Hello Fengguang, On Tue 08-11-11 15:38:57, Wu Fengguang wrote: > On Tue, Nov 08, 2011 at 07:36:57AM +0800, Jan Kara wrote: > > today I was testing some patch with Linus' kernel from today (commit > > 31555213f03bca37d2c02e10946296052f4ecfcd) and I rather easily tripped > > out-of-memory messages and processes got killed. > > > > The unusual thing I'm doing is that I'm using user-mode-linux and > > the started virtual machine has relatively low amount of memory (I was > > tripping OOM immediately with mem=64M or mem=128M, I could still hit it > > after a while with mem=256M). The load I was running was just "dd > > if=/dev/zero of=/tmp/file bs=128k". The backing filesystem was ext3. Now > > with older kernel (e.g. 3.1) running even with mem=64M was fine. > > > > Example of an OOM message: > > > > dd invoked oom-killer: gfp_mask=0x200da, order=0, oom_adj=0, > > oom_score_adj=0 > > Call Trace: > > 6ff5b868: [<602f550d>] _raw_spin_unlock+0x9/0xb > > 6ff5b878: [<6005ad53>] dump_header.clone.2+0xba/0x1b6 > > 6ff5b8b8: [<6005af77>] oom_kill_process.clone.0+0x45/0x236 > > 6ff5b928: [<6005b506>] out_of_memory+0x25c/0x305 > > 6ff5b9a8: [<6005e563>] __alloc_pages_nodemask+0x558/0x5fd > > 6ff5ba08: [<60270a2b>] radix_tree_lookup_slot+0xe/0x10 > > 6ff5ba88: [<60065933>] shmem_getpage_gfp+0x269/0x475 > > 6ff5bb18: [<60065b72>] shmem_write_begin+0x33/0x35 > > 6ff5bb28: [<60059fa4>] generic_file_buffered_write+0x132/0x28f > > 6ff5bbf8: [<6005a47a>] __generic_file_aio_write+0x379/0x3b5 > > 6ff5bcb8: [<6005a53a>] generic_file_aio_write+0x84/0xdd > > 6ff5bd28: [<6007fb09>] do_sync_write+0xd1/0x10e > > 6ff5bdc8: [<600174c1>] segv+0x8f/0x24a > > 6ff5be58: [<6007fc0b>] vfs_write+0xc5/0x16d > > 6ff5be98: [<6007fd64>] sys_write+0x45/0x6c > > 6ff5bed8: [<60017e48>] handle_syscall+0x50/0x70 > > 6ff5bef8: [<60024ae6>] userspace+0x320/0x3d6 > > 6ff5bfc8: [<600151ac>] fork_handler+0x7d/0x84 > > > > Mem-Info: > > Normal per-cpu: > > CPU 0: hi: 90, btch: 15 usd: 0 > > active_anon:850 inactive_anon:59583 isolated_anon:0 > > active_file:0 inactive_file:16 isolated_file:0 > > unevictable:0 dirty:0 writeback:0 unstable:0 > > free:510 slab_reclaimable:540 slab_unreclaimable:461 > > mapped:0 shmem:59685 pagetables:111 bounce:0 > > Normal free:2040kB min:2032kB low:2540kB high:3048kB active_anon:3400kB > > inactive_anon:238332kB active_file:0kB inactive_file:64kB unevictable:0kB > > isolated(anon):0kB isolated(file):0kB present:258560kB mlocked:0kB > > dirty:0kB writeback:0kB mapped:0kB shmem:238740kB slab_reclaimable:2160kB > > It looks most present pages are consumed by shmem/inactive_anon. Do > you have idea what's the shmem used for? Hmm, I must have messed up something during my testing. It looks as if I was writing to some tmpfs filesystem instead of the test filesystem I wanted to use (and that brought the system OOM). Now when I use the right filesystem, I'm not able to hit the OOM anymore. So sorry for the noise. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- 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>