into home.transmeta.com:/home/torvalds/v2.5/linux

This avoids a crash that can be caused by a CLONE_DETACHED thread.

There are 4 different scenarios of late boot:

1.	no initrd or ROOT_DEV is ram0.  That's the simplest one - we want
	whatever is on ROOT_DEV as final root.

2.	initrd is there, ROOT_DEV is not ram0, /linuxrc on initrd doesn't
	exit.   We want initrd mounted, /linuxrc launched and /linuxrc
	will mount whatever it wants, maybe do pivot_root and exec init
	itself.  Task with PID 1 (parent of linuxrc) will sit there reaping
	zombies, never leaving the kernel mode.

3.	initrd is there, ROOT_DEV is not ram0, /linuxrc on initrd does exit
	and sets real-root-dev to 256 (1:0, aka. ram0).   We want initrd
	mounted, /linuxrc launched and we expect linuxrc to mount all stuff
	we need, maybe do pivot root and exit.  Parent of /linuxrc (PID 1)
	will proceed to exec init once /linuxrc is done.

4.	initrd is there, ROOT_DEV is not ram0, /linuxrc on initrd might have
	done something or not, but when it exits real-root-dev is not ram0.
	We want initrd mounted, /linuxrc launched and when it exits we are
	going to mount final root according to real-root-dev.  If there is
	/initrd on the final root, initrd will be moved there.  Otherwise
	initrd will be unmounted and its memory (if possible) freed.  Then
	we exec init from final root.

Note that we want the parent of linuxrc chrooted to initrd while linuxrc
runs - otherwise things like request_module() will be rather unhappy.  That
goes for all variants that run linuxrc.

Scenarios above go in order of increasing complexity.  Let's start with #4:

	we had loaded initrd
	we mount initrd on /root
	we open / and /old (on initrd)
	chdir /root
	mount -- move . /
	chroot .

Now we have initrd mounted on /, we are chrooted into it but keep opened
descriptors of / and /old, so we'll be able to break out of jail later.

	we fork a child that will be linuxrc
	child closes opened descriptors, opens /dev/console, dups it to stdout
and stderr, does setsid and execs /linuxrc.

	parent sits there reaping zombies until child is finished.

Note that both parent and linuxrc are chrooted into /initrd and if linuxrc
calls pivot_root, the parent will also have its root/cwd switched.

	OK, child is finished and after checking real_root_dev we see that
it's not MKDEV(1,0).  Now we know that it's scenario #4.
We break out of jail, doing the following:

	fchdir to /old on rootfs
	mount --move / .
	fchdir to / on rootfs
	chroot to .

That will move initrd to /old and leave us with root and cwd in / of rootfs.
We can close these two descriptors now - they'd done their job.

	We mount final root to /root
	We attempt to mount -- move /old /root/initrd; if we are successful -
we chdir to /root, mount --move . / and chroot to .  That will leave us with
	* final root on /
	* initrd on /initrd of final root
	* cwd and root on final root.

At that point we simply exec init.

	Now, if mount --move had failed, we got to clean up the mess.  We
unmount (with MNT_DETACH) initrd from /old and do BLKFLSBUF on ram0.  After
that we have final root on /root, initrd maybe still alive, but not mounted
anywhere and our root/cwd in / of rootfs.  Again,

	chdir /root
	mount --move . /
	chroot to .

and we have final root mounted on /, we are chrooted into it and it's time
for exec init.

	That's it for scenario 4.  The rest will be simpler - there's less
work to do.

#3 diverges from #4 after linuxrc had finished and we had already broken out
of jail.  Whatever we got from linuxrc is mounted on /old now, so we move it
back to /, get chrooted there and exec init.   We could've left earlier
(skipping the move to /old and move back parts), but that would lead to
even messier logics in prepare_namespace() ;-/

#2 means that parent of /linuxrc never gets past waiting its child to finish.
End of story.

#1 is the simplest variant - it mounts final root on /root and then does usual
"chdir there, mount --move . /, chroot to ." and execs init.

Relevant code is in prepare_namespace()/handle_initrd() and yes, it's messy.
Had been even worse... ;-/

CONFIG_M386 kernel running on PPro+ processor with X86_FEATURE_PGE may
set _PAGE_GLOBAL bit: then __flush_tlb_one must use invlpg instruction.
H. J. Lu reports (LKML 8 Sept) that his P4 reboots due to this problem.

This fixes the bootup crash.  There were two initialization bugs:

	- INIT_SIGNAL needs to set shared_pending.

