wakeups

Idle state is not being detected properly by the xfsaild push code. The
current idle state is detected by an empty list which may never happen
with mostly idle filesystem or one using lazy superblock counters. A
single dirty item in the list that exists beyond the push target can
result repeated looping attempting to push up to the target because it
fails to check if the push target has been acheived or not.

Fix by considering a dirty list with everything past the target as an idle
state and set the timeout appropriately.

SGI-PV: 977545
SGI-Modid: xfs-linux-melb:xfs-kern:30532a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

A change after 2.6.24 broke ndiswrapper by accidentally removing its
access to GPL-only symbols.  Revert that change and add comments about
the reasons why ndiswrapper and driverloader are treated in a special
way.
Signed-off-by: Pavel Roskin <proski@gnu.org>
Acked-by: Greg KH <gregkh@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jon Masters <jonathan@jonmasters.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (22 commits)
  [IPCONFIG]: The kernel gets no IP from some DHCP servers
  b43legacy: Fix module init message
  rndis_wlan: fix broken data copy
  libertas: compare the current command with response
  libertas: fix sanity check on sequence number in command response
  p54: fix eeprom parser length sanity checks
  p54: fix EEPROM structure endianness
  ssb: Add pcibios_enable_device() return value check
  rc80211-pid: fix rate adjustment
  [ESP]: Add select on AUTHENC
  [TCP]: Improve ipv4 established hash function.
  [NETPOLL]: Revert two bogus cleanups that broke netconsole.
  [PPPOL2TP]: Add missing sock_put() in pppol2tp_tunnel_closeall()
  Subject: [PPPOL2TP] add missing sock_put() in pppol2tp_recv_dequeue()
  [BLUETOOTH]: l2cap info_timer delete fix in hci_conn_del
  [NET]: Fix race in generic address resolution.
  iucv: fix build error on !SMP
  [TCP]: Must count fack_count also when skipping
  [TUN]: Fix RTNL-locking in tun/tap driver
  [SCTP]: Use proc_create to setup de->proc_fops.
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
  [SPARC]: Fix link errors with gcc-4.3
  sparc64: replace remaining __FUNCTION__ occurances
  sparc: replace remaining __FUNCTION__ occurances
  [SPARC]: Add reboot_command[] extern decl to asm/system.h
  [SPARC]: Mark linux_sparc_{fpu,chips} static.

From: Stephen Hemminger <shemminger@linux-foundation.org>

Based upon a patch by Marcel Wappler:
 
   This patch fixes a DHCP issue of the kernel: some DHCP servers
   (i.e.  in the Linksys WRT54Gv5) are very strict about the contents
   of the DHCPDISCOVER packet they receive from clients.
 
   Table 5 in RFC2131 page 36 requests the fields 'ciaddr' and
   'siaddr' MUST be set to '0'.  These DHCP servers ignore Linux
   kernel's DHCP discovery packets with these two fields set to
   '255.255.255.255' (in contrast to popular DHCP clients, such as
   'dhclient' or 'udhcpc').  This leads to a not booting system.
Signed-off-by: David S. Miller <davem@davemloft.net>

* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6:
  [IA64] fix ia64 kprobes compilation
  [IA64] move gcc_intrin.h from header-y to unifdef-y
  [IA64] workaround tiger ia64_sal_get_physical_id_info hang
  [IA64] move defconfig to arch/ia64/configs/
  [IA64] Fix irq migration in multiple vector domain
  [IA64] signal(ia64_ia32): add a signal stack overflow check
  [IA64] signal(ia64): add a signal stack overflow check
  [IA64] CONFIG_SGI_SN2 - auto select NUMA and ACPI_NUMA

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-2.6:
  debugfs: fix sparse warnings
  Driver core: Fix cleanup when failing device_add().
  driver core: Remove dpm_sysfs_remove() from error path of device_add()
  PM: fix new mutex-locking bug in the PM core
  PM: Do not acquire device semaphores upfront during suspend
  kobject: properly initialize ksets
  sysfs: CONFIG_SYSFS_DEPRECATED fix
  driver core: fix up Kconfig text for CONFIG_SYSFS_DEPRECATED

