On Wed, Jul 14, 2021 at 12:36 PM Joao Martins <joao.m.martins@xxxxxxxxxx> wrote: > > Use the newly added compound pagemap facility which maps the assigned dax > ranges as compound pages at a page size of @align. Currently, this means, > that region/namespace bootstrap would take considerably less, given that > you would initialize considerably less pages. > > On setups with 128G NVDIMMs the initialization with DRAM stored struct > pages improves from ~268-358 ms to ~78-100 ms with 2M pages, and to less > than a 1msec with 1G pages. > > dax devices are created with a fixed @align (huge page size) which is > enforced through as well at mmap() of the device. Faults, consequently > happen too at the specified @align specified at the creation, and those > don't change through out dax device lifetime. MCEs poisons a whole dax > huge page, as well as splits occurring at the configured page size. > Hi Joao, With this patch I'm hitting the following with the 'device-dax' test [1]. kernel BUG at include/linux/mm.h:748! invalid opcode: 0000 [#1] SMP NOPTI CPU: 29 PID: 1509 Comm: device-dax Tainted: G W OE 5.14.0-rc1+ #720 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:memunmap_pages+0x2f5/0x390 Code: 00 00 00 31 d2 48 8d 70 01 48 29 fe 48 c1 ef 0c 48 c1 ee 0c e8 1c 30 fa ff e9 c5 fe ff ff 48 c7 c6 00 4a 58 87 e8 eb d1 f6 ff <0f> 0b 48 8b 7b 30 31 f6 e8 7e aa 2b 00 e9 2d fd ff ff 48 8d 7b 48 RSP: 0018:ffff9d33c240bbf0 EFLAGS: 00010246 RAX: 000000000000003e RBX: ffff8a44446eb700 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff8a46b3b58af0 RDI: ffff8a46b3b58af0 RBP: 0000000000000000 R08: 0000000000000001 R09: 00000000ffffbfff R10: ffff8a46b32a0000 R11: ffff8a46b32a0000 R12: 0000000000104201 R13: ffff8a44446eb700 R14: 0000000000000004 R15: ffff8a44474954d8 FS: 00007fd048a81fc0(0000) GS:ffff8a46b3b40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000561ee7399000 CR3: 0000000206c70004 CR4: 0000000000170ee0 Call Trace: devres_release_all+0xb8/0x100 __device_release_driver+0x190/0x240 device_release_driver+0x26/0x40 bus_remove_device+0xef/0x160 device_del+0x18c/0x3e0 unregister_dev_dax+0x62/0x90 devres_release_all+0xb8/0x100 __device_release_driver+0x190/0x240 device_driver_detach+0x3e/0xa0 unbind_store+0x113/0x130 [1]: https://github.com/pmem/ndctl/blob/master/test/device-dax.c
