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A couple of /proc/vmcore data structures overflow with 32bit systems having
memory more than 4G. This patch fixes those.
Signed-off-by: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Before commit 47e65328a7b1cdfc4e3102e50d60faf94ebba7d3, next_thread() took
a const task_t. Reinstate the const qualifier, getting the next thread
never changes the current thread.
Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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We changed the wrong symbol. It's tty_insert_flip_string_flags() which is
called from the previously-non-GPL'ed now-inlined tty_insert_flip_char().
Fix that up, and uninline tty_schedule_flip() while we're there.
Cc: Tobias Powalowski <t.powa@gmx.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Lay out the structure definitions in include/linux/leds.h to be aligned as
much as possible. Also minor updates to the comments to make them more
concise.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Acked-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Implement the scheduled unexport of panic_timeout.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Ulrich suggested that the `flags' arg to sync_file_range() become unsigned.
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Some string functions were safely overrideable in lib/string.c, but their
corresponding declarations in linux/string.h were not. Correct this, and
make strcspn overrideable.
Odds of someone wanting to do optimized assembly of these are small, but
for the sake of cleanliness, might as well bring them into line with the
rest of the file.
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Current implementations define NODES_SHIFT in include/asm-xxx/numnodes.h for
each arch. Its definition is sometimes configurable. Indeed, ia64 defines 5
NODES_SHIFT values in the current git tree. But it looks a bit messy.
SGI-SN2(ia64) system requires 1024 nodes, and the number of nodes already has
been changeable by config. Suitable node's number may be changed in the
future even if it is other architecture. So, I wrote configurable node's
number.
This patch set defines just default value for each arch which needs multi
nodes except ia64. But, it is easy to change to configurable if necessary.
On ia64 the number of nodes can be already configured in generic ia64 and SN2
config. But, NODES_SHIFT is defined for DIG64 and HP'S machine too. So, I
changed it so that all platforms can be configured via CONFIG_NODES_SHIFT. It
would be simpler.
See also: http://marc.theaimsgroup.com/?l=linux-kernel&m=114358010523896&w=2
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Introduce GFP_NOWAIT, as an alias for GFP_ATOMIC & ~__GFP_HIGH.
This also changes XFS, which is the only in-tree user of this idiom that I
could find. The XFS piece is compile-tested only.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Acked-by: Nathan Scott <nathans@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add some documentation regarding the utilisation of the flags field in
struct page. This field is overloaded for per page bits and to hold node,
zone and SPARSEMEM information. Make it clear which areas are used for
what and how many bits are in each area.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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These patches are an enhancement of OVERCOMMIT_GUESS algorithm in
__vm_enough_memory().
- why the kernel needed patching
When the kernel can't allocate anonymous pages in practice, currnet
OVERCOMMIT_GUESS could return success. This implementation might be
the cause of oom kill in memory pressure situation.
If the Linux runs with page reservation features like
/proc/sys/vm/lowmem_reserve_ratio and without swap region, I think
the oom kill occurs easily.
- the overall design approach in the patch
When the OVERCOMMET_GUESS algorithm calculates number of free pages,
the reserved free pages are regarded as non-free pages.
This change helps to avoid the pitfall that the number of free pages
become less than the number which the kernel tries to keep free.
- testing results
I tested the patches using my test kernel module.
If the patches aren't applied to the kernel, __vm_enough_memory()
returns success in the situation but autual page allocation is
failed.
On the other hand, if the patches are applied to the kernel, memory
allocation failure is avoided since __vm_enough_memory() returns
failure in the situation.
I checked that on i386 SMP 16GB memory machine. I haven't tested on
nommu environment currently.
This patch adds totalreserve_pages for __vm_enough_memory().
Calculate_totalreserve_pages() checks maximum lowmem_reserve pages and
pages_high in each zone. Finally, the function stores the sum of each
zone to totalreserve_pages.
The totalreserve_pages is calculated when the VM is initilized.
And the variable is updated when /proc/sys/vm/lowmem_reserve_raito
or /proc/sys/vm/min_free_kbytes are changed.
Signed-off-by: Hideo Aoki <haoki@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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reshape_position is a 64bit field that was not 64bit aligned. So swap with
new_level.
NOTE: this is a user-visible change. However:
- The bad code has not appeared in a released kernel
- This code is still marked 'experimental'
- This only affects version-1 superblock, which are not in wide use
- These field are only used (rather than simply reported) by user-space
tools in extemely rare circumstances : after a reshape crashes in the
first second of the reshape process.
