On Wed, 22 Jun 2011 10:06:15 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > On Wed, 22 Jun 2011 09:10:18 +0900 > KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > > On Tue, 21 Jun 2011 16:51:18 +0200 > > Lutz Vieweg <lvml@xxxxxx> wrote: > > > > - but also at this time, if any other user (who has not exhausted > > > his memory limits) tries to access any file (at least on /tmp/, > > > as e.g. gcc does), even a simple "ls /tmp/", this operation > > > waits forever. (But "iostat" does not indicate any I/O activity.) > > > > > > > Hmm, it means your 'ls' gets some lock and wait for it. Then, what lock > > you wait for ? what w_chan is shown in 'ps -elf' ? > > > > I reproduced. And checked sysrq t. > > At first, some oom killers run. > Second, oom killer stops by some reason. (I think there are a KILLED process in memcg > but it doesn't exit. I'll check memcg' bypass logic.) > > Third, ls /tmp stops. > > Here is sysrq log. > == > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] ls D 0000000000000082 5448 22307 2799 0x10000000 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] ffff880623a7bb08 0000000000000086 ffff88033fffcc08 ffff88033fffbe70 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] ffff8805fa70c530 0000000000012880 ffff880623a7bfd8 ffff880623a7a010 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] ffff880623a7bfd8 0000000000012880 ffff8805f9c30000 ffff8805fa70c530 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] Call Trace: > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff810ee900>] ? sleep_on_page+0x20/0x20 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff8154f40c>] io_schedule+0x8c/0xd0 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff810ee90e>] sleep_on_page_killable+0xe/0x40 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff8154fddf>] __wait_on_bit+0x5f/0x90 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff810eeab5>] wait_on_page_bit_killable+0x75/0x80 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff810791f0>] ? autoremove_wake_function+0x40/0x40 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff810eec35>] __lock_page_or_retry+0x95/0xc0 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff810efe7f>] filemap_fault+0x2df/0x4b0 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff81115685>] __do_fault+0x55/0x530 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff81119150>] ? unmap_region+0x110/0x140 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff81115c57>] handle_pte_fault+0xf7/0xb50 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff8112f87a>] ? alloc_pages_current+0xaa/0x110 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff8103a857>] ? pte_alloc_one+0x37/0x50 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff81011ea9>] ? sched_clock+0x9/0x10 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff810c0ec9>] ? trace_clock_local+0x9/0x10 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff81116885>] handle_mm_fault+0x1d5/0x350 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff81555090>] do_page_fault+0x140/0x470 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff810ce4c3>] ? trace_nowake_buffer_unlock_commit+0x43/0x60 > Jun 22 10:04:29 bluextal kernel: [ 1366.149012] [<ffffffff81015c83>] ? ftrace_raw_event_sys_exit+0xb3/ > == > > Then, waiting for some page bit...I/O of libc mapped pages ? > > Hmm. it seems buggy behavior. Okay, I'll dig this. > IIUC, because of many many threads in a small memcg, it seems a loaded page from a filesystem is dropped before mapped. Yes, it's verrrrry bad for shared pages as libc. I'll consider a way to handle shared caches in clean and scalable way. (An idea is avoiding pageout and put it to a victim cache/uncharge for avoiding ping-pong.) But it seems there are no instant fix. please wait a little. I may miss somthing... Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>