[Yaffs] bad block problem

Hello All
I am using ARM(S3C2410) machine with 2.4.18 kernel, yaffs and mtd. I have
2 partitions to store data, At first, allthings was all right, but the
bad blocks number had grown incrumently. After 2 or 3 month past, one of my
partition is full and on more available space left.


[root /data0]#df
Filesystem 1k-blocks Used Available Use% Mounted on
/dev/mtdblock/4 2032 1836 196 90% /home
/dev/mtdblock/5 5104 5104 0 100% /data0
/dev/mtdblock/6 5104 1928 3176 38% /data1

The total size of all files in direcorty data0 is not more than
4.0Mbytes. And some blocks of this partition is marked bad.
[root /data0]#more /proc/kmsg
...
<7>block 228 is bad
<7>block 234 is bad
<7>block 235 is bad
<7>block 236 is bad
<7>block 249 is bad
<7>block 250 is bad
<7>block 251 is bad
<7>block 252 is bad
<7>block 256 is bad
<7>block 258 is bad
<7>block 259 is bad
<7>block 261 is bad
<7>block 263 is bad
<7>block 264 is bad
<7>block 266 is bad
<7>block 268 is bad
<7>block 270 is bad
<7>block 272 is bad
<7>block 274 is bad
<7>block 276 is bad
<7>block 279 is bad
--More--
....
....

My yaffs configuration is here.
[root /data0]#more /proc/yaffs
YAFFS built:Oct 16 2003 09:25:52
$Id: yaffs_fs.c,v 1.26 2003/05/20 23:20:53 charles Exp $
$Id: yaffs_guts.c,v 1.26 2003/05/20 23:20:53 charles Exp $

Device yaffs
startBlock......... 1
endBlock........... 319
chunkGroupBits..... 0
chunkGroupSize..... 1
nErasedBlocks...... 187
nTnodesCreated..... 200
nFreeTnodes........ 67
nObjectsCreated.... 100
nFreeObjects....... 66
nFreeChunks........ 6483
nPageWrites........ 3294
nPageReads......... 5155
nBlockErasures..... 51
nGCCopies.......... 77
garbageCollections. 51
passiveGCs......... 51
nRetriedWrites..... 0
nRetireBlocks...... 0
eccFixed........... 0
eccUnfixed......... 0
tagsEccFixed....... 0
tagsEccUnfixed..... 191
cacheHits.......... 0
nDeletedFiles...... 18
nUnlinkedFiles..... 18
nBackgroudDeletions 0
useNANDECC......... 1


I can regain the bad blocks by using the low level flash utility. I use
"vivi" to boot my machine, and the "vivi" has a function to format the
flash.
I wonder why this happens and how to solve this problem.

Best regards
Fanlvu