There's a new pre-patch for 2.2.3, one that I was already going to make
the final 2.2.3, but I decided that I'm chicken after all, and that I
might as well let some people check that it's sane.
This pre-2.2.3 does:

 - Fix some silly NFS problems. Some of them can be quite bad: lost error
   notification of asynchronous writes, which can result in horrible
   problems (including lost email etc). Most people wouldn't ever notice,
   so don't panic, but forgetting about the error notification certainly
   counts as a brown paper bag.
 - Alpha should compile and work again
 - Various driver updates. This is actually the bulk of the patch, with
   IRDA updates, some scsi, video and sound driver updates etc.
 - The "mmap forgets about the file that was mapped" bug that has been
   discussed here. Only affected certain drivers.
 - shaper atomicity fixes
 - various minor TCP fixes
 - buffer growth fix and recursive IO memory reclaim fix from Andrea
 - network filter compiles ;)
 - unix gc fixes

Tell me if you see problems, because I'm going to release it as 2.2.3
unless people tell me otherwise..

                Linus

In a superhuman effort to not get killed by my wife, I delayed the latest
release for a day. And in fact, it's still just a pre-release, because I
wanted to check with Ingo that I have his latest IO-APIC code with the
proper handling of ExtINT. Ingo?

Anyway, the "not quite valentine days release" (also known as the "horny
greased weasel", aka "presidents day" release ;), is right now a pre-patch
on ftp.kernel.org: /pub/linux/kernel/testing/pre-patch-2.2.2-4.gz.

Happily, I haven't heard of any new real show-stoppers, which is good
(especially considering the fact that I gave it an extra week just to hear
if somebody could come up with some new problems). The things fixed
relative to 2.2.1 are:

 - the inode thing. If you don't know, don't worry.
 - config scripts updated
 - IO-APIC cleanups and fixes, so that people with strange motherboards
   should be able to reboot cleanly and not get unexpected interrupts.
 - 2kB sector media (ie mostly MO) fixes. See all the warnings on the
   lists about fdisk confusion etc if you have one of these things.
 - IDE disk cleanups/fixes (geometry and autodetection)
 - PS/2 mouse hides ACK's again
 - pty crash fix
 - some network driver fixes (out-of-memory and shared interrupts)
 - some sound and video updates.
 - lockd cookie fixes
 - nfsd readdir reply cache fix
 - filesystem/VM deadlock avoidance (new deamon: kpiod)
 - SMP scheduler race condition (which nobody has probably ever seen)
 - TCP socket locking fix

Most of the above are really hard to see in the first place, and not
something most people would ever hit (with the possible exception of the
inode thang).  But it would be good to have a really rock solid 2.2.2, so
if people could just bother to check that it works for them, and I'll make
this official tomorrow.

                Linus

this one contains various small documentation updates and updates to xconfig,
but the important parts (and the smallest part of the actual patch) are:

 - shared file lockup fix by Stephen Tweedie
 - my fix for the TCP bug that Ingo found
 - Ingo's io-apic setup fixes, which should finally get rid of the
   spurious apic interrupts with some motherboards and the ExtINT setup.
 - inode leak thing
 - SMP scheduler potential race condition fix
 - sound driver updates
 - partition and disk fixes (2kB blocksize media and some IDE disk
   geometry and irq detection issues).

None of the fixes are critical to most people, but all of them _can_ be
critical to people who have seen vulnerabilities in the area. As such, if
you're happy with 2.2.1 there is no pressing reason to test this patch
out, but I hope to have the pre-patches so that the final 2.2.2 can be
left around for a while (CD-ROM manufacturers etc would certainly prefer
to not see lots of releases).