	- exec() needs to set up newsig properly.

the second one caused the crash Anton saw.

This patch uses the atomic copy_from_user() facility in
generic_file_write().

This required a change in the prepare_write/commit_write API
definition.  It is no longer the case that these functions will kmap
the page for you.

If any part of the kernel wants to get at the page in the write path,
it now has to kmap it for itself.  The best way to do this is with
kmap_atomic(KM_USER0).

This patch updates all callers.  It also converts several places which
were unnecessarily using kmap() over to using kmap_atomic().

The reiserfs changes here are Oleg Drokin's revised version.

The patch has been tested with loop, ext2, ext3, reiserfs, jfs,
minixfs, vfat, iso9660, nfs and the ramdisk driver.

I haven't fixed the racy deadlock avoidance thing in
generic_file_write() - the case where we take a fault when the source
and dest of the copy are both the same pagecache page.

There is a printk in there now which will trigger if the page was
unexpectedly not present.  And guess what?  I get 50-100 of them when
running `dbench 64' on mem=48m.   This deadlock can happen.

This patch allows the kernel to hold atomic kmaps in file_read_actor().

We try to fault in the page, then take an atomic kmap.  If the atomic
copy_to_user() then faults, drop a printk and fall back to kmap().

The patch implements the atomic copy_*_user() function.

If the kernel takes a pagefault while running copy_*_user() in an
atomic region, the copy_*_user() will fail (return a short value).

And with this patch, holding an atomic kmap() puts the CPU into an
atomic region.

- Increment preempt_count() in kmap_atomic() regardless of the
  setting of CONFIG_PREEMPT.  The pagefault handler recognises this as
  an atomic region and refuses to service the fault.  copy_*_user will
  return a non-zero value.

- Attempts to propagate the in_atomic() predicate to all the other
  highmem-capable architectures' pagefault handlers.  But the code is
  only tested on x86.

- Fixed a PPC bug in kunmap_atomic(): it forgot to reenable
  preemption if HIGHMEM_DEBUG is turned on.

- Fixed a sparc bug in kunmap_atomic(): it forgot to reenable
  preemption all the time, for non-fixmap pages.

- Fix an error in <linux/highmem.h> - in the CONFIG_HIGHMEM=n case,
  kunmap_atomic() takes an address, not a page *.

Fix a problem noticed by Ed Tomlinson: under shifting workloads the
shrink_zone() logic will refill the inactive load too slowly.

Bale out of the zone scan when we've reclaimed enough pages.  Fixes a
rarely-occurring problem wherein refill_inactive_zone() ends up
shuffling 100,000 pages and generally goes silly.

This needs to be revisited - we should go on and rebalance the lower
zones even if we reclaimed enough pages from highmem.

Back out the use of preempt_count to signify atomicity wrt pagefaults.
We won't do it that way - in_atomic() works fine.

Fix the ENOSPC recovery code in __block_write_full_page()

- Don't write out clean buffers.

- Set PG_writeback before submitting the IO.  Otherwise the completion
  handler will go BUG when it sees a non-PageWriteback page.  If the IO
  is very fast, or synchronous.

Patch from Bjorn Helgaas, via Rusty.

Change:

  On node 0 totalpages: 61031         <--- not including holes
  zone(0): 65172 pages.               <--- including holes
  zone(1): 0 pages.                   ...
  zone(2): 0 pages.

to:

  On node 0 totalpages: 61031         <--- not including holes
  DMA zone: 61031 pages               <--- not including holes
  Normal zone: 0 pages
  HighMem zone: 0 pages

Support POSIX compliant thread signals on a kernel level with usable
debugging (broadcast SIGSTOP, SIGCONT) and thread group management
(broadcast SIGKILL), plus to load-balance 'process' signals between
threads for better signal performance. 

Changes:

- POSIX thread semantics for signals

there are 7 'types' of actions a signal can take: specific, load-balance,
kill-all, kill-all+core, stop-all, continue-all and ignore. Depending on
the POSIX specifications each signal has one of the types defined for both
the 'handler defined' and the 'handler not defined (kernel default)' case.  
Here is the table:

 ----------------------------------------------------------
 |                    |  userspace       |  kernel        |
 ----------------------------------------------------------
 |  SIGHUP            |  load-balance    |  kill-all      |
 |  SIGINT            |  load-balance    |  kill-all      |
 |  SIGQUIT           |  load-balance    |  kill-all+core |
 |  SIGILL            |  specific        |  kill-all+core |
 |  SIGTRAP           |  specific        |  kill-all+core |
 |  SIGABRT/SIGIOT    |  specific        |  kill-all+core |
 |  SIGBUS            |  specific        |  kill-all+core |
 |  SIGFPE            |  specific        |  kill-all+core |
 |  SIGKILL           |  n/a             |  kill-all      |
 |  SIGUSR1           |  load-balance    |  kill-all      |
 |  SIGSEGV           |  specific        |  kill-all+core |
 |  SIGUSR2           |  load-balance    |  kill-all      |
 |  SIGPIPE           |  specific        |  kill-all      |
 |  SIGALRM           |  load-balance    |  kill-all      |
 |  SIGTERM           |  load-balance    |  kill-all      |
 |  SIGCHLD           |  load-balance    |  ignore        |
 |  SIGCONT           |  load-balance    |  continue-all  |
 |  SIGSTOP           |  n/a             |  stop-all      |
 |  SIGTSTP           |  load-balance    |  stop-all      |
 |  SIGTTIN           |  load-balancen   |  stop-all      |
 |  SIGTTOU           |  load-balancen   |  stop-all      |
 |  SIGURG            |  load-balance    |  ignore        |
 |  SIGXCPU           |  specific        |  kill-all+core |
 |  SIGXFSZ           |  specific        |  kill-all+core |
 |  SIGVTALRM         |  load-balance    |  kill-all      |
 |  SIGPROF           |  specific        |  kill-all      |
 |  SIGPOLL/SIGIO     |  load-balance    |  kill-all      |
 |  SIGSYS/SIGUNUSED  |  specific        |  kill-all+core |
 |  SIGSTKFLT         |  specific        |  kill-all      |
 |  SIGWINCH          |  load-balance    |  ignore        |
 |  SIGPWR            |  load-balance    |  kill-all      |
 |  SIGRTMIN-SIGRTMAX |  load-balance    |  kill-all      |
 ----------------------------------------------------------

as you can see it from the list, signals that have handlers defined never 
get broadcasted - they are either specific or load-balanced.

- CLONE_THREAD implies CLONE_SIGHAND

It does not make much sense to have a thread group that does not share
signal handlers. In fact in the patch i'm using the signal spinlock to
lock access to the thread group. I made the siglock IRQ-safe, thus we can
load-balance signals from interrupt contexts as well. (we cannot take the
tasklist lock in write mode from IRQ handlers.)

this is not as clean as i'd like it to be, but it's the best i could come
up with so far.

- thread group list management reworked.

threads are now removed from the group if the thread is unhashed from the
PID table. This makes the most sense. This also helps with another feature 
that relies on an intact thread group list: multithreaded coredumps.

- child reparenting reworked.

the O(N) algorithm in forget_original_parent() causes massive performance
problems if a large number of threads exit from the group. Performance 
improves more than 10-fold if the following simple rules are followed 
instead:

 - reparent children to the *previous* thread [exiting or not]
 - if a thread is detached then reparent to init.

- fast broadcasting of kernel-internal SIGSTOP, SIGCONT, SIGKILL, etc.

kernel-internal broadcasted signals are a potential DoS problem, since
they might generate massive amounts of GFP_ATOMIC allocations of siginfo
structures. The important thing to note is that the siginfo structure does
not actually have to be allocated and queued - the signal processing code
has all the information it needs, neither of these signals carries any
information in the siginfo structure. This makes a broadcast SIGKILL a
very simple operation: all threads get the bit 9 set in their pending
bitmask. The speedup due to this was significant - and the robustness win
is invaluable.

- sys_execve() should not kill off 'all other' threads.

the 'exec kills all threads if the master thread does the exec()' is a
POSIX(-ish) thing that should not be hardcoded in the kernel in this case.

to handle POSIX exec() semantics, glibc uses a special syscall, which
kills 'all but self' threads: sys_exit_allbutself().

the straightforward exec() implementation just calls sys_exit_allbutself()  
and then sys_execve().

(this syscall is also be used internally if the thread group leader
thread sys_exit()s or sys_exec()s, to ensure the integrity of the thread
group.)

Added PCI_BUS_NUM_RESOURCES as Ben suggested. Default value is 4
and can be overridden by arch (probably in asm/system.h).
pci_read_bridge_bases() and pci_assign_bus_resource() changed
accordingly. "for (i = 0 ; i < 4; i++)" in pci_add_new_bus() not
changed, as it's used _only_ for pci-pci and cardbus bridges.