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/pci-2.6:
  pci: hotplug: pciehp: fix error code path in hpc_power_off_slot
  PCI: Add DECLARE_PCI_DEVICE_TABLE macro
  PCI: fix up error messages for pci_bus registering
  PCI: fix section mismatch warning in pci_scan_child_bus
  PCI: consolidate duplicated MSI enable functions
  PCI: use dev_printk in quirk messages

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6:
  USB: ftdi_sio - really enable EM1010PC
  USB: remove incorrect struct class_device from the printer gadget
  USB: pxa2xx_udc: fix misuse of clock enable/disable calls
  USB: ftdi_sio: Workaround for broken Matrix Orbital serial port
  USB: Add support for AXESSTEL MV110H CDMA modem
  usb-storage: update earlier scatter-gather bug fix
  USB: isp116x: fix enumeration on boot
  USB: ehci: handle large bulk URBs correctly (again)
  USB: spruce up the device blacklist
  USB: fix comment of struct usb_interface
  USB: update Kconfig entry for USB_SUSPEND
  usb: Add support for the mos7820/7840-based B&B USB/RS485 converter to mos7840.c

Fix a bug in regiseter_kretprobe() which does not check rp->kp.symbol_name ==
NULL before calling kprobe_lookup_name.

For maintainability, this introduces kprobe_addr helper function which
resolves addr field.  It is used by register_kprobe and register_kretprobe.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add to help text that the Intel I2C ICH (i801) driver is also needed
for this kernel.

Add LEDS_CLASS to config since the driver makes les_classdev_*() calls:
ERROR: "led_classdev_register" [drivers/input/misc/apanel.ko] undefined!
ERROR: "__led_classdev_unregister" [drivers/input/misc/apanel.ko]
undefined!
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The "resize" option won't be noticed as it comes after the NULL option, so if
you try to mount (or in this case remount) with that option it won't be
recognized.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Adam Litke noticed that currently we grow the hugepage pool independent of any
cpuset the running process may be in, but when shrinking the pool, the cpuset
is checked.  This leads to inconsistency when shrinking the pool in a
restricted cpuset -- an administrator may have been able to grow the pool on a
node restricted by a containing cpuset, but they cannot shrink it there.

There are two options: either prevent growing of the pool outside of the
cpuset or allow shrinking outside of the cpuset.  >From previous discussions
on linux-mm, /proc/sys/vm/nr_hugepages is an administrative interface that
should not be restricted by cpusets.  So allow shrinking the pool by removing
pages from nodes outside of current's cpuset.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Acked-by: Adam Litke <agl@us.ibm.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Lee Schermerhorn <Lee.Schermerhonr@hp.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A hugetlb reservation may be inadequately backed in the event of racing
allocations and frees when utilizing surplus huge pages.  Consider the
following series of events in processes A and B:

 A) Allocates some surplus pages to satisfy a reservation
 B) Frees some huge pages
 A) A notices the extra free pages and drops hugetlb_lock to free some of
    its surplus pages back to the buddy allocator.
 B) Allocates some huge pages
 A) Reacquires hugetlb_lock and returns from gather_surplus_huge_pages()

Avoid this by commiting the reservation after pages have been allocated but
before dropping the lock to free excess pages.  For parity, release the
reservation in return_unused_surplus_pages().

This patch also corrects the cpuset_mems_nr() error path in
hugetlb_acct_memory().  If the cpuset check fails, uncommit the
reservation, but also be sure to return any surplus huge pages that may
have been allocated to back the failed reservation.

Thanks to Andy Whitcroft for discovering this.
Signed-off-by: Adam Litke <agl@us.ibm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This message describes another issue about md RAID10 found by testing the
2.6.24 md RAID10 using new scsi fault injection framework.

Abstract:

When a scsi error results in disabling a disk during RAID10 recovery, the
resync threads of md RAID10 could stall.

This case, the raid array has already been broken and it may not matter.  But
I think stall is not preferable.  If it occurs, even shutdown or reboot will
fail because of resource busy.

The deadlock mechanism:

The r10bio_s structure has a "remaining" member to keep track of BIOs yet to
be handled when recovering.  The "remaining" counter is incremented when
building a BIO in sync_request() and is decremented when finish a BIO in
end_sync_write().