                Linus

The subject says it all. We did have a few paper-bag-inducing bugs in
2.2.0, so there's a 2.2.1 out there now, just a few days after 2.2.0.
Oh, well. These things happen,

                Linus

- the stupid off-by-one bug 'execute a coredump' crash found by Ingo
- __down_interruptible on alpha
- move "esstype" to outside a #ifdef MODULE
- NFSD rename/rmdir fixes
- revert to old array.c
- change comment about __PAGE_OFFSET
- missing "vma = NULL" case for avl find_vma()

> Compile this code
>
> ---- cut here ----
> #include <fcntlbits.h>
> void main( int argc, char *argv[] ) {
>         open( argv[ 1 ], O_WRONLY|O_CREAT|O_TRUNC, 0666 );
> }
> ---- and here  ----
>
> and run it like this
>
>     strace ./a.out >(cat - )
>
> with 2.0.36 & 2.2.0-pre[67] you get:
>
>     open("/dev/fd/63", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
>
> with 2.2.0-pre[89] you get:
>
>     open("/dev/fd/63", O_WRONLY|O_CREAT|O_TRUNC, 0666) = -1 ENOENT (No
> such file or directory)

Ok, this seems to be due to pre9 removing some rather bogus code that
happened to hide another problem in open_namei().
I haven't actually tested this, but it looks really obvious, so does this
patch fix it for you? (This should also fix a potential performance
bogosity - there's absolutely no reason why we should get the directory
lock when we don't need to for a normal open of an existing file).

                Linus

Hoya,
 there's now a 2.2.0-pre9 on ftp.kernel.org, and when you compile it it
will call itself 2.2.0-final. The reason is fairly obvious: enough is
enough, and I can't make pre-kernels forever, it just dilutes the whole
idea. The only reason the tar-file is not called 2.2.0 is that I want to
avoid having any embarrassing typos that cause it to not compile under
reasonable configurations or something like that. Unreasonable
configurations I no longer care about.

Every program has bugs, and I'm sure there are still bugs in this. Get
over it - we've done our best, and nobody ever believed that there
wouldn't be 2.2.x kernels to fix problems as they come up, and delaying
2.2.0 forever is not an option.

I have a wedding anniversary and a company party coming up, so I'm taking
a few days off - when I get back I expect to take this current 2.2.0-final
and just remove the "-final" from the Makefile, and that will be it. I
suspect somebody _will_ find something embarrassing enough that I would
fix it too, but let's basically avoid planning on that.
In short, before you post a bug-report about 2.2.0-final, I'd like you to
have the following simple guidelines:
 "Is this something Linus would be embarrassed enough about that he would
  wear a brown paper bag over his head for a month?"
and
 "Is this something that normal people would ever really care deeply
  about?"

If the answer to either question is "probably not", then please consider
just politely discussing it as a curiosity on the kernel mailing lists
rather than even sending email about it to me: I've been too busy the last
few weeks, and I'd really appreciate it if I could just forget the worries
of a release for a few days..

But if you find something hilariously stupid I did, feel free to share it
with me, and we'll laugh about it together (and I'll avoid wearing the
brown paper bag on my head during the month of February). Do we have a
deal?

I've seen people working on a 2.2.0 announcement, and I'm happy - I've
been too busy to think straight, much less worry about details like that.
If everything turns out ok, I'll have a few memorable bloopers in my
mailbox but nothing worse than that, and I can sit down and actually read
the announcement texts that people have been discussing.

ObFeatures:
 - m68k sync
 - various minor driver fixes (irda, net drivers, scsi, video, isdn)
 - SGI Visual Workstation support
 - adjtimex update to the latest standards
 - vfat silly buglet fix
 - semaphores work on alpha again
 - drop the inline strstr() that gcc got wrong whatever we did
 - kswapd needed to be a bit more aggressive
 - minor TCP retransmission and delack fixes
Until Monday,
                        Linus

Ok, I think I now know why pre-6 looks so unbalanced. It's two issues.
Basically, trying to swap out a large number of pages from one process
context is just doomed. It bascially sucks, because