This patch is based on changes I've used for 2.5.31, 2.5.31-mm1,
2.5.32-mm1, 2.5.32-mm2, and 2.5.33-mm1.

Without the patch, 2.5.x during heavy benchmark/stress testing
eventually locks up with these final messages:

kernel: qlogicfc0 : no handle slots, this should not happen.
kernel: hostdata->queued is 6, in_ptr: 7d

This is a combination of Doug Ledford's patch:
http://marc.theaimsgroup.com/?l=linux-kernel&m=103005703808312&w=2
and Eric Weigle's patch:
http://marc.theaimsgroup.com/?l=linux-kernel&m=103005790509079&w=2

2.5.33 (and all predecessors i've tested) locked up without it.

but it does...

into home.transmeta.com:/home/torvalds/v2.5/linux

	* we remove the paritition 0 from ->part[] and put the old
contents of ->part[0] into gendisk itself; indexes are shifted, obviously.
	* ->part is allocated at add_gendisk() time and freed at del_gendisk()
according to value of ->minor_shift; static arrays of hd_struct are gone
from drivers, ditto for manual allocations a-la ide.  As the matter of fact,
none of the drivers know about struct hd_struct now.

	new helpers - get_capacity(gendisk)/set_capacity(gendisk, sectors).
Drivers switched to these; that eliminates most of the accesses to
disk->part[]... in the drivers (and makes code more readable, while
we are at it).  That had caught several bugs when minor had been
used in place of minor>>minor_shift (acsi.c is especially nasty in
that respect; I don't know if it had ever been used with multiple
devices...)

	 ide switched from hwif->gd[i] to hwif->drive[i]->disk - IOW, instead
of array of two pointers to gendisks refered from hwif, we keep these pointers
in relevant drives.  Cleaned up.

	SCSI cdroms got gendisks.

	invalidate_buffers() pulled from cdrom ->reset() into its caller.
At that point only cdrom.c using cdi->dev.  That will play a bit later.

	minor cleanup in cdu31a.c

	mcdx.c cleaned up, uses of cdi->dev eliminated

	 pcd.c cleaned up, uses of cdi->dev eliminated, abuse of macros killed
(it used to have
#define PCD pcd[unit]
#define PI PCD.pi
and expected 'unit' to be local variable in each function that used these
(== almost every function in there)).

	Lindent pcd.c.

	 pcd.c - killed RR and WR macros (replaced with inlines without hidden
arguments; the first step in cleanup, they were monstrous).

	sbpcd.c - d eliminated, ditto for uses of cdi->dev (we set cdi->handle
pointing to structure we neeed).  Cleaned up a bit.

	 sbpcd.[c,h] - uses of D_S[d] replaced with uses of *current_drive.

	sbpcd.c - sigh... It used to have a global variable inventively called
'd'.  Current disk number.  Tons of uses, 99% of them being D_S[d].<blah>.
Added a new variable - current_drive.  Said animal is equal to D_S + d -
it's reassigned at the same place as d.

	 killed passing minors around; we always pass a pointer to structure;
scsi_CDs made static.  That killed uses of cdi->dev in sr.c and friends.

	Global search'n'replace job - 'SCp' (Scsi_CD pointer - I'm not kidding;
and yes, they spell it "Scsi") replaced with 'cd' (sr.c, sr_ioctl.c,
sr_vendor.c).

	sr.c: we set SCp->cdi.name from the very beginning, which allows
to kill passing minors in many cases (we can use "%s...", SCp->cd.name instead
of "sr%d...", minor and that turns out to be the majority of places where
we use minors at all).

	new helper - update_partition(disk, partition_number); does the
right thing wrt devfs and driverfs (un)registration of partition entries.
BLKPG ioctls fixed - now they call that beast rather than calling only
devfs side.  New helper - rescan_partitions(disk, bdev); does all work
with wiping/rereading/etc. and fs/block_dev.c now uses it instead of
check_partition().  The latter became static.

	similar to ->flags and ->driverfs_dev_arr, ->de_arr[] got replaced
with its (single) element + flag.

	Each hd_struct used to have int number; in it.  It's used _only_
in disk->part[0] - disk->part[n].number is never assigned/checked for any
positive n.  Moved from hd_struct to gendisk (disk->part[0].number to
disk->number).

	disk->driverfs_dev_arr is either NULL or consists of exactly one
element.  Same change as above (struct device ** -> struct device *); old
"is the pointer to array itself NULL or not?" replaced with a flag (in
disk->flags).