I was able to make one bcache ok, but when trying to make a 2nd one where I only have a backing device, I'm getting repeated page allocation failures. Just to be clear, this is what I want to do: every new HD backed device will have bcache on top even if I don't have a cache device for it, so that I can add bcache later. Is it something reasonable to do? Setup partitions as bcache backing devices without a cache device for them? So right now, I'm trying to do md5 - bcache - dmcrypt - btrfs So I did make-bcache -B /dev/md5 echo /dev/md5 > /sys/fs/bcache/register and it fails: bash: page allocation failure: order:4, mode:0x2040d0 CPU: 2 PID: 28043 Comm: bash Not tainted 4.3.3-amd64-i915-volpreempt-20150421 #2 Hardware name: System manufacturer System Product Name/P8H67-M PRO, BIOS 3904 04/27/2013 0000000000000000 ffff88006f65ba78 ffffffff8134150e 0000000000000001 ffff88006f65bb10 ffffffff8111f6ce ffff88021f5f4e38 00000004002040d0 0000000400000040 0000000000000286 0000000000000004 0000000000000040 Call Trace: [<ffffffff8134150e>] dump_stack+0x44/0x55 [<ffffffff8111f6ce>] warn_alloc_failed+0x111/0x129 [<ffffffff811220f8>] __alloc_pages_nodemask+0x6ae/0x70d [<ffffffff8115fb98>] kmem_getpages+0x6a/0x162 [<ffffffff8115fd89>] fallback_alloc+0xf9/0x193 [<ffffffff8115ff46>] ____cache_alloc_node+0x123/0x130 [<ffffffff81160f1e>] __kmalloc+0xf8/0x175 [<ffffffffc057e141>] ? kzalloc.constprop.22+0xe/0x10 [bcache] [<ffffffffc057e141>] kzalloc.constprop.22+0xe/0x10 [bcache] [<ffffffffc0580986>] register_bcache+0x61b/0x1452 [bcache] [<ffffffff81342ce0>] kobj_attr_store+0x10/0x1a [<ffffffff811d9677>] sysfs_kf_write+0x39/0x3b [<ffffffff811d8f79>] kernfs_fop_write+0xed/0x130 [<ffffffff81177a05>] __vfs_write+0x26/0xa5 [<ffffffff816c0fdd>] ? _raw_spin_lock+0xe/0x10 [<ffffffff81179277>] ? fput+0x16/0x88 [<ffffffff812cd113>] ? security_file_permission+0x3b/0x42 [<ffffffff8108e79b>] ? percpu_down_read+0x14/0x46 [<ffffffff81179ba7>] ? __sb_start_write+0x25/0x3c [<ffffffff81178067>] vfs_write+0xa2/0xe6 [<ffffffff81178835>] SyS_write+0x4d/0x78 [<ffffffff816c3962>] sysenter_dispatch+0xf/0x29 Mem-Info: active_anon:412014 inactive_anon:222645 isolated_anon:0 active_file:461209 inactive_file:499016 isolated_file:0 unevictable:1166 dirty:28999 writeback:712 unstable:0 slab_reclaimable:69514 slab_unreclaimable:47678 mapped:420280 shmem:410182 pagetables:5369 bounce:0 free:131404 free_pcp:1088 free_cma:0 Node 0 DMA free:15888kB min:20kB low:24kB high:28kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15976kB managed:15892kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:4kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes lowmem_reserve[]: 0 3203 7674 7674 Node 0 DMA32 free:462160kB min:4644kB low:5804kB high:6964kB active_anon:443844kB inactive_anon:470452kB active_file:755044kB inactive_file:897988kB unevictable:1488kB isolated(anon):0kB isolated(file):0kB present:3362068kB managed:3283400kB mlocked:1488kB dirty:21656kB writeback:2912kB mapped:703428kB shmem:665604kB slab_reclaimable:71416kB slab_unreclaimable:69108kB kernel_stack:7056kB pagetables:6732kB unstable:0kB bounce:0kB free_pcp:3008kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no lowmem_reserve[]: 0 0 4471 4471 Node 0 Normal free:26576kB min:6480kB low:8100kB high:9720kB active_anon:1199644kB inactive_anon:420120kB active_file:1091280kB inactive_file:1101072kB unevictable:3176kB isolated(anon):0kB isolated(file):0kB present:4708352kB managed:4578508kB mlocked:3176kB dirty:78692kB writeback:8900kB mapped:977740kB shmem:975112kB slab_reclaimable:206628kB slab_unreclaimable:124308kB kernel_stack:5120kB pagetables:14888kB unstable:0kB bounce:0kB free_pcp:3364kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no lowmem_reserve[]: 0 0 0 0 Node 0 DMA: 0*4kB 0*8kB 1*16kB (U) 0*32kB 2*64kB (U) 1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15888kB Node 0 DMA32: 79732*4kB (UEM) 17590*8kB (UEM) 151*16kB (UM) 1*32kB (U) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 462096kB Node 0 Normal: 4435*4kB (UEM) 5*8kB (UE) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 17780kB Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB 1387415 total pagecache pages 11051 pages in swap cache Swap cache stats: add 4480800, delete 4469749, find 1201429612/1202240702 Free swap = 14096744kB Total swap = 15616764kB 2021599 pages RAM 0 pages HighMem/MovableOnly 52149 pages reserved 4096 pages cma reserved 0 pages hwpoisoned bcache: register_bcache() error opening /dev/md5: (null) Any idea what's going on? gargamel:~# free total used free shared buffers cached Mem: 7877800 6065272 1812528 0 224 4193616 -/+ buffers/cache: 1871432 6006368 Swap: 15616764 1519056 14097708 gargamel:~# cat /proc/meminfo MemTotal: 7877800 kB MemFree: 1799936 kB MemAvailable: 4602768 kB Buffers: 224 kB Cached: 4208328 kB SwapCached: 44472 kB Active: 3595380 kB Inactive: 1508064 kB Active(anon): 1647420 kB Inactive(anon): 891972 kB Active(file): 1947960 kB Inactive(file): 616092 kB Unevictable: 4664 kB Mlocked: 4664 kB SwapTotal: 15616764 kB SwapFree: 14097712 kB Dirty: 104932 kB Writeback: 0 kB AnonPages: 876480 kB Mapped: 1679836 kB Shmem: 1640716 kB Slab: 469492 kB SReclaimable: 280564 kB SUnreclaim: 188928 kB KernelStack: 12288 kB PageTables: 21264 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 19555664 kB Committed_AS: 7995116 kB VmallocTotal: 34359738367 kB VmallocUsed: 409412 kB VmallocChunk: 34358947836 kB HardwareCorrupted: 0 kB AnonHugePages: 0 kB CmaTotal: 16384 kB CmaFree: 232 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 740628 kB DirectMap2M: 7346176 kB Thanks, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ | PGP 1024R/763BE901 -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html