 - it has bad latency. This is further excerberated by the per-process
   "thrashing_memory" flag, which means that if we were unlucky enough to
   be selected to be the process that frees up memory, we'll probably be
   stuck with it for a long time. That can make it extremely unfair under
   some circumstances - other processes may allocate the pages we free'd
   up, so that we keep on being counted as a memory trasher even if we
   really aren't.
   Note that this shows most under "moderate" load - the problem doesn't
   tend to show itself if you have some process that is _really_
   allocating a lot of pages, because then that process will be correctly
   found by the trashing logic. But if you have lots of "normal load"
   processes, some of those can get really badly hurt by this.
   In particular, the worst case you have a number of processes that all
   allocate memory, but not very quickly - certainly not more quickly than
   we can page things out. What happens is that under these circumstances
   one of them gets marked as a "scapegoat", and once that happens all the
   others will just live off the pages that the scapegoat frees up, while
   the scapegoat itself doesn't make much progress at all because it is
   always just freeing memory for others.
   The really bad behaviour tends to go away reasonably quickly, but while
   it happens it's _really_ unfair.
 - try_to_free_pages() just goes overboard, and starts paging stuff out
   without getting back to the nice balanced behaviour. This is what
   Andrea noticed.
   Essentially, once it starts failing the shrink_mmap() tests, it will
   just page things out crazily. Normally this is avoided by just always
   starting from shrink_mmap(), but if you ask try_to_free_pages() to try
   to free up a ton of pages, the balancing that it does is basically
   bypassed.

So basically pre-6 works _really_ well for the kind of stress-me stuff
that it was designed for: a few processes that are extremely memory
hungry. It gets close to perfect swap-out behaviour, simply because it is
optimized for getting into a paging rut.

That makes for nice benchmarks, but it also explains why (a) sometimes
it's just not very nice for interactive behaviour and (b) why it under
normal load can easily swap much too eagerly.

Anyway, the first problem is fixed by making "trashing" be a global flag
rather than a per-process flag. Being per-process is really nice when it
finds the right process, but it's really unfair under a lot of other
circumstances. I'd rather be fair than get the best possible page-out
speed.

Note that even a global flag helps: it still clusters the write-outs, and
means that processes that allocate more pages tend to be more likely to be
hit by it, so it still does a large part of what the per-process flag did
- without the unfairness (but admittedly being unfair sometimes gets you
better performance - you just have to be _very_ careful whom you target
with the unfairness, and that's the hard part).

The second problem actually goes away by simply just not asking
try_to_free_pages() to free too many pages - and having the global
trashing flag makes it unnecessary to do so anyway because the flag will
essentially cluster the page-outs even without asking for them to be all
done in one large chunk (and now it's not just one process that gets hit
any more).

There's a "pre-7.gz" on ftp.kernel.org in testing, anybody interested?
It's not the real thing, as I haven't done the write semaphore deadlock
thing yet, but that one will not affect normal users anyway so for
performance testing this should be equivalent.

                        Linus

Oh, well.. Based on what the arca-[678] patches did, there's now a pre-5
out there. Not very similar, but it should incorporate the basic idea:
namely much more aggressively asynchronous swap-outs from a process
context.
Comment away,
                Linus

Ok, you know the drill by now. This fixes:
 - yes, people told me about the new and improved ksymoops. Much better,
   no need for C++, and this one actually seems to compile and work
   reliably.
 - ntfs fixes
 - the vfat thing _really_ works now
 - NFS fix for deleting files while writebacks active.
 - ppa/imm driver updated
 - minor mm balancing patches
 - Alan took the gauntlet and cleaned up some CONFIG_PROC_FS stuff.
More on Monday,

                Linus

Well, some people obviously had problems with the first 2.2.0pre, so
there's a second one there. Most of it is almost purely syntactic sugar:
configuration issues and jiffies wraparound, but there were a few problems
wrt some IDE disk geometry stuff in particular that made 2.2.0pre1 not
boot for some people.

