On Tue, Jan 31, 2017 at 02:33:47PM -0700, Dave Jiang wrote: > Ross reported that: > Running xfstests generic/030 with XFS + DAX gives me the following kernel BUG, > which I bisected to this commit: mm,fs,dax: Change ->pmd_fault to ->huge_fault > > [ 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 ]--- > > It appears that there are 2 issues. First, the size bits used for vm_fault > needs to be shifted over. Otherwise, FAULT_FLAG_SIZE_PMD is clobbering > FAULT_FLAG_INSTRUCTION. Second issue, after create_huge_pmd() is being > called and is falling back to the pte fault handler, the FAULT_FLAG_SIZE_PMD > flag remains and that causes the dax fault handler to go towards the pmd > fault handler instead of the pte fault handler. Fixes are made for the pud > and pmd fall through paths. > > Reported-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> Yep, this seems to solve the issue for me. Thanks! Tested-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
