Re: [BUG?] possible recursive locking detected

From: Andrew Morton
Date: Thu Jul 27 2006 - 03:36:10 EST


On Thu, 27 Jul 2006 08:15:27 +0100
Anton Altaparmakov <aia21@xxxxxxxxx> wrote:

> > I'm surprised ext2 is allocating with __GFP_FS set, though. Would that
> > cause any problem?
>
> That is an ext2 bug IMO.

There is no bug.

What there is is an ill-defined set of rules. If we want to tighten these
rules we have a choice between

a) Never enter page reclaim while holding i_mutex or

b) never take i_mutex on the page reclaim path.


Implementing a) would be a disaster. It means that our main write()
implementation in mm/filemap.c (which holds i_mutex) wouldn't be able to
reclaim pages to satisfy the write. And generally, we do want to use the
strongest memory allocation mode at all times.

So we'll have a better kernel if we implement b).
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