Today I am experiencing problems on my laptop running Fedora 22 with a external USB 3 Seagate hard drive. I plugged the drive in and it wouldn't mount, instead showing low_memory errors in dmesg. Rebooting fixed it initially, but when later on I tried plugging in the disk it wouldn't mount again - this the relevant bit of dmesg:usb 4-4: new SuperSpeed USB device number 6 using xhci_hcd[ 2354.749660] usb 4-4: New USB device found, idVendor=0bc2, idProduct=ab24[ 2354.749680] usb 4-4: New USB device strings: Mfr=2, Product=3, SerialNumber=1[ 2354.749684] usb 4-4: Product: BUP Slim BK[ 2354.749686] usb 4-4: Manufacturer: Seagate[ 2354.749688] usb 4-4: SerialNumber: NA7KR1X0[ 2354.752380] scsi host11: uas[ 2354.752387] kworker/0:2: page allocation failure: order:7, mode:0x208c020[ 2354.752390] CPU: 0 PID: 8715 Comm: kworker/0:2 Tainted: P           OE   4.4.4-200.fc22.x86_64 #1[ 2354.752392] Hardware name: LENOVO 62743QG/62743QG, BIOS H1ET84WW(1.22) 11/26/2013[ 2354.752398] Workqueue: usb_hub_wq hub_event[ 2354.752401]  0000000000000286 000000001bd47e87 ffff8801219fb4d0 ffffffff813b515e[ 2354.752404]  000000000208c020 0000000000000000 ffff8801219fb560 ffffffff811b2fea[ 2354.752406]  0000000000000007 000000008179fbae ffff88021e5e8e00 ffffffffffffff80[ 2354.752409] Call Trace:[ 2354.752415]  [<ffffffff813b515e>] dump_stack+0x63/0x85[ 2354.752419]  [<ffffffff811b2fea>] warn_alloc_failed+0xfa/0x160[ 2354.752422]  [<ffffffff811b6ec1>] __alloc_pages_nodemask+0x361/0xbc0[ 2354.752427]  [<ffffffff81202a1c>] alloc_pages_current+0x8c/0x110[ 2354.752430]  [<ffffffff811b51b9>] alloc_kmem_pages+0x19/0x90[ 2354.752434]  [<ffffffff811d2f4e>] kmalloc_order_trace+0x2e/0xe0[ 2354.752438]  [<ffffffff8120e722>] __kmalloc+0x232/0x260[ 2354.752442]  [<ffffffff8138989d>] init_tag_map+0x3d/0xc0[ 2354.752445]  [<ffffffff81389965>] __blk_queue_init_tags+0x45/0x80[ 2354.752448]  [<ffffffff813899b4>] blk_init_tags+0x14/0x20[ 2354.752452]  [<ffffffff81520b40>] scsi_add_host_with_dma+0x80/0x300[ 2354.752457]  [<ffffffffa00c1423>] uas_probe+0x3e3/0x520 [uas][ 2354.752461]  [<ffffffff8158acad>] usb_probe_interface+0x1bd/0x300[ 2354.752465]  [<ffffffff814eeeb2>] driver_probe_device+0x222/0x490[ 2354.752467]  [<ffffffff814ef221>] __device_attach_driver+0x71/0xa0[ 2354.752470]  [<ffffffff814ef1b0>] ? __driver_attach+0x90/0x90[ 2354.752472]  [<ffffffff814eca67>] bus_for_each_drv+0x67/0xb0[ 2354.752474]  [<ffffffff814eeb8c>] __device_attach+0xdc/0x170[ 2354.752477]  [<ffffffff814ef293>] device_initial_probe+0x13/0x20[ 2354.752479]  [<ffffffff814ede42>] bus_probe_device+0x92/0xa0[ 2354.752481]  [<ffffffff814eb9fb>] device_add+0x40b/0x680[ 2354.752484]  [<ffffffff8157a7b9>] ? usb_enable_lpm+0x89/0x90[ 2354.752487]  [<ffffffff81588b71>] usb_set_configuration+0x511/0x8e0[ 2354.752490]  [<ffffffff815934be>] generic_probe+0x2e/0x80[ 2354.752492]  [<ffffffff8158aab2>] usb_probe_device+0x32/0x70[ 2354.752495]  [<ffffffff814eeeb2>] driver_probe_device+0x222/0x490[ 2354.752497]  [<ffffffff814ef221>] __device_attach_driver+0x71/0xa0[ 2354.752499]  [<ffffffff814ef1b0>] ? __driver_attach+0x90/0x90[ 2354.752501]  [<ffffffff814eca67>] bus_for_each_drv+0x67/0xb0[ 2354.752503]  [<ffffffff814eeb8c>] __device_attach+0xdc/0x170[ 