On 11/9/16 10:09, Christoph Hellwig wrote: > Ok, sounds like I'm really the one to blame. I'll see if I can > find a reproducer. Damien, or you using device mapper on that > system? No LVM/md/dm used on boot. Mount is direct to the block device (SSDs with ext4). The devices are simple SSDs, so no polling involved. The hangs suspiciously look like they are either background write or flush. So I was wondering if it is indeed related to FLUSH/FUA as Logan suggested or the background write stuff, rather than the direct-IO optimization & polling. Will try again/bisect to see if I can get more info. Cheers. -- Damien Le Moal, Ph.D. Sr. Manager, System Software Research Group, Western Digital Corporation Damien.LeMoal@xxxxxxx (+81) 0466-98-3593 (ext. 513593) 1 kirihara-cho, Fujisawa, Kanagawa, 252-0888 Japan www.wdc.com, www.hgst.com -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