If building a BIO fails for some reasons in sync_request(), the "remaining"
should be decremented if it has already been incremented.  I found a case
where this decrement is forgotten.  This causes a md_do_sync() deadlock
because md_do_sync() waits for md_done_sync() called by end_sync_write(), but
end_sync_write() never calls md_done_sync() because of the "remaining" counter
mismatch.

For example, this problem would be reproduced in the following case:

Personalities : [raid10]
md0 : active raid10 sdf1[4] sde1[5](F) sdd1[2] sdc1[1] sdb1[6](F)
      3919616 blocks 64K chunks 2 near-copies [4/2] [_UU_]
      [>....................]  recovery =  2.2% (45376/1959808) finish=0.7min speed=45376K/sec

This case, sdf1 is recovering, sdb1 and sde1 are disabled.
An additional error with detaching sdd will cause a deadlock.

md0 : active raid10 sdf1[4] sde1[5](F) sdd1[6](F) sdc1[1] sdb1[7](F)
      3919616 blocks 64K chunks 2 near-copies [4/1] [_U__]
      [=>...................]  recovery =  5.0% (99520/1959808) finish=5.9min speed=5237K/sec

 2739 ?        S<     0:17 [md0_raid10]
28608 ?        D<     0:00 [md0_resync]
28629 pts/1    Ss     0:00 bash
28830 pts/1    R+     0:00 ps ax
31819 ?        D<     0:00 [kjournald]

The resync thread keeps working, but actually it is deadlocked.

Patch:
By this patch, the remaining counter will be decremented if needed.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Thanks to K.Tanaka and the scsi fault injection framework, here is a fix for
another possible deadlock in raid1/raid10 error handing.

If a read request returns an error while a resync is happening and a resync
request is pending, the attempt to fix the error will block until the resync
progresses, and the resync will block until the read request completes.  Thus
a deadlock.

This patch fixes the problem.

Cc: "K.Tanaka" <k-tanaka@ce.jp.nec.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This patch changes the disk to be read for layout "far > 1" to always be the
disk with the lowest block address.

Thus the chunks to be read will always be (for a fully functioning array) from
the first band of stripes, and the raid will then work as a raid0 consisting
of the first band of stripes.

Some advantages:

The fastest part which is the outer sectors of the disks involved will be
used.  The outer blocks of a disk may be as much as 100 % faster than the
inner blocks.

Average seek time will be smaller, as seeks will always be confined to the
first part of the disks.

Mixed disks with different performance characteristics will work better, as
they will work as raid0, the sequential read rate will be number of disks
involved times the IO rate of the slowest disk.

If a disk is malfunctioning, the first disk which is working, and has the
lowest block address for the logical block will be used.
Signed-off-by: Keld Simonsen <keld@dkuug.dk>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When we access attributes of an rdev (component device on an md array) through
sysfs, we really need to lock the array against concurrent changes.  We
currently do that when we change an attribute, but not when we read an
attribute.  We need to lock when reading as well else rdev->mddev could become
NULL while we are accessing it.

So add appropriate locking (mddev_lock) to rdev_attr_show.

rdev_size_store requires some extra care as well as it needs to unlock the
mddev while scanning other mddevs for overlapping regions.  We currently
assume that rdev->mddev will still be unchanged after the scan, but that
cannot be certain.  So take a copy of rdev->mddev for use at the end of the
function.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A resync/reshape/recovery thread will refuse to progress when the array is
marked read-only.  So whenever it mark it not read-only, it is important to
wake up thread resync thread.  There is one place we didn't do this.

The problem manifests if the start_ro module parameters is set, and a raid5
array that is in the middle of a reshape (restripe) is started.  The array
will initially be semi-read-only (meaning it acts like it is readonly until
the first write).  So the reshape will not proceed.

On the first write, the array will become read-write, but the reshape will not
be started, and there is no event which will ever restart that thread.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When a raid1 array is stopped, all components currently get added to the list
for auto-detection.  However we should really only add components that were
found by autodetection in the first place.  So add a flag to record that
information, and use it.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Make sure the data doesn't start before the end of the superblock when the
superblock is at the start of the device.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

On an md array with a write-intent bitmap, a thread wakes up every few seconds
and scans the bitmap looking for work to do.  If the array is idle, there will
be no work to do, but a lot of scanning is done to discover this.