2354.752506]  [<ffffffff814ef293>] device_initial_probe+0x13/0x20[ 2354.752508]  [<ffffffff814ede42>] bus_probe_device+0x92/0xa0[ 2354.752509]  [<ffffffff814eb9fb>] device_add+0x40b/0x680[ 2354.752513]  [<ffffffff814c0400>] ? add_device_randomness+0x50/0x140[ 2354.752516]  [<ffffffff8157e047>] usb_new_device+0x277/0x4b0[ 2354.752519]  [<ffffffff8158028d>] hub_event+0x103d/0x1590[ 2354.752524]  [<ffffffff810bc596>] process_one_work+0x156/0x430[ 2354.752527]  [<ffffffff810bc8be>] worker_thread+0x4e/0x450[ 2354.752531]  [<ffffffff8179b955>] ? __schedule+0x3a5/0xa00[ 2354.752533]  [<ffffffff810bc870>] ? process_one_work+0x430/0x430[ 2354.752536]  [<ffffffff810bc870>] ? process_one_work+0x430/0x430[ 2354.752538]  [<ffffffff810c2648>] kthread+0xd8/0xf0[ 2354.752540]  [<ffffffff810c2570>] ? kthread_worker_fn+0x160/0x160[ 2354.752543]  [<ffffffff817a048f>] ret_from_fork+0x3f/0x70[ 2354.752545]  [<ffffffff810c2570>] ? kthread_worker_fn+0x160/0x160[ 2354.752564] Mem-Info:[ 2354.752571] active_anon:316599 inactive_anon:48172 isolated_anon:0                active_file:647763 inactive_file:660760 isolated_file:0                unevictable:0 dirty:3065 writeback:0 unstable:0                slab_reclaimable:99971 slab_unreclaimable:20297                mapped:57919 shmem:49646 pagetables:9709 bounce:0                free:118581 free_pcp:639 free_cma:0[ 2354.752576] Node 0 DMA free:15884kB 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:15984kB managed:15900kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:16kB 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[ 2354.752585] lowmem_reserve[]: 0 3109 7566 7566[ 2354.752602] Node 0 DMA32 free:270468kB min:4540kB low:5672kB high:6808kB active_anon:503680kB inactive_anon:79744kB active_file:1043728kB inactive_file:1125396kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:3266876kB managed:3187136kB mlocked:0kB dirty:4684kB writeback:0kB mapped:96256kB shmem:81308kB slab_reclaimable:97220kB slab_unreclaimable:27128kB kernel_stack:2704kB pagetables:16068kB unstable:0kB bounce:0kB free_pcp:1456kB local_pcp:144kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no[ 2354.752609] lowmem_reserve[]: 0 0 4456 4456[ 2354.752612] Node 0 Normal free:187972kB min:6504kB low:8128kB high:9756kB active_anon:762716kB inactive_anon:112944kB active_file:1547324kB inactive_file:1517644kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:4691968kB managed:4563068kB mlocked:0kB dirty:7576kB writeback:0kB mapped:135420kB shmem:117276kB slab_reclaimable:302664kB slab_unreclaimable:54044kB kernel_stack:5136kB pagetables:22768kB unstable:0kB bounce:0kB free_pcp:1100kB local_pcp:236kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no[ 2354.752616] lowmem_reserve[]: 0 0 0 0[ 2354.752619] Node 0 DMA: 1*4kB (U) 1*8kB (U) 2*16kB (U) 1*32kB (U) 1*64kB (U) 1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15884kB[ 2354.752643] Node 0 DMA32: 6*4kB (UME) 8*8kB (UME) 11101*16kB (UME) 2803*32kB (UME) 46*64kB (ME) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 270344kB[ 2354.752652] Node 0 Normal: 2*4kB (UM) 2*8kB (UM) 8980*16kB (ME) 1326*32kB (UME) 26*64kB (M) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 