviewer localhost:1 ...connect to localhost:5 here. I chose 5 just to not bump into anything your system might have on :0 or :1 already. > > TigerVNC Viewer 64-bit v1.6.0 > Built on: 2016-01-04 15:09 > Copyright (C) 1999-2015 TigerVNC Team and many others (see README.txt) > See http://www.tigervnc.org for information on TigerVNC. > Can't open display: > [snip analysis, leaving that for Richard to comment on.] > > > > Also, can you send me a whole dmesg output? I'd like to check how PAT > > > is initialized. > > > > I'll send the full file off list vs. spamming everyone with it. I'm open > > to booting the pre-fail commit with PAT specific bootargs and the post- > > fail with the same and diffing the two dmesg if there are bootargs you'd > > like me to test. I'd also like to ensure you have a working reproducer > > locally so maybe we should look at how that failed 1st. > > Great. Yes, two dmesg will be really helpful. So I booted both with "debugpat" on the bootline; both being the last working commit [v4.1-rc5-21-g9dac62909451] and then the 1st failing commit [v4.1-rc5-22-g9cd25aac1f44]. I captured the dmesg of each, then stripped the timestamps and diffed them. --- works.txt 2016-03-06 19:13:28.245836555 -0500 +++ fail.txt 2016-03-06 19:13:17.321836308 -0500 @@ -454,15 +454,38 @@ 8021q: 802.1Q VLAN Support v1.8 8021q: adding VLAN 0 to HW filter on device eth0 x86/PAT: Overlap at 0xfd000000-0xfe000000 - x86/PAT: reserve_memtype added [mem 0xfd000000-0xfdffffff], track write-combining, req write-combining, ret write-combining - x86/PAT: Overlap at 0xfe000000-0xfe010000 - x86/PAT: reserve_memtype added [mem 0xfe000000-0xfe00ffff], track uncached-minus, req uncached-minus, ret uncached-minus + x86/PAT: reserve_memtype added [mem 0xfd000000-0xfdffffff], track write-combining, req uncached-minus, ret write-combining x86/PAT: free_memtype request [mem 0xfd000000-0xfdffffff] - x86/PAT: free_memtype request [mem 0xfe000000-0xfe00ffff] + x86/PAT: Xorg:475 map pfn expected mapping type uncached-minus for [mem 0xfd000000-0xfdffffff], got write-combining + ------------[ cut here ]------------ + WARNING: CPU: 0 PID: 475 at /home/paul/poky/build/tmp-glibc/work-shared/qemux86/kernel-source/arch/x86/mm/pat.c:938 untrack_pfn+0x9f/0xb0() + Modules linked in: 8021q parport_pc parport floppy uvesafb + CPU: 0 PID: 475 Comm: Xorg Not tainted 4.1.0-rc5-yocto-standard #1 + Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014 + 00000000 00000000 cdf75db0 c1837711 00000000 cdf75de4 c104f0cb c1a39d10 + 00000000 000001db c1a38f54 000003aa c1049ddf 000003aa c1049ddf 00000000 + c0108840 00000000 cdf75df4 c104f1a2 00000009 00000000 cdf75e18 c1049ddf + Call Trace: + [<c1837711>] dump_stack+0x4b/0x75 + [<c104f0cb>] warn_slowpath_common+0x8b/0xc0 + [<c1049ddf>] ? untrack_pfn+0x9f/0xb0 + [<c1049ddf>] ? untrack_pfn+0x9f/0xb0 + [<c104f1a2>] warn_slowpath_null+0x22/0x30 + [<c1049ddf>] untrack_pfn+0x9f/0xb0 + [<c104b9d3>] ? __kunmap_atomic+0x33/0xc0 + [<c113c07f>] unmap_single_vma+0x49f/0x4b0 + [<c113cdc3>] unmap_vmas+0x43/0x60 + [<c11428ff>] exit_mmap+0x5f/0xf0 + [<c1072d39>] ? get_parent_ip+0x9/0x40 + [<c104cccd>] mmput+0x2d/0xa0 + [<c104dfdd>] copy_process.part.45+0x10dd/0x14a0 + [<c104e541>] do_fork+0xc1/0x390 + [<c104e8d5>] SyS_clone+0x25/0x30 + [<c183ef46>] syscall_call+0x7/0x7 + ---[ end trace dbbf5a6b2dea64ff ]--- x86/PAT: Overlap at 0xfd000000-0xfe000000 - x86/PAT: reserve_memtype added [mem 0xfd000000-0xfdffffff], track write-combining, req write-combining, ret write-combining - x86/PAT: Overlap at 0xfe000000-0xfe010000 - x86/PAT: reserve_memtype added [mem 0xfe000000-0xfe00ffff], track uncached-minus, req uncached-minus, ret uncached-minus + x86/PAT: reserve_memtype added [mem 0xfd000000-0xfdffffff], track write-combining, req uncached-minus, ret write-combining x86/PAT: free_memtype request [mem 0xfd000000-0xfdffffff] + x86/PAT: Xorg:475 map pfn expected mapping type uncached-minus for [mem 0xfd000000-0xfdffffff], got write-combining x86/PAT: free_memtype request [mem 0xfe000000-0xfe00ffff] - hrtimer: interrupt took 5057254 ns + x86/PAT: free_memtype request [mem 0xfd000000-0xfdffffff] One obvious difference is the number of overlaps: ~$cat fail.txt |grep Overlap | wc -l 7 ~$cat works.txt |grep Overlap | wc -l 9 ~$ I'm assuming everyone here is used to reading diffs, but if someone wants the full dmesg files let me know and I'll send them off-list. Paul.
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