Re: [PATCH v2 1/3] mm,fs,dax: Change ->pmd_fault to ->huge_fault

From: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: Dave Jiang <dave.jiang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: mawilcox-0li6OtcxBFHby3iVrkZq2A@public.gmane.org,
	linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org,
	dave.hansen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org,
	linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	kirill.shutemov-VuQAYsv1563Yd54FQh9/CA@public.gmane.org,
	jack-IBi9RG/b67k@public.gmane.org,
	akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
	linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	vbabka-AlSwsSmVLrQ@public.gmane.org
Subject: Re: [PATCH v2 1/3] mm,fs,dax: Change ->pmd_fault to ->huge_fault
Date: Mon, 30 Jan 2017 16:43:21 -0700	[thread overview]
Message-ID: <20170130234321.GA26702@linux.intel.com> (raw)
In-Reply-To: <148545058784.17912.6353162518188733642.stgit-Cxk7aZI4ujnJARH06PadV2t3HXsI98Cx0E9HWUfgJXw@public.gmane.org>

On Thu, Jan 26, 2017 at 10:09:47AM -0700, Dave Jiang wrote:
> In preparation for adding the ability to handle PUD pages, convert
> ->pmd_fault to ->huge_fault.  The vm_fault structure is extended to
> include a union of the different page table pointers that may be needed,
> and three flag bits are reserved to indicate which type of pointer is in
> the union.
> 
> [DJ: Forward ported to 4.10-rc]
> 
> Signed-off-by: Matthew Wilcox <mawilcox-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>
> Signed-off-by: Dave Jiang <dave.jiang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

Hey Dave,

Running xfstests generic/030 with XFS + DAX gives me the following kernel BUG,
which I bisected to this commit:

[  370.086205] ------------[ cut here ]------------
[  370.087182] kernel BUG at arch/x86/mm/fault.c:1038!
[  370.088336] invalid opcode: 0000 [#3] PREEMPT SMP
[  370.089073] Modules linked in: dax_pmem nd_pmem dax nd_btt nd_e820 libnvdimm
[  370.090212] CPU: 0 PID: 12415 Comm: xfs_io Tainted: G      D         4.10.0-rc5-mm1-00202-g7e90fc0 #10
[  370.091648] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.1-1.fc24 04/01/2014
[  370.092946] task: ffff8800ac4f8000 task.stack: ffffc9001148c000
[  370.093769] RIP: 0010:mm_fault_error+0x15e/0x190
[  370.094410] RSP: 0000:ffffc9001148fe60 EFLAGS: 00010246
[  370.095135] RAX: 0000000000000000 RBX: 0000000000000006 RCX: ffff8800ac4f8000
[  370.096107] RDX: 00007f111c8e6400 RSI: 0000000000000006 RDI: ffffc9001148ff58
[  370.097087] RBP: ffffc9001148fe88 R08: 0000000000000000 R09: ffff880510bd3300
[  370.098072] R10: ffff8800ac4f8000 R11: 0000000000000000 R12: 00007f111c8e6400
[  370.099057] R13: 00007f111c8e6400 R14: ffff880510bd3300 R15: 0000000000000055
[  370.100135] FS:  00007f111d95e700(0000) GS:ffff880514800000(0000) knlGS:0000000000000000
[  370.101238] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  370.102021] CR2: 00007f111c8e6400 CR3: 00000000add00000 CR4: 00000000001406f0
[  370.103189] Call Trace:
[  370.103537]  __do_page_fault+0x54e/0x590
[  370.104090]  trace_do_page_fault+0x58/0x2c0
[  370.104675]  do_async_page_fault+0x2c/0x90
[  370.105342]  async_page_fault+0x28/0x30
[  370.106044] RIP: 0033:0x405e9a
[  370.106470] RSP: 002b:00007fffb7f30590 EFLAGS: 00010287
[  370.107185] RAX: 00000000004e6400 RBX: 0000000000000057 RCX: 00000000004e7000
[  370.108155] RDX: 00007f111c400000 RSI: 00000000004e7000 RDI: 0000000001c35080
[  370.109157] RBP: 00000000004e6400 R08: 0000000000000014 R09: 1999999999999999
[  370.110158] R10: 00007f111d2dc200 R11: 0000000000000000 R12: 0000000001c32fc0
[  370.111165] R13: 0000000000000000 R14: 0000000000000c00 R15: 0000000000000005
[  370.112171] Code: 07 00 00 00 e8 a4 ee ff ff e9 11 ff ff ff 4c 89 ea 48 89 de 45 31 c0 31 c9 e8 8f f7 ff ff 48 83 c4 08 5b 41 5c 41 5d 41 5e 5d c3 <0f> 0b 41 8b 94 24 80 04 00 00 49 8d b4 24 b0 06 00 00 4c 89 e9 
[  370.114823] RIP: mm_fault_error+0x15e/0x190 RSP: ffffc9001148fe60
[  370.115722] ---[ end trace 2ce10d930638254d ]---

Can you let me know if you can reproduce this?

Thanks,
- Ross