So cache the fact that the bitmap is completely clean, and avoid scanning the
whole bitmap when the cache is known to be clean.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When handling a read error, we freeze the array to stop any other IO while
attempting to over-write with correct data.

This is done in the raid1d(raid10d) thread and must wait for all submitted IO
to complete (except for requests that failed and are sitting in the retry
queue - these are counted in ->nr_queue and will stay there during a freeze).

However write requests need attention from raid1d as bitmap updates might be
required.  This can cause a deadlock as raid1 is waiting for requests to
finish that themselves need attention from raid1d.

So we create a new function 'flush_pending_writes' to give that attention, and
call it in freeze_array to be sure that we aren't waiting on raid1d.

Thanks to "K.Tanaka" <k-tanaka@ce.jp.nec.com> for finding and reporting this
problem.

Cc: "K.Tanaka" <k-tanaka@ce.jp.nec.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Make PARISC's two IOMMU implementations not allocate a memory area spanning
LLD's segment boundary.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This adds struct device argument to sba_alloc_range and ccio_alloc_range, a
preparation for modifications to fix the IOMMU segment boundary problem.  This
change enables ccio_alloc_range to access to LLD's segment boundary limits.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

iommu_is_span_boundary is used internally in the IOMMU helper
(lib/iommu-helper.c), a primitive function that judges whether a memory area
spans LLD's segment boundary or not.

It's difficult to convert some IOMMUs to use the IOMMU helper but
iommu_is_span_boundary is still useful for them.  So this patch exports it.

This is needed for the parisc iommu fixes.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

After a quick glance at the code, we're getting the DEBUG_SHIRQ spurious
interrupt before we have the adapter template filled in.  Real interrupts
appear to be turned on by fcpci*_init(), so move request_irq until just before
that.
Signed-off-by: Kyle McMartin <kmcmartin@redhat.com>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When the page is not up to date, ecryptfs_prepare_write() should be
acting much like ecryptfs_readpage(). This includes the painfully
obvious step of actually decrypting the page contents read from the
lower encrypted file.

Note that this patch resolves a bug in eCryptfs in 2.6.24 that one can
produce with these steps:

# mount -t ecryptfs /secret /secret
# echo "abc" > /secret/file.txt
# umount /secret
# mount -t ecryptfs /secret /secret
# echo "def" >> /secret/file.txt
# cat /secret/file.txt

Without this patch, the resulting data returned from cat is likely to
be something other than "abc\ndef\n".

(Thanks to Benedikt Driessen for reporting this.)
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Benedikt Driessen <bdriessen@escrypt.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Last commit for unistd was not correct, it only had a partial update of
syscall numbers for __NR_timerfd_settime and __NR_timerfd_gettime.  Also,
NR_syscalls was not incremented for the new syscalls.
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Mikael Starvik <mikael.starvik@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Function __copy_user_zeroing in arch/lib/usercopy.c had the wrong parameter
set as __user, and in include/asm-cris/uaccess.h, it was not set at all for
some of the calling functions.

This will cut the number of warnings quite dramatically when using sparse.

While we're here, remove useless CVS log and correct confusing typo.
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Mikael Starvik <mikael.starvik@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I used the wrong return convention on hotkey_get_tablet_mode(), breaking a lot
of stuff.  Bad Henrique!

Fix it to return the status in the parameter-by-reference, and IO status on
the function return value.  Duh.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Zdenek Kabelac <zdenek.kabelac@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Lukas Hejtmanek <xhejtman@ics.muni.cz>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In commit e6bafba5 ("wmi: (!x & y)
strikes again"), a bug was fixed that involved converting !x & y to !(x
& y).  The code below shows the same pattern, and thus should perhaps be
fixed in the same way.

This is not tested and clearly changes the semantics, so it is only
something to consider.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@ expression E1,E2; @@
(
  !E1 & !E2
|
- !E1 & E2
+ !(E1 & E2)
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Jan Kara <jack@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In commit e6bafba5 ("wmi: (!x & y)
strikes again"), a bug was fixed that involved converting !x & y to !(x
& y).  The code below shows the same pattern, and thus should perhaps be
fixed in the same way.

