Messages in this thread | | | Date | Wed, 19 Aug 2009 11:44:08 +0900 | From | Minchan Kim <> | Subject | Re: abnormal OOM killer message |
| |
On Wed, 19 Aug 2009 10:41:51 +0900 우충기 <chungki.woo@gmail.com> wrote:
> Hi all~ > I have got a log message with OOM below. I don't know why this > phenomenon was happened. > When direct reclaim routine(try_to_free_pages) in __alloc_pages which > allocates kernel memory was failed, > one last chance is given to allocate memory before OOM routine is executed. > And that time, allocator uses ALLOC_WMARK_HIGH to limit watermark. > Then, zone_watermark_ok function test this value with current memory > state and decide 'can allocate' or 'cannot allocate'. > > Here is some kernel source code in __alloc_pages function to understand easily. > Kernel version is 2.6.18 for arm11. Memory size is 32Mbyte. And I use > compcache(0.5.2). > ------------------------------------------------------------------------------------------------------------------------------------------------------------- > ... > did_some_progress = try_to_free_pages(zonelist->zones, > gfp_mask); <== direct page reclaim > > p->reclaim_state = NULL; > p->flags &= ~PF_MEMALLOC; > > cond_resched(); > > if (likely(did_some_progress)) { > page = get_page_from_freelist(gfp_mask, order, > zonelist, alloc_flags); > if (page) > goto got_pg; > } else if ((gfp_mask & __GFP_FS) && !(gfp_mask & > __GFP_NORETRY)) { <== when fail to reclaim > /* > * Go through the zonelist yet one more time, keep > * very high watermark here, this is only to catch > * a parallel oom killing, we must fail if we're still > * under heavy pressure. > */ > page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, > order, <== this is last chance > zonelist, > ALLOC_WMARK_HIGH|ALLOC_CPUSET); <== uses > ALLOC_WMARK_HIGH > if (page) > goto got_pg; > > out_of_memory(zonelist, gfp_mask, order); > goto restart; > } > ... > ------------------------------------------------------------------------------------------------------------------------------------------------------------- > > In my case, you can see free pages(6804KB) is much more higher than > high watermark value(1084KB) in OOM message. > And order of allocating is also zero.(order=0) > In buddy system, the number of 4kbyte page is 867. > So, I think OOM can't be happend. >
Yes. I think so.
In that case, even we can also avoid zone defensive algorithm.
> How do you think about this? > Is this side effect of compcache?
I don't know compcache well. But I doubt it. Let's Cced Nitin.
> Please explain me. > Thanks. > > This is OOM message. > ------------------------------------------------------------------------------------------------------------------------------------------------------------- > oom-killer: gfp_mask=0x201d2, order=0 (==> __GFP_HIGHMEM, > __GFP_WAIT, __GFP_IO, __GFP_FS, __GFP_COLD) > [<c00246c0>] (dump_stack+0x0/0x14) from [<c006ba68>] (out_of_memory+0x38/0x1d0) > [<c006ba30>] (out_of_memory+0x0/0x1d0) from [<c006d4cc>] > (__alloc_pages+0x244/0x2c4) > [<c006d288>] (__alloc_pages+0x0/0x2c4) from [<c006f054>] > (__do_page_cache_readahead+0x12c/0x2d4) > [<c006ef28>] (__do_page_cache_readahead+0x0/0x2d4) from [<c006f594>] > (do_page_cache_readahead+0x60/0x64) > [<c006f534>] (do_page_cache_readahead+0x0/0x64) from [<c006ac24>] > (filemap_nopage+0x1b4/0x438) > r7 = C0D8C320 r6 = C1422000 r5 = 00000001 r4 = 00000000 > [<c006aa70>] (filemap_nopage+0x0/0x438) from [<c0075684>] > (__handle_mm_fault+0x398/0xb84) > [<c00752ec>] (__handle_mm_fault+0x0/0xb84) from [<c0027614>] > (do_page_fault+0xe8/0x224) > [<c002752c>] (do_page_fault+0x0/0x224) from [<c0027900>] > (do_DataAbort+0x3c/0xa0) > [<c00278c4>] (do_DataAbort+0x0/0xa0) from [<c001fde0>] > (ret_from_exception+0x0/0x10) > r8 = BE9894B8 r7 = 00000078 r6 = 00000130 r5 = 00000000 > r4 = FFFFFFFF > Mem-info: > DMA per-cpu: > cpu 0 hot: high 6, batch 1 used:0 > cpu 0 cold: high 2, batch 1 used:1 > DMA32 per-cpu: empty > Normal per-cpu: empty > HighMem per-cpu: empty > Free pages: 6804kB (0kB HighMem) > Active:101 inactive:1527 dirty:0 writeback:0 unstable:0 free:1701 > slab:936 mapped:972 pagetables:379 > DMA free:6804kB min:724kB low:904kB high:1084kB active:404kB > inactive:6108kB present:32768kB pages_scanned:0 all_unreclaimable? no > lowmem_reserve[]: 0 0 0 0 > DMA32 free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB > present:0kB pages_scanned:0 all_unreclaimable? no > lowmem_reserve[]: 0 0 0 0 > Normal free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB > present:0kB pages_scanned:0 all_unreclaimable? no > lowmem_reserve[]: 0 0 0 0 > HighMem free:0kB min:128kB low:128kB high:128kB active:0kB > inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no > lowmem_reserve[]: 0 0 0 0 > DMA: 867*4kB 273*8kB 36*16kB 2*32kB 0*64kB 0*128kB 0*256kB 1*512kB > 0*1024kB 0*2048kB 0*4096kB = 6804kB > DMA32: empty > Normal: empty > HighMem: empty > Swap cache: add 4597, delete 4488, find 159/299, race 0+0 > Free swap = 67480kB > Total swap = 81916kB
In addition, total swap : 79M??
> Free swap: 67480kB > 8192 pages of RAM > 1960 free pages > 978 reserved pages > 936 slab pages > 1201 pages shared > 109 pages swap cached
free page : 6M page table + slab + reserved : 8M active + inacive : 6M
Where is 12M?
> Out of Memory: Kill process 47 (rc.local) score 849737 and children. > Out of memory: Killed process 49 (CTaskManager). > Killed > SW image is stopped.. > script in BOOT is stopped... > Starting pid 348, console /dev/ttyS1: '/bin/sh' > -sh: id: not found > # > -------------------------------------------------------------------------------------------------------------------------------------------------------------
As you mentioned, your memory size is 32M and you use compcache. How is swap size bigger than your memory size ? Is the result of compression of swap pages ? Nitin. Could you answer the question?
I can't imagine whey order 0 allocation failed although there are many pages in buddy.
What do you mm guys think about this problem ?
-- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |