Re: [RFC][PATCH 1/3] radix priority search tree - objrmap complexity fix

Andrea Arcangeli
2004-03-31T17:28:51Z

On Wed, Mar 31, 2004 at 05:45:31PM +0100, Hugh Dickins wrote:
> On Wed, 31 Mar 2004, Andrea Arcangeli wrote:
> >
> > So I rewritten the fix this way:
> >
> > + ret = add_to_swap_cache(page, entry);
>
> I think you'll find that gets into trouble on the header page,
> entry 0, which pmdisk/swsusp does access through this interface,
> but swapping does not: I'd expect its swap_duplicate to fail.

I didn't know they have to modify the header page.

> I've put off dealing with this, wasn't a priority for me to
> decide what to do with it. You might experiment with setting
> p->swap_map[0] = 1 instead of SWAP_MAP_BAD in sys_swapon, but
> offhand I'm unsure whether that's enough e.g. would the totals
> come out right, would swapoff complete?
>
> Just an idea, not something to finalize.

if they run into trouble I'll return to the pagecache API adding the
GFP_KERNEL and check for oom failure.