Messages in this thread | | | Date | Sat, 21 Jan 2006 23:20:08 +0000 | From | Pavel Machek <> | Subject | Re: Recursive chmod/chown OOM kills box with 32MB RAM |
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Hi!
> > >[CCing namesys] > > > > > >Narrowed it down to 100% reproducible case: > > > > > > chown -Rc 0:<n> . > > > > > >in a top directory of tree containing ~21938 files > > >on reiser3 partition: > > > > > > /dev/sdc3 on /.3 type reiserfs (rw,noatime) > > > > > >causes oom kill storm. "ls -lR", "find ." etc work fine. > > > > > >I suspected that it is a leak in winbindd libnss module, > > >but chown does not seem to grow larger in top, and also > > >running it under softlimit -m 400000 still causes oom kills > > >while chown's RSS stays below 4MB. > > In order for the journaled filesystems to make sure the FS is consistent after > a crash, we need to keep some blocks in memory until other blocks have been > written. These blocks are pinned, and can't be freed until a certain amount > of io is done. > > In the case of reiserfs, it might pin as much as the size of the journal at > any time. The default journal is 32MB, which is much too large for a system > with only 32MB of ram. > > You can shrink the log of an existing filesystem. The minimum size is 513 > blocks, you might try 1024 as a good starting poing. > > reiserfstune -s 1024 /dev/xxxx > > The filesystem must be unmounted first.
Could we refuse to mount filesystem unless journal_size < physmem_size/2 or something like that?
I was not aware of this trap, and it seems unlikely that users know about it... Pavel -- Thanks, Sharp! - 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/
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