Other real changes:
 - nfsd updated, and we have an official maintainer for knfsd (and I was
   happy by how many people were ready to stand up for it. Good show,
   guys!)
 - network driver updates (tulip/eepro)
 - some TCP fixes for occasional but nasty performance problems.
 - fix for an attack where you could cause a complete and utter lockup of
   the kernel as a normal user. Thanks to Michael Chastain for keeping the
   faith on this one and reminding me to fix it.

If you haven't had problems with pre1, there should be no major cause to
look at pre2. But if you haven't even looked at pre1 yet, please consider
looking at the pre-2.2.0 kernels before it's too late. I'm going to be
extremely rude to people who knew better but didn't test out the pre-
kernels and then send me bug-reports on the released 2.2.0.

		Linus

 we're in the pre-2.2.0 series now, I'm all synched up with Alan, and I
don't have anything pending any more. Over the internet nobody can hear
you all scream in pain over all your favourite features that didn't make
it.

	Linus "another year older and wise as hell by now" Torvalds

There's a new pre-patch on ftp.kernel.org. I've been waiting for a few
other things, but the pre-patches are getting to be so big that it's
getting unwieldly, so I'll probably make a real 2.1.132 real soon now. In
the meantime, there's a pre-patch that people can verify for sanity (this
one should have coda-fs back to working order, for example - patch
craziness corrupted a simple update in pre-3).

                Linus

..is out there, and has everybodys favourite fix, ie the version number
has been bumped this time. In addition, compared to pre-1, it has:
 - autofs fix (uninitialized inode number could lead to "interesting"
   problems)
 - some more NFS fixes (file truncation with pending write-backs this time)
 - disable_irq()/enable_irq() now nests properly, as Alan convinced me
   (quite rightly) that they have to nest in order to work sanely with
   shared interrupt and multiple CPU's and various other schenarios.
 - more merges from Alan, we're getting closer to being synched up.
Most of the bulk of the thing is the irda stuff, that most people can
ignore.

                Linus

There's a new pre-patch out there. I'm back from Finland, and have caught
up with just about half the email that I got during the stay. However,
even the part I caught up with I may have partly missed something in,
because (for obvious reasons) I didn't read them as carefully (*) as I
usually do.

This should fix at least part of the NFS problems people have reported:
there was code to completely incorrectly invalidate quite valid write
requests under some circumstances. The pre-patch also contains the first
batch of patches merged in from Alan, and the "rmdir" problems should be
fixed (mostly thanks to Al Viro).

This pre-patch also gets rid of some imho completely unnecessary
complexity in some of the VM memory freeing routines. There have been
patches floating around that added more heuristics on when to do
something, and this tries to get the same result by just removing old
heuristics that didn't make much sense.

	Linus

(*) Even my usual "careful" is not very careful by other peoples
standards. So when _I_ say that I wasn't very careful, you should just
assume that I was reading my email about as carefully as a hyper-active
hedgehog on some serious uppers. Can you say "ignored email" three times
quickly while chewing on an apple?

2.1.131 is out there now - and will be the last kernel release for a
while. I'm going to Finland for a week and a half, and will be back mid
December. During that time I hope people will beat on this. I'll be able
to read email when I'm gone, but as I haven't been back in over a year,
I'm not very likely to.

Alan, I have got any replies (positive or negative) about the VFS fixes in
pre-2.1.131-3 (which are obviously in the real 131 too), so I hope that
means that I successfully fixed all filesystems. The chance of that being
true is remote, but hey, I can hope.  If not, I assume you'll be doing
your ac patches anyway (any bugs wrt rmdir() should be fairly obvious once
seen), and people might as well consider those official..

                Linus

Ok,
 I've made a new pre-patch-2.1.131-3.

The basic problem (that Alexander Viro correctly diagnosed) is that the
inode locking was horribly and subtly wrong for the case of a "rmdir()"
call. What rmdir() did was essentially something like

 - VFS: lock the directory that contains the directory to remove
   (this is normal and required to make sure that the name updates are
   completely atomic - so removing or adding anything requires you to hold
   the lock on the directory that contains the removee/addee)
 - low-level filesystem: lock the directory you're going to remove, in
   order to atomically check that it's empty.

