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Subject2.4 todo list update
Hi Ted,

in the last few weeks quite a few of the bugs listed on your
(excellent) have been fixed.

Here is a list of the VM bugs that are on your list and can
be moved to the "fixed" category:

* truncate->invalidate_inode_pages removes mapping information from
mapped pages which may be dirty; sync_pte -> crash. (CRITICAL)

fixed by Linus and Al

* VM: raw I/O data loss (raw IO may arrive in a page which afer it
is unammped from a process) (CRITICAL)

fixed by Linus, now page_launder() does the IO
and try_to_swap_out() only unmaps the pte

* VM: Fix the highmem deadlock, where the swapper cannot create low
memory bounce buffers OR swap out low memory because it has
consumed all resources {CRITICAL}

this was never an issue, the pagecache has been
highmem safe for a long time and the whole bounce
buffer creation has been removed

* VM: page->mapping->flush() callback in page_lauder() for easier
integration with journaling filesystem and maybe the network

page->mapping->writepage(), used from page_launder()
... now ext3, reiserfs, xfs and others need to make
their own ->writepage() function
... some semantics are still being discussed, but it's
mostly ready

* VM: maybe rebalance the swapper a bit... we do page aging now so
maybe refill_inactive_scan() / shm_swap() and swap_out() need to
be rebalanced a bit

moving shm into the page cache permanently and doing
the page down aging from refill_inactive_scan() seems
to have fixed most of this
... low priority, but may still have some room for
improvement (consider it fixed)

The following bugs _could_ be fixed ... I'm not 100% certain
but they're probably gone (could somebody confirm/deny?):

* mm->rss is modified in some places without holding the

* VFS?VM - mmap/write deadlock (demo code seems to show lock
is there)

The "probably post 2.4" category VM issues remain ... maybe
we want to add the following 2 items though:

* VM: experiment with different forms of page aging ... maybe
different aging rates for pages of different ages

* VM: RSS ulimit enforcement (trivial)


Virtual memory is like a game you can't win;
However, without VM there's truly nothing to loose...

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