On Mon, 2017-08-28 at 14:26 +0200, Takashi Iwai wrote: > Hi, > > I seem to get a kernel warning when running KVM on Dell desktop with > IvyBridge like below. As you can see, a bad page BUG is triggered > after that, too. The problem is not triggered always, but it happens > occasionally. > > I haven't seen this on 4.13-rc4 at all, and IIRC, it started happening > since rc5. So this might be a regression at rc5. But, as it doesn't > happen always, I can't be 100% sure about it, and it's quite difficult > to bisect (the test case isn't reliable), unfortunately. > > Any hint for further debugging this? Maybe a way to make failure more likely. This is an RT kernel, but trying to build a fat kernel over NFS from a KVM clone of my workstation (full topology, half of ram) didn't survive one build. [ 2583.153312] WARNING: CPU: 7 PID: 9323 at arch/x86/kvm/mmu.c:717 mmu_spte_clear_track_bits+0x82/0x100 [kvm] [ 2583.153899] WARNING: CPU: 7 PID: 9323 at arch/x86/kvm/mmu.c:717 mmu_spte_clear_track_bits+0x82/0x100 [kvm] [ 2583.154016] WARNING: CPU: 7 PID: 9323 at arch/x86/kvm/mmu.c:717 mmu_spte_clear_track_bits+0x82/0x100 [kvm] [ 2583.158810] WARNING: CPU: 7 PID: 9323 at arch/x86/kvm/mmu.c:717 mmu_spte_clear_track_bits+0x82/0x100 [kvm] [ 2768.419797] BUG: Bad page state in process as pfn:048b3 [ 2768.419932] BUG: Bad page state in process as pfn:04983 [ 2775.097980] BUG: Bad page state in process cc1 pfn:04982 [ 2782.487748] BUG: Bad page state in process cc1 pfn:04980 [ 2782.622636] BUG: Bad page state in process cc1 pfn:048b0 [ 2782.622899] BUG: Bad page state in process cc1 pfn:04984 [ 2782.623053] BUG: Bad page state in process cc1 pfn:04986 [ 2782.673705] BUG: Bad page state in process cc1 pfn:048b4 [ 2782.673903] BUG: Bad page state in process cc1 pfn:048b6 [ 2782.674044] BUG: Bad page state in process cc1 pfn:04989 [ 2782.674185] BUG: Bad page state in process cc1 pfn:0498a [ 2784.895701] BUG: Bad page state in process cc1 pfn:04990 [ 2784.895921] BUG: Bad page state in process cc1 pfn:04992 [ 2784.896100] BUG: Bad page state in process cc1 pfn:04994 [ 2784.896255] BUG: Bad page state in process cc1 pfn:04996 [ 2784.905232] BUG: Bad page state in process cc1 pfn:0499c [ 2784.905501] BUG: Bad page state in process cc1 pfn:0499e [ 2785.762044] BUG: Bad page state in process cc1 pfn:040cb [ 2787.052976] BUG: Bad page state in process cc1 pfn:048ca [ 2787.208480] BUG: Bad page state in process kdesu pfn:048a8 [ 2787.208694] BUG: Bad page state in process kdesu pfn:048aa [ 2787.208862] BUG: Bad page state in process kdesu pfn:048ac [ 2787.208957] BUG: Bad page state in process kdesu pfn:048ae [ 2787.211725] BUG: Bad page state in process cc1 pfn:04884 [ 2787.219784] BUG: Bad page state in process kdesu pfn:04888 [ 2787.226212] BUG: Bad page state in process cc1 pfn:049a0 [ 2788.955108] BUG: Bad page state in process cc1 pfn:048e9 [ 2788.959686] BUG: Bad page state in process cc1 pfn:048f1 [ 2788.959882] BUG: Bad page state in process cc1 pfn:048f2 [ 2788.977485] BUG: Bad page state in process cc1 pfn:048fe [ 2789.295335] BUG: Bad page state in process cc1 pfn:04807 [ 2794.661501] BUG: Bad page state in process cc1 pfn:04819 [ 2794.661658] BUG: Bad page state in process cc1 pfn:0481b [ 2794.661747] BUG: Bad page state in process cc1 pfn:0481d [ 2794.680432] BUG: Bad page state in process cc1 pfn:0482a [ 2794.692849] BUG: Bad page state in process cc1 pfn:04834 [ 2794.705438] BUG: Bad page state in process cc1 pfn:0483c [ 2794.784882] BUG: Bad page state in process gcc pfn:0485c [ 2794.785105] BUG: Bad page state in process gcc pfn:0485e [ 2796.541058] BUG: Bad page state in process Xorg pfn:04011 [ 2808.425625] BUG: Bad page state in process Xorg pfn:04a09 [ 3605.187591] BUG: unable to handle kernel paging request at 000000000001bcf4 [ 3605.202446] BUG: sleeping function called from invalid context at ./include/linux/percpu-rwsem.h:33 [ 3605.203322] BUG: stack guard page was hit at ffffc9000e483ff8 (stack is ffffc9000e484000..ffffc9000e487fff) [ 3605.279108] BUG: scheduling while atomic: ld/5485/0x00000002 >