So far so good, the above makes tons of sense. HOWEVER, the problem is
fairly obvious if anybody before Alexander had actually bothered to think
about it: when we hold two locks, we had better make sure that we get the
locks in the right order, or we may end up deadlocked with two (or more)
processes getting the locks in the wrong order and waiting on each other.

Now, if it was only rmdir(), things would be fine, because the directory
hierarchy itself imposes a lock order for rmdir(). But we have another
case that needs to lock two directories: "rename()". And that one doesn't
have the same kind of obvious order, and uses a different way to order the
two locks it gets. BOOM.

As far as I can tell, this is a problem in 2.0.x too, but while it's a
potential really nasty DoS-opening, it does have the saving grace that the
window to trigger it is really really small. I don't know if you can
actually make an exploit for it that has any real chance of hitting it,
but it's at least conceptually possible.

Now, the only sane fix was to actually make the VFS layer do all the
locking for rmdir(), and thus let the VFS layer make sure the order is
correct, so that low-level filesystems don't need to worry their pretty
heads. I tried to do that in the previous pre-patch, and it worked well
for ext2, but not all that much else. The problem was that too many
filesystems "knew" what the rmdir() downcall used to do. Oh, well.

Anyway, I've fixed the low-level filesystems as far as I can tell, and the
end result is a much cleaner interface (and one less bug). But it's an
interface change at a fairly late date, and while the fixes to smbfs etc
looked for the most part obvious, I haven't been able to test them, so
I've done most of them "blind".

Sadly, this bug couldn't just be glossed over, because a normal user could
(by knowing the exact right incantation) force tons of unkillable
processes that held critical filesystem resources (any lookup on a
directory that was locked would in turn also lock up). So I'd ask people
who have done filesystems for Linux to look over my changes, and if the
filesystems are not part of the standard distribution please look over
your own locally maintained fs code. I think we can ignore 2.0.x by virtue
of it probably being virtually impossible to trigger. I'll leave the
decision up to Alan.

Most specially, I'd like to have people who use/maintain vfat and umsdos
filesystems to test out that I actually made those filesystems happy with
my changes. The other filesystems were more straightforward.

Oh, and thanks to Alexander. Not that I really needed another bug to fix,
but it feels good to plug holes.

                        Linus

The change is basically:
 - the VFS layer locks the directory to be removed for you (as opposed to
   just the directory that contains the directory to be removed as it used
   to). A lot of filesystems didn't actually do this, and it is required,
   because otherwise the test for an empty directory may be subverted by a
   clever hacker.
 - the VFS layer will have done a dcache "prune" operation on the
   directory, and if there were no other uses for that dcache entry, it
   will have done a "d_drop()" on it too.
 - the above essentially means that any filesystem can do a
        if (!list_empty(&dentry->d_hash))
                return -EBUSY;
   to test whether there are other users of this directory. No need to do
   any extra pruning etc - if it's been dropped there won't be any new
   users of the dentry afterwards, so there are no races. So after doing
   the above test you know that you'll have exclusive access to the dentry
   forever.
   Most notably, the low-level filesystem should _not_ look at the
   dentry->d_count member to see how many users there are. The VFS layer
   currently artificially raises the dentry count to make sure
   "d_delete()" doesn't get rid of the inode early.
 - however: traditional local UNIX-type filesystems tend to want to allow
   removing of the directory even if it is in use by something else. This
   requires that the inode be accessible even after the rmdir() - even
   though it doesn't necessarily need to actually _do_ anything.
   For a normal UNIX-like filesystem this tends to be trivial and quite
   automatic behaviour, but you need to think about whether your
   filesystem is of the kind where the inode stays around even after the
   delete until we locally do the final "iput()". For example, on
   networked filesystems this is generally not true, simply because the
   server will have de-allocated the inode even if we still have a
   reference to it locally.

