Greetings, I got the below dmesg and the first bad commit is commit 20545536cd8ea949c61527b6395ec8c0d2c237b1 Author: Boaz Harrosh Date: Thu Jul 19 15:22:37 2012 +0300 RFC: do_xor_speed Broken on UML do to jiffies Remember that hang I reported a while back on UML. Well I'm at it again, and it still hangs and I found why. I have dprinted jiffies and it never advances during the loop at do_xor_speed. There for it is stuck in an endless loop. I have also dprinted current_kernel_time() and it returns the same constant value as well. Note that it does usually work on UML, only during the modprobe of xor.ko while that test is running. It looks like some lucking is preventing the clock from ticking. However ktime_get_ts does work for me so I changed the code as below, so I can work. See how I put several safety guards, to never get hangs again. And I think my time based approach is more accurate then previous system. UML guys please investigate the jiffies issue? what is xor.ko not doing right? Signed-off-by: Boaz Harrosh [ 0.232004] generic_sse: 6816.333 MB/sec [ 0.233534] xor: using function: prefetch64-sse (9178.666 MB/sec) [ 0.235445] ------------[ cut here ]------------ [ 0.236010] WARNING: CPU: 0 PID: 1 at init/main.c:701 do_one_initcall+0x128/0x138() [ 0.240041] initcall calibrate_xor_blocks+0x0/0x144 returned with preemption imbalance [ 0.242872] Modules linked in: [ 0.244006] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.12.0-rc4-wl-02197-g3d5587e #119 [ 0.246837] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 0.248004] 0000000000000000 ffff88000e1e5e00 ffffffff81a3a6bf ffff88000e1e5e48 [ 0.252003] ffff88000e1e5e38 ffffffff810c53d5 ffffffff81000315 ffffffff8256ff16 [ 0.255243] 0000000000000000 0000000000000000 ffff88000e1e5fd8 ffff88000e1e5e98 [ 0.258537] Call Trace: [ 0.260010] [] dump_stack+0x54/0x74 [ 0.261730] [] warn_slowpath_common+0x7f/0x98 [ 0.263623] [] ? do_one_initcall+0x128/0x138 [ 0.264006] [] ? do_xor_speed+0xe2/0xe2 [ 0.265785] [] warn_slowpath_fmt+0x4c/0x4e [ 0.268007] [] ? free_pages+0x45/0x47 [ 0.269751] [] ? do_xor_speed+0xe2/0xe2 [ 0.272006] [] do_one_initcall+0x128/0x138 [ 0.273843] [] kernel_init_freeable+0x159/0x1da [ 0.276005] [] ? do_early_param+0x88/0x88 [ 0.277835] [] ? rest_init+0xdb/0xdb [ 0.280006] [] kernel_init+0xe/0xdb [ 0.281718] [] ret_from_fork+0x7c/0xb0 [ 0.283485] [] ? rest_init+0xdb/0xdb [ 0.284021] ---[ end trace 3592511960ba24aa ]--- [ 0.285636] atomic64 test passed for x86-64 platform with CX8 and with SSE git bisect start 3d5587ec7222eebd6d2fa2d4b245ef837a8f36fa 15c03dd4859ab16f9212238f29dd315654aa94f6 -- git bisect good bd1bc39506ad6ce236bf932757d6e3a81b3e3d55 # 09:41 20+ 0 Merge 'regmap/topic/core' into devel-hourly-2013101007 git bisect good f0a6d5852cc8b4e9e518c0426580f0589327e438 # 10:56 20+ 0 Merge 'arm-soc/next/dt' into devel-hourly-2013101007 git bisect good 909dc6fa1f1f42dcdae62b07c4d6b894a392e0d7 # 11:36 20+ 0 Merge 'ipsec-next/testing' into devel-hourly-2013101007 git bisect good 7fb1b0615235b3975def59fbffd0f52c71736bd3 # 11:57 20+ 1 Merge 'arm-soc/next/drivers' into devel-hourly-2013101007 git bisect good ac5fb9846698e9dffc430ab38c1aaefe50a51980 # 12:22 20+ 0 Merge remote-tracking branch 'regulator/topic/optional' into regulator-next git bisect good b9729e9f8d82724c98f13dd358c7b08a4d7de3d2 # 13:31 20+ 3 mtd: nand: pxa3xx_nand: Remove redundant of_match_ptr git bisect bad c420082bfcc00a908360edd4bb5826ece1c59ae4 # 14:13 0- 20 Merge 'open-osd/exofs_ioctl' into devel-hourly-2013101007 git bisect good 3f8985b977fbab1bf7ddea03bf311949ebca4afd # 15:03 20+ 0 Merge remote-tracking branch 'regulator/topic/tps6586x' into regulator-next git bisect bad 7425910fffb08f541e4d2819c4ae7900894fc504 # 15:41 0- 1 {OUT-OF-TREE-DEBUG}: Remove the cdb_offset check because of osc-osd bug git bisect bad 71e6bb4b77c4782642b3cb6b4f9369191e08b934 # 15:48 0- 1 pnfs_osd_xdr_srv (private): Add pnfs-objects server side XDR encoding/decoding git bisect bad 20545536cd8ea949c61527b6395ec8c0d2c237b1 # 16:03 0- 16 RFC: do_xor_speed Broken on UML do to jiffies git bisect good 4a9a4b3528afce48d3f4b1c07b988040e78112e2 # 16:22 20+ 0 pnfs: Proper delay for NFS4ERR_RECALLCONFLICT in layout_get_done git bisect good 4a9a4b3528afce48d3f4b1c07b988040e78112e2 # 16:36 60+ 0 pnfs: Proper delay for NFS4ERR_RECALLCONFLICT in layout_get_done git bisect bad 3d5587ec7222eebd6d2fa2d4b245ef837a8f36fa # 16:36 0- 19 Merge 'tip/x86/bsp-hotplug' into devel-hourly-2013101007 git bisect good 0e7a3ed04f0cd4311096d691888f88569310ee6c # 16:57 63+ 0 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip git bisect good a0cf1abc25ac197dd97b857c0f6341066a8cb1cf # 16:57 63+ 0 Add linux-next specific files for 20130927 Thanks, Fengguang