187800kB[ 2354.752661] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB[ 2354.752663] 1358227 total pagecache pages[ 2354.752664] 0 pages in swap cache[ 2354.752665] Swap cache stats: add 0, delete 0, find 0/0[ 2354.752666] Free swap  = 0kB[ 2354.752674] Total swap = 0kB[ 2354.752675] 1993707 pages RAM[ 2354.752676] 0 pages HighMem/MovableOnly[ 2354.752677] 52181 pages reserved[ 2354.752678] 0 pages cma reserved[ 2354.752679] 0 pages hwpoisoned[ 2354.753318] uas: probe of 4-4:1.0 failed with error -12and also the amount of memory/swap at the time (free -m):              total        used        free      shared  buff/cache   availableMem:           7584        1237         493         196        5852        6029Swap:             0           0           0As it seemed to be because of limited memory, I cleared the memory cache (echo 3 | sudo tee /proc/sys/vm/drop_caches) and tried again, and it worked :). Here is the dmesg:[ 2714.892041] tee (14048): drop_caches: 3[ 2724.745378] usb 4-4: USB disconnect, device number 6[ 2726.561479] usb 4-2: new SuperSpeed USB device number 7 using xhci_hcd[ 2726.573070] usb 4-2: New USB device found, idVendor=0bc2, idProduct=ab24[ 2726.573075] usb 4-2: New USB device strings: Mfr=2, Product=3, SerialNumber=1[ 2726.573077] usb 4-2: Product: BUP Slim BK[ 2726.573079] usb 4-2: Manufacturer: Seagate[ 2726.573081] usb 4-2: SerialNumber: NA7KR1X0[ 2726.575116] scsi host12: uas[ 2726.576138] scsi 12:0:0:0: Direct-Access     Seagate  BUP Slim BK      0302 PQ: 0 ANSI: 6[ 2726.576923] sd 12:0:0:0: Attached scsi generic sg3 type 0[ 2726.576926] sd 12:0:0:0: [sdc] Spinning up disk...[ 2727.577320] ...ready[ 2729.581063] sd 12:0:0:0: [sdc] 3907029167 512-byte logical blocks: (2.00 TB/1.82 TiB)[ 2729.581070] sd 12:0:0:0: [sdc] 2048-byte physical blocks[ 2729.828378] sd 12:0:0:0: [sdc] Write Protect is off[ 2729.828387] sd 12:0:0:0: [sdc] Mode Sense: 4f 00 00 00[ 2729.828631] sd 12:0:0:0: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA[ 2729.835161]  sdc: sdc1 sdc2 sdc3[ 2729.836456] sd 12:0:0:0: [sdc] Attached SCSI diskAnd the free -m:              total        used        free      shared  buff/cache   availableMem:           7584        1785        5186         228         612        5472Swap:             0           0           0This seems odd as I have had the setup for ages and previously have had no issues - the only recent changes I can think of are me filling the drives as I am trying to reinstall another machine:Filesystem      Size  Used Avail Use% Mounted on/dev/sda6        59G   49G  7.2G  88% //dev/sda7        71G   70G  1.2G  99% /media/Music/dev/sda8       112G   97G   16G  87% /media/Storage/dev/sda5       111G   84G   21G  81% /home/dev/sdc1       448G  434G   14G  97% /run/media/wilf/Seagate Backup Plus Drive/dev/sdc2       917G  867G  3.3G 100% /run/media/wilf/Ext1/dev/sdc3       477G  428G   25G  95% /run/media/wilf/Ext2and perhaps the system being updated. So please:Why did this happen (and how can I fix it)?Would having some swap help with issue?Shouldn't memory cache clear itself if needed anyway (linuxatemyram and all that)?
Why can't I mount the disk now with limited memory?
usb;automounting;ram;external hdd