So I believe that, at this stage, the change is safe. Especially if people
heed the 'help' message on use mdadm-2.4.1.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Oleg Nesterov spotted two interesting bugs with the current de_thread
code. The simplest is a long standing double decrement of
__get_cpu_var(process_counts) in __unhash_process. Caused by
two processes exiting when only one was created.
The other is that since we no longer detach from the thread_group list
it is possible for do_each_thread when run under the tasklist_lock to
see the same task_struct twice. Once on the task list as a
thread_group_leader, and once on the thread list of another
thread.
The double appearance in do_each_thread can cause a double increment
of mm_core_waiters in zap_threads resulting in problems later on in
coredump_wait.
To remedy those two problems this patch takes the simple approach
of changing the old thread group leader into a child thread.
The only routine in release_task that cares is __unhash_process,
and it can be trivially seen that we handle cleaning up a
thread group leader properly.
Since de_thread doesn't change the pid of the exiting leader process
and instead shares it with the new leader process. I change
thread_group_leader to recognize group leadership based on the
group_leader field and not based on pids. This should also be
slightly cheaper then the existing thread_group_leader macro.
I performed a quick audit and I couldn't see any user of
thread_group_leader that cared about the difference.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Overriding the whole EH code is a per-transport, not per-host thing.
Move ->eh_strategy_handler to the transport class, same as
->eh_timed_out.
Downside is that scsi_host_alloc can't check for the total lack of EH
anymore, but the transition period from old EH where we needed it is
long gone already.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
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Rohit found an obscure bug causing buddy list corruption.
page_is_buddy is using a non-atomic test (PagePrivate && page_count == 0)
to determine whether or not a free page's buddy is itself free and in the
buddy lists.
Each of the conjuncts may be true at different times due to unrelated
conditions, so the non-atomic page_is_buddy test may find each conjunct to
be true even if they were not both true at the same time (ie. the page was
not on the buddy lists).
Signed-off-by: Martin Bligh <mbligh@google.com>
Signed-off-by: Rohit Seth <rohitseth@google.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add checksum operation which takes care of verifying the checksum and
dealing with HW checksum errors and avoids multiple checksum
operations by setting ip_summed to CHECKSUM_UNNECESSARY after
successful verification.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Change the queue rerouter intrastructure to a generic usable
infrastructure for address family specific operations as a base for
some cleanups.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Move prototypes of NAT callbacks to ip_conntrack_h323.h. Because the
use of typedefs as arguments, some header files need to be moved as
well.
Signed-off-by: Jing Min Zhao <zhaojingmin@users.sourceforge.net>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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If the HPET timer is enabled, the clock can drift by ~3 seconds a day.
This is due to the HPET timer not being initialized with the correct
setting (still using PIT count).
If HZ changes, this drift can become even more pronounced.
HPET patch initializes tick_nsec with correct tick_nsec settings for
HPET timer.
Vojtech comments:
"It's not entirely correct (it assumes the HPET ticks totally
exactly), but it's significantly better than assuming the PIT error
there."
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The node setup code would try to allocate the node metadata in the node
itself, but that fails if there is no memory in there.
This can happen with memory hotplug when the hotplug area defines an so
far empty node.
Now use bootmem to try to allocate the mem_map in other nodes.
And if it fails don't panic, but just ignore the node.
To make this work I added a new __alloc_bootmem_nopanic function that
does what its name implies.
TBD should try to use nearby nodes here. Currently we just use any.
It's hard to do it better because bootmem doesn't have proper fallback
lists yet.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Memory hotadd doesn't need SPARSEMEM, but can be handled by just preallocating
mem_maps. This only needs some untangling of ifdefs to enable the necessary
code even without SPARSEMEM.
Originally from Keith Mannthey, hacked by AK.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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* 'splice' of git://brick.kernel.dk/data/git/linux-2.6-block:
[PATCH] splice: fix page stealing LRU handling.
[PATCH] splice: page stealing needs to wait_on_page_writeback()
[PATCH] splice: export generic_splice_sendpage
[PATCH] splice: add a SPLICE_F_MORE flag
[PATCH] splice: add comments documenting more of the code
[PATCH] splice: improve writeback and clean up page stealing
[PATCH] splice: fix shadow[] filling logic
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Originally from Nick Piggin, just adapted to the newer branch.
You can't check PageLRU without holding zone->lru_lock. The page
release code can get away with it only because the page refcount is 0 at
that point. Also, you can't reliably remove pages from the LRU unless
the refcount is 