Date:   Sat, 9 Feb 2019 19:45:52 +0100
From:   Sander Eikelenboom <linux@...elenboom.it>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>
Subject: Re: Linux 5.0 regression: BUG: unable to handle kernel paging request
 at ffff888023e26778 RIP: e030:move_page_tables+0x7c1/0xae0

On 09/02/2019 09:26, Sander Eikelenboom wrote:
> L.S.,
> 
> 
> While testing a Linux 5.0-rc5-ish kernel (pull of yesterday) with some additional patches for
> already reported other issues i came across the issue below which i haven't seen with 4.20.x
> 
> I haven't got a reproducer so i might be hard to hit it again, 
> system is AMD and this is from the host kernel running under
> the Xen hypervisor might it matter.

> --
> 
> Sander

Hi Boris / Juergen,

The commit causing this is:
2c91bd4a4e2e530582d6fd643ea7b86b27907151 mm: speed up mremap by 20x on large regions

Since it seems there haven't been any other reports about this .. 
could it be this doesn't specifically work well with a Xen PVH dom0 ?

I could do a straight revert and i'm testing it now for a while, so far no issues.

I also attached my .config, probably most important:
	CONFIG_HAVE_MOVE_PMD=y
	CONFIG_ARCH_ENABLE_THP_MIGRATION=y
	CONFIG_ARCH_WANTS_THP_SWAP=y
	CONFIG_THP_SWAP=y
	CONFIG_CGROUP_HUGETLB=y
	CONFIG_ARCH_WANT_HUGE_PMD_SHARE=y
	CONFIG_ARCH_WANT_GENERAL_HUGETLB=y
	CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION=y
	CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y
	CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD=y
	CONFIG_HAVE_ARCH_HUGE_VMAP=y
	CONFIG_TRANSPARENT_HUGEPAGE=y
	CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y
	# CONFIG_TRANSPARENT_HUGEPAGE_MADVISE is not set
	CONFIG_TRANSPARENT_HUGE_PAGECACHE=y
	CONFIG_HUGETLBFS=y
	CONFIG_HUGETLB_PAGE=y

Thanks in advance.

--
Sander


> [17035.016433] BUG: unable to handle kernel paging request at ffff888023e26778
> [17035.025887] #PF error: [PROT] [WRITE]
> [17035.035146] PGD 2a2a067 P4D 2a2a067 PUD 2a2b067 PMD 7fe01067 PTE 8010000023e26065
> [17035.044371] Oops: 0003 [#1] SMP NOPTI
> [17035.053720] CPU: 3 PID: 28310 Comm: apt-get Not tainted 5.0.0-rc5-20190208-thp-net-florian-rtl8169-eric-doflr+ #1
> [17035.063440] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640)  , BIOS V1.8B1 09/13/2010
> [17035.072635] RIP: e030:move_page_tables+0x7c1/0xae0
> [17035.081585] Code: ce 00 48 8b 03 31 ff 48 89 44 24 20 e8 9e 72 e4 ff 66 90 48 89 c6 48 89 df e8 8b 89 e4 ff 66 90 48 8b 44 24 20 b9 0c 00 00 00 <48> 89 45 00 41 f6 46 52 40 0f 85 3f 02 00 00 49 8b 7e 40 45 31 c0
> [17035.100225] RSP: e02b:ffffc90000f2bd40 EFLAGS: 00010282
> [17035.109208] RAX: 0000000475e42067 RBX: ffff888023e267e0 RCX: 000000000000000c
> [17035.118332] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000201
> [17035.127378] RBP: ffff888023e26778 R08: aaaaaaaaaaaaaaaa R09: 000000051c1d9000
> [17035.136310] R10: deadbeefdeadf00d R11: ffff88807fc17000 R12: 00007fc59fa00000
> [17035.145433] R13: ffffea00008f89a8 R14: ffff88801c2286c0 R15: 00007fc59f800000
> [17035.154171] FS:  00007fc5a5591100(0000) GS:ffff88807d4c0000(0000) knlGS:0000000000000000
> [17035.162730] CS:  e030 DS: 0000 ES: 0000 CR0: 0000000080050033
> [17035.171180] CR2: ffff888023e26778 CR3: 000000001c3f6000 CR4: 0000000000000660
> [17035.179545] Call Trace:
> [17035.187736]  move_vma.isra.3+0xd1/0x2d0
> [17035.195837]  __se_sys_mremap+0x3c6/0x5b0
> [17035.203986]  do_syscall_64+0x49/0x100
> [17035.212109]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [17035.219971] RIP: 0033:0x7fc5a453527a
> [17035.227558] Code: 73 01 c3 48 8b 0d 1e fc 2a 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 19 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ee fb 2a 00 f7 d8 64 89 01 48
> [17035.243255] RSP: 002b:00007ffda22d96f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
> [17035.251121] RAX: ffffffffffffffda RBX: 0000557d40923a30 RCX: 00007fc5a453527a
> [17035.258986] RDX: 0000000001a00000 RSI: 0000000001900000 RDI: 00007fc59f7ff000
> [17035.267127] RBP: 0000000001a00000 R08: 0000000000000020 R09: 0000000000000040
> [17035.275259] R10: 0000000000000001 R11: 0000000000000246 R12: 00007fc59f7ff060
> [17035.282681] R13: 00007fc59f7ff000 R14: 0000557d40923a30 R15: 0000557d40829aa0
> [17035.290322] Modules linked in:
> [17035.297875] CR2: ffff888023e26778
> [17035.305405] ---[ end trace 6ff49f09286816b6 ]---
> [17035.313131] RIP: e030:move_page_tables+0x7c1/0xae0
> [17035.320326] Code: ce 00 48 8b 03 31 ff 48 89 44 24 20 e8 9e 72 e4 ff 66 90 48 89 c6 48 89 df e8 8b 89 e4 ff 66 90 48 8b 44 24 20 b9 0c 00 00 00 <48> 89 45 00 41 f6 46 52 40 0f 85 3f 02 00 00 49 8b 7e 40 45 31 c0
> [17035.334851] RSP: e02b:ffffc90000f2bd40 EFLAGS: 00010282
> [17035.341727] RAX: 0000000475e42067 RBX: ffff888023e267e0 RCX: 000000000000000c
> [17035.348838] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000201
> [17035.356000] RBP: ffff888023e26778 R08: aaaaaaaaaaaaaaaa R09: 000000051c1d9000
> [17035.363623] R10: deadbeefdeadf00d R11: ffff88807fc17000 R12: 00007fc59fa00000
> [17035.371454] R13: ffffea00008f89a8 R14: ffff88801c2286c0 R15: 00007fc59f800000
> [17035.378958] FS:  00007fc5a5591100(0000) GS:ffff88807d4c0000(0000) knlGS:0000000000000000
> [17035.386585] CS:  e030 DS: 0000 ES: 0000 CR0: 0000000080050033
> [17035.393797] CR2: ffff888023e26778 CR3: 000000001c3f6000 CR4: 0000000000000660
> 
> 
> 


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