Need some help for "out of memory",Thanks everyone

[powertoys]

My os' version is redhat as4.
My recent system messages like this:

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Feb 24 17:59:25 galaxy kernel: oom-killer: gfp_mask=0xd0
Feb 24 17:59:25 galaxy kernel: DMA per-cpu:
Feb 24 17:59:25 galaxy kernel: cpu 0 hot: low 2, high 6, batch 1
Feb 24 17:59:25 galaxy kernel: cpu 0 cold: low 0, high 2, batch 1
Feb 24 17:59:25 galaxy kernel: Normal per-cpu:
Feb 24 17:59:25 galaxy kernel: cpu 0 hot: low 32, high 96, batch 16
Feb 24 17:59:25 galaxy kernel: cpu 0 cold: low 0, high 32, batch 16
Feb 24 17:59:25 galaxy kernel: HighMem per-cpu:
Feb 24 17:59:25 galaxy kernel: cpu 0 hot: low 32, high 96, batch 16
Feb 24 17:59:25 galaxy kernel: cpu 0 cold: low 0, high 32, batch 16
Feb 24 17:59:25 galaxy kernel:
Feb 24 17:59:25 galaxy kernel: Free pages: 534464kB (534144kB HighMem)
Feb 24 17:59:25 galaxy kernel: Active:137019 inactive:22491 dirty:0 writeback:0 unstable:0 free:133616 slab:222034 mapped:129123 pagetables:1103
Feb 24 17:59:26 galaxy kernel: DMA free:8kB min:16kB low:32kB high:48kB active:0kB inactive:0kB present:16384kB
Feb 24 17:59:26 galaxy kernel: protections[]: 0 0 0
Feb 24 17:59:26 galaxy kernel: Normal free:312kB min:936kB low:1872kB high:2808kB active:220kB inactive:0kB present:901120kB
Feb 24 17:59:26 galaxy kernel: protections[]: 0 0 0
Feb 24 17:59:26 galaxy kernel: HighMem free:534144kB min:512kB low:1024kB high:1536kB active:547856kB inactive:89964kB present:1179392kB
Feb 24 17:59:26 galaxy kernel: protections[]: 0 0 0
Feb 24 17:59:26 galaxy kernel: DMA: 0*4kB 1*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 8kB
Feb 24 17:59:26 galaxy kernel: Normal: 0*4kB 1*8kB 1*16kB 1*32kB 0*64kB 0*128kB 1*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 312kB
Feb 24 17:59:26 galaxy kernel: HighMem: 914*4kB 695*8kB 2156*16kB 596*32kB 477*64kB 884*128kB 380*256kB 162*512kB 46*1024kB 37*2048kB 6*4096kB = 534144kB
Feb 24 17:59:26 galaxy kernel: Swap cache: add 42909, delete 22293, find 13901/16521, race 0+0
Feb 24 17:59:26 galaxy kernel: Out of Memory: Killed process 19388 (java).
Feb 24 17:59:26 galaxy kernel: Out of Memory: Killed process 19396 (java).
Feb 24 17:59:26 galaxy kernel: Out of Memory: Killed process 19397 (java).
Feb 24 17:59:26 galaxy kernel: Out of Memory: Killed process 19398 (java).
Feb 24 17:59:26 galaxy kernel: Out of Memory: Killed process 19399 (java).
Feb 24 17:59:26 galaxy kernel: Out of Memory: Killed process 19400 (java).
Feb 24 17:59:26 galaxy kernel: Out of Memory: Killed process 19401 (java).
Feb 24 17:59:27 galaxy kernel: Out of Memory: Killed process 19402 (java).
Feb 24 17:59:28 galaxy kernel: Out of Memory: Killed process 19403 (java).
Feb 24 17:59:33 galaxy kernel: Out of Memory: Killed process 19404 (java).
Feb 24 17:59:33 galaxy kernel: Out of Memory: Killed process 19405 (java).
Feb 24 17:59:33 galaxy kernel: Out of Memory: Killed process 19406 (java).
Feb 24 17:59:35 galaxy kernel: Out of Memory: Killed process 19408 (java).
Feb 24 17:59:36 galaxy kernel: Out of Memory: Killed process 19410 (java).
Feb 24 17:59:36 galaxy kernel: Out of Memory: Killed process 19411 (java).
Feb 24 17:59:36 galaxy kernel: Out of Memory: Killed process 19412 (java).
Feb 24 17:59:36 galaxy kernel: Out of Memory: Killed process 19413 (java).
Feb 24 17:59:36 galaxy kernel: Out of Memory: Killed process 19414 (java).
Feb 24 17:59:36 galaxy kernel: Out of Memory: Killed process 19415 (java).
Feb 24 17:59:36 galaxy kernel: Out of Memory: Killed process 19420 (java).
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I think there must be something wrong with my system.
Thanks for you help!