This is not tested and clearly changes the semantics, so it is only
something to consider.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@ expression E1,E2; @@
(
  !E1 & !E2
|
- !E1 & E2
+ !(E1 & E2)
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In commit e6bafba5 ("wmi: (!x & y)
strikes again"), a bug was fixed that involved converting !x & y to !(x
& y).  The code below shows the same pattern, and thus should perhaps be
fixed in the same way.

This is not tested and clearly changes the semantics, so it is only
something to consider.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@ expression E1,E2; @@
(
  !E1 & !E2
|
- !E1 & E2
+ !(E1 & E2)
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In commit e6bafba5 ("wmi: (!x & y)
strikes again"), a bug was fixed that involved converting !x & y to !(x
& y).  The code below shows the same pattern, and thus should perhaps be
fixed in the same way.

This is not tested and clearly changes the semantics, so it is only
something to consider.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@ expression E1,E2; @@
(
  !E1 & !E2
|
- !E1 & E2
+ !(E1 & E2)
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

While testing force_empty, during an exit_mmap, __mem_cgroup_remove_list
called from mem_cgroup_uncharge_page oopsed on a NULL pointer in the lru list.
 I couldn't see what racing tasks on other cpus were doing, but surmise that
another must have been in mem_cgroup_charge_common on the same page, between
its unlock_page_cgroup and spin_lock_irqsave near done (thanks to that kzalloc
which I'd almost changed to a kmalloc).

Normally such a race cannot happen, the ref_cnt prevents it, the final
uncharge cannot race with the initial charge.  But force_empty buggers the
ref_cnt, that's what it's all about; and thereafter forced pages are
vulnerable to races such as this (just think of a shared page also mapped into
an mm of another mem_cgroup than that just emptied).  And remain vulnerable
until they're freed indefinitely later.

This patch just fixes the oops by moving the unlock_page_cgroups down below
adding to and removing from the list (only possible given the previous patch);
and while we're at it, we might as well make it an invariant that
page->page_cgroup is always set while pc is on lru.

But this behaviour of force_empty seems highly unsatisfactory to me: why have
a ref_cnt if we always have to cope with it being violated (as in the earlier
page migration patch).  We may prefer force_empty to move pages to an orphan
mem_cgroup (could be the root, but better not), from which other cgroups could
recover them; we might need to reverse the locking again; but no time now for
such concerns.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

As for force_empty, though this may not be the main topic here,
mem_cgroup_force_empty_list() can be implemented simpler.  It is possible to
make the function just call mem_cgroup_uncharge_page() instead of releasing
page_cgroups by itself.  The tip is to call get_page() before invoking
mem_cgroup_uncharge_page(), so the page won't be released during this
function.

Kamezawa-san points out that by the time mem_cgroup_uncharge_page() uncharges,
the page might have been reassigned to an lru of a different mem_cgroup, and
now be emptied from that; but Hugh claims that's okay, the end state is the
same as when it hasn't gone to another list.

And once force_empty stops taking lock_page_cgroup within mz->lru_lock,
mem_cgroup_move_lists() can be simplified to take mz->lru_lock directly while
holding page_cgroup lock (but still has to use try_lock_page_cgroup).
Signed-off-by: Hirokazu Takahashi <taka@valinux.co.jp>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Ever since the VM_BUG_ON(page_get_page_cgroup(page)) (now Bad page state) went
into page freeing, I've hit it from time to time in testing on some machines,
sometimes only after many days.  Recently found a machine which could usually
produce it within a few hours, which got me there at last.

The culprit is mem_cgroup_move_lists, whose locking is inadequate; and the
arrangement of structures was such that you got page_cgroups from the lru list
neatly put on to SLUB's freelist.  Kamezawa-san identified the same hole
independently.

The main problem was that it was missing the lock_page_cgroup it needs to
safely page_get_page_cgroup; but it's tricky to go beyond that too, and I
couldn't do it with SLAB_DESTROY_BY_RCU as I'd expected.  See the code for
comments on the constraints.

This patch immediately gets replaced by a simpler one from Hirokazu-san; but
is it just foolish pride that tells me to put this one on record, in case we
need to come back to it later?
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>