There's a pre-131-2 patch there on ftp.kernel.org in the testing
directory. This should have the NFS locking issues worked out (please
test), and also has a rather subtle but potentially very nasty deadlock
due to incorrect semaphore ordering with rmdir() hopefully fixed for good.
Alan, the regparm patches are also there.

                Linus

nfs: write back everything whenever some lock is changed (not just for
     unlock), and always invalidates the caches.

Following hot on the heels of the greased weasel, the basted turkey rears
its handsome head.

The basted turkey release fixes some problems that our dear weasel had,
namely:
 - NFS reference counting was wrong. It had been wrong for a long time,
   but apparently the more aggressively asynchronous code was more easily
   able to show the resultant random memory corruption. That should be
   gone.
 - The UP flu fixed officially (this has been in most of the 2.1.129
   patches)
 - kernel_thread() used to be able to cause bad things in init-routines at
   bootup. Fixed.
 - itimers could lead to bad things in SMP under heavy itimer load.
 - various mm tweaks to make it behave better under load. Things for dirty
   buffers still under consideration.
 - IP masqerading check fixes.
 - acenic gigabit ethernet driver
 - some drunken revelers fixed some MCA issues.
 - alpha PCI setup updates and video drivers
 - hfs and minix filesystem fixes.

On the whole, an excellent thing to do this evening, and goes together
remarkably well with some good red wine. Amaze your friends and relatives
by completely ignoring them, sitting in a corner with your own basted
turkey, and getting wasted on red wine. Much more fun than your average
thanksgiving dinner,

		Linus

There's a new pre-patch for people who want to test these things out: I'll
probably make a real 2.1.130 soon just to make sure all the silly problems
in 2.1.129 are left behind (ie the UP flu in particular that people are
still discussing even though there's a known cure).

The pre-patch fixes a rather serious problem with wall-clock itimer
functions, that admittedly was very very hard to trigger in real life (the
only reason we found it was due to the diligent help from John Taves that
saw sporadic problems under some very specific circumstances - thanks
John).

It also fixes a very silly NFS path revalidation issue: when we
revalidated a cached NFS path component, we didn't update the revalidation
time, so we ended up doing a lookup over the wire every time after the
first time - essentially making the dcache useless for path component
caching of NFS. If you use NFS heavily, you _will_ notice this change (it
also fixes some rather ugly uses of dentries and inodes in the NFS code
where we didn't update the counter so the inode wasn't guaranteed to even
be there any more!).

Also, thanks to Richard Gooch &co, who found the rather nasty race
condition when a kernel thread was started from an init-region. The
trivial fix was to not have the kernel thread function be inlined, but
while fixing it was trivial, it wasn't trivial to notice in the first
place. Good debugging.

And the UP flu is obviously fixed here (as it was in earlier pre-patches
and in various other patches floating around).

                        Linus

To a large degree is more merges for PPC and Sparc (and
somehow I must have missed ARM _again_, so I'll have to find that).

But there's a few other things in there:
 - ncr53c8xx tag fix
 - more sound fixes.
 - NFS fixed
 - some subtle TCP issues fixed
 - and lots of mm smoothness tweaks (most of those have been floating
   around for some time - like getting rid of the last vestiges of page
   ages which just complicated and hurt the code)

Have fun with it, and tell me if it breaks. But it won't. I'm finally
getting the old "greased weasel" feeling back. In short, this is the much
awaited perfect and bug-free release, and the only reason I don't call it
2.2 is that I'm chicken.

	Kvaa, kvaa,
			Linus

I don't know how I made an old pre-patch available: I've made a pre-3 that
has the proper proc thing so that it compiles (it is otherwise identical
to pre-2, so if you got pre-2 to compile by patching by hand, then there's
no reason to get pre-3).

                Linus