linux-kernel - Re: kernel BUGs when removing largish files with the SLOB allocator

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Message-ID: <6626.1158094964@warthog.cambridge.redhat.com>
Date:	Tue, 12 Sep 2006 22:02:44 +0100
From:	David Howells <dhowells@...hat.com>
To:	Matt Mackall <mpm@...enic.com>
Cc:	David Howells <dhowells@...hat.com>, Aubrey <aubreylee@...il.com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	linux-kernel@...r.kernel.org, davidm@...pgear.com,
	gerg@...pgear.com
Subject: Re: kernel BUGs when removing largish files with the SLOB allocator 

Matt Mackall <mpm@...enic.com> wrote:

> Not sure yet. There's only one user in nommu.c that shouldn't just be
> changed to ksize() that I can see, and that's the one in
> show_process_blocks(). That could test for VM_MAPPED_COPY and keep its
> hands off otherwise. 

Hmmm...  You're right.  However, note binfmt_elf_fdpic().  This calls ksize()
but should really call kobjsize().  It should not assume that the allocation
it's been given is of any particular type.  IIRC ksize() changed purpose at
some point.

> I can imagine situations where ->mmap returns pointers to something
> that's statically allocated anyway (XIP?), where kobjsize doesn't
> really make sense.

ramfs for example.  See get_unmapped_area() hooks, not mmap() hooks.

> Also, looks like the WARN_ON_SLACK code has rotten, result isn't
> defined in that function. Change it to base, perhaps?

Yeah.  It might be worth ditching it entirely too.

David
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