Re: [patch?] Re: Do ramdisk exec's map direct to buffer cache?

From: Mike Galbraith (mikeg@weiden.de)
Date: Tue Aug 01 2000 - 11:06:00 EST


On Tue, 1 Aug 2000, Andrea Arcangeli wrote:

> On Mon, 31 Jul 2000, Linus Torvalds wrote:
>
> >do something like
> >
> > int wait;
> >
> > if (!(gfp_mask & __GFP_IO))
> > goto unlock_continue;
> > wait = nr_dirty-- < 0;
>
> We still want to recycle the clean buffers from a GFP_BUFFER allocation.
> The fix I prefer is to pass gfp_mask to try_to_free_buffers and to call
> sync_page_buffers only if __GFP_IO was set (checking for it inside
> try_to_free_buffers).

Linus's fix seems to do the trick. I beat on it _very hard_ for four
hours and couldn't lock it. I'll try your suggestion too. The only
thing I saw during pounding is that heavy swapping to a loop device
is dog slow.. and maybe a little silly :) but it ran without locking.

Linus: There is something very odd going on though...
If I mount -oloop /usr/local and try a make -j30, I see read corruption
(cpp carping) as soon as memory pressure hits. If I start with /usr/local
mounted, and mount -oremount,loop all is well. (repeatable) When in
corruption mode, it will nibble on the underlying fs, so writes are being
corrupted too. I've found blocks of zeros replacing various data blocks in
the recent past after tinker sessions. (no damage noted today)
That's why I agreed with DANGEROUS.. it can nibble an fs pretty badly if
you play with it long enough when it's in this.. bad mood.

        -Mike

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