On Thu, Apr 2, 2009 at 8:51 AM, Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote: > On Thursday 02 April 2009 22:34:01 Jan Kara wrote: >> On Thu 02-04-09 22:24:29, Nick Piggin wrote: >> > On Thursday 02 April 2009 09:36:13 Ying Han wrote: >> > > Hi Jan: >> > > I feel that the problem you saw is kind of differnt than mine. As >> > > you mentioned that you saw the PageError() message, which i don't see >> > > it on my system. I tried you patch(based on 2.6.21) on my system and >> > > it runs ok for 2 days, Still, since i don't see the same error message >> > > as you saw, i am not convineced this is the root cause at least for >> > > our problem. I am still looking into it. >> > > So, are you seeing the PageError() every time the problem happened? >> > >> > So I asked if you could test with my workaround of taking truncate_mutex >> > at the start of ext2_get_blocks, and report back. I never heard of any >> > response after that. >> > >> > To reiterate: I was able to reproduce a problem with ext2 (I was testing >> > on brd to get IO rates high enough to reproduce it quite frequently). >> > I think I narrowed the problem down to block allocation or inode block >> > tree corruption because I was unable to reproduce it with that hack in >> > place. >> Nick, what load did you use for reproduction? I'll try to reproduce it >> here so that I can debug ext2... > > OK, I set up the filesystem like this: > > modprobe rd rd_size=$[3*1024*1024] #almost fill memory so we reclaim buffers > dd if=/dev/zero of=/dev/ram0 bs=4k #prefill brd so we don't get alloc deadlock > mkfs.ext2 -b1024 /dev/ram0 #1K buffers > > Test is basically unmodified except I use 64MB files, and start 8 of them > at once to (8 core system, so improve chances of hitting the bug). Although I > do see it with only 1 running it takes longer to trigger. > > I also run a loop doing 'sync ; echo 3 > /proc/sys/vm/drop_caches' but I don't > know if that really helps speed up reproducing it. It is quite random to hit, > but I was able to hit it IIRC in under a minute with that setup. > Here is how i reproduce it: Filesystem is ext2 with blocksize 4096 Fill up the ram with 95% anon memory and mlockall ( put enough memory pressure which will trigger page reclaim and background writeout) Run one thread of the test program and i will see "bad pages" within few minutes. --Ying -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
