Re: Lockups with 2.4.14 and 2.4.16

From: Andrew Morton (
Date: Fri Dec 14 2001 - 12:26:42 EST

Chris Mason wrote:
> Ok, Johan sent along stack traces, and the deadlock works a little like this:
> linux-2.4.16 + reiserfs + quota v2
> kswapd ->
> prune_icache->dispose_list->dquot_drop->commit_dquot->generic_file_write->
> mark_inode_dirty->journal_begin-> wait for trans to end


> Some process in the transaction is waiting on kswapd to free ram.

This is unfamiliar. Where does a process block on kswapd in this
manner? Not __alloc_pages I think.
> So, this will hit any journaled FS that uses quotas and logs inodes under
> during a write. ext3 doesn't seem to do special things for quota anymore, so
> it should be affected too.

mm.. most of the ext3 damage-avoidance hacks are around writepage().

> The only fix I see is to make sure kswapd doesn't run shrink_icache, and to
> have it done via a dedicated daemon instead. Does anyone have a better idea?

Well, we already need to do something like that to prevent the
abuse of keventd in there. It appears that somebody had a
problem with deadlocks doing the inode writeout in kswapd but
missed the quota problem.

Is it possible for the quota code to just bale out if PF_MEMALLOC
is set? To leave the dquot dirty?

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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:28 EST