BTW, here's some debug information from /var/log/kern.log :

May  3 19:51:22 yoda kernel: [10632.509889] Out of memory: kill process 9047 (apache2) score 19040 or a child
May  3 19:51:22 yoda kernel: [10632.510045] Killed process 9047 (apache2)
May  3 19:51:22 yoda kernel: [10634.310259] named invoked oom-killer: gfp_mask=0x1201d2, order=0, oomkilladj=0
May  3 19:51:22 yoda kernel: [10634.310291] Pid: 4539, comm: named Not tainted 2.6.24-16-server #1
May  3 19:51:22 yoda kernel: [10634.310370]  [oom_kill_process+0x10a/0x120] oom_kill_process+0x10a/0x120
May  3 19:51:22 yoda kernel: [10634.310460]  [out_of_memory+0x167/0x1a0] out_of_memory+0x167/0x1a0
May  3 19:51:22 yoda kernel: [10634.310510]  [agpgart:__alloc_pages+0x34c/0x380] __alloc_pages+0x34c/0x380
May  3 19:51:22 yoda kernel: [10634.310573]  [filemap_fault+0x10a/0x420] filemap_fault+0x10a/0x420
May  3 19:51:22 yoda kernel: [10634.310638]  [__do_fault+0x83/0x4c0] __do_fault+0x83/0x4c0
May  3 19:51:22 yoda kernel: [10634.310747]  [handle_mm_fault+0x21b/0xb80] handle_mm_fault+0x21b/0xb80
May  3 19:51:22 yoda kernel: [10634.310778]  [<c012b0c0>] default_wake_function+0x0/0x10
May  3 19:51:22 yoda kernel: [10634.310875]  [sched_clock+0x13/0x30] sched_clock+0x13/0x30
May  3 19:51:22 yoda kernel: [10634.310914]  [snd_pcm:getnstimeofday+0x34/0x9790] getnstimeofday+0x34/0xf0
May  3 19:51:22 yoda kernel: [10634.310966]  [snd_pcm:ktime_get_ts+0x1e/0x4f0] ktime_get_ts+0x1e/0x60
May  3 19:51:22 yoda kernel: [10634.310996]  [do_page_fault+0x143/0x900] do_page_fault+0x143/0x900
May  3 19:51:22 yoda kernel: [10634.311025]  [sys_futex+0x98/0x120] sys_futex+0x98/0x120
May  3 19:51:22 yoda kernel: [10634.311054]  [snd_seq:do_gettimeofday+0x34/0xa450] do_gettimeofday+0x34/0xe0
May  3 19:51:22 yoda kernel: [10634.311090]  [sys_gettimeofday+0x28/0x80] sys_gettimeofday+0x28/0x80
May  3 19:51:22 yoda kernel: [10634.311118]  [do_page_fault+0x0/0x900] do_page_fault+0x0/0x900
May  3 19:51:22 yoda kernel: [10634.311134]  [error_code+0x72/0x78] error_code+0x72/0x78
May  3 19:51:22 yoda kernel: [10634.311173]  [unix_create1+0x50/0x120] unix_create1+0x50/0x120
May  3 19:51:22 yoda kernel: [10634.311229]  =======================
May  3 19:51:22 yoda kernel: [10634.311236] Mem-info:
May  3 19:51:22 yoda kernel: [10634.311243] DMA per-cpu:
May  3 19:51:22 yoda kernel: [10634.311253] CPU    0: Hot: hi:    0, btch:   1 usd:   0   Cold: hi:    0, btch:   1 usd:   0
May  3 19:51:22 yoda kernel: [10634.311264] Normal per-cpu:
May  3 19:51:22 yoda kernel: [10634.311273] CPU    0: Hot: hi:  186, btch:  31 usd:  87   Cold: hi:   62, btch:  15 usd:  43
May  3 19:51:22 yoda kernel: [10634.311291] Active:87819 inactive:295 dirty:0 writeback:0 unstable:0
May  3 19:51:22 yoda kernel: [10634.311297]  free:976 slab:3176 mapped:2 pagetables:1570 bounce:0
May  3 19:51:22 yoda kernel: [10634.311314] DMA free:1552kB min:104kB low:128kB high:156kB active:10208kB inactive:16kB present:16256kB pages_scanned:127731 all_unreclaimable? yes
May  3 19:51:22 yoda kernel: [10634.311327] lowmem_reserve[]: 0 364 364 364
May  3 19:51:22 yoda kernel: [10634.311347] Normal free:2352kB min:2384kB low:2980kB high:3576kB active:341068kB inactive:1164kB present:372812kB pages_scanned:706813 all_unreclaimable? yes
May  3 19:51:22 yoda kernel: [10634.311361] lowmem_reserve[]: 0 0 0 0
May  3 19:51:22 yoda kernel: [10634.311375] DMA: 0*4kB 0*8kB 1*16kB 0*32kB 0*64kB 0*128kB 0*256kB 1*512kB 1*1024kB 0*2048kB 0*4096kB = 1552kB
May  3 19:51:22 yoda kernel: [10634.311407] Normal: 18*4kB 1*8kB 1*16kB 0*32kB 1*64kB 1*128kB 2*256kB 1*512kB 1*1024kB 0*2048kB 0*4096kB = 2336kB
May  3 19:51:22 yoda kernel: [10634.311443] Swap cache: add 0, delete 0, find 0/0, race 0+0
May  3 19:51:22 yoda kernel: [10634.311452] Free swap  = 0kB
May  3 19:51:22 yoda kernel: [10634.311458] Total swap = 0kB
May  3 19:51:22 yoda kernel: [10634.311464] Free swap:            0kB
May  3 19:51:22 yoda kernel: [10634.338503] 98032 pages of RAM
May  3 19:51:22 yoda kernel: [10634.338519] 0 pages of HIGHMEM
May  3 19:51:22 yoda kernel: [10634.338525] 1953 reserved pages
May  3 19:51:22 yoda kernel: [10634.338531] 246726 pages shared
May  3 19:51:22 yoda kernel: [10634.338537] 0 pages swap cached
May  3 19:51:22 yoda kernel: [10634.338543] 0 pages dirty
May  3 19:51:22 yoda kernel: [10634.338548] 0 pages writeback
May  3 19:51:22 yoda kernel: [10634.338554] 2 pages mapped
May  3 19:51:22 yoda kernel: [10634.338560] 3176 pages slab
May  3 19:51:22 yoda kernel: [10634.338565] 1570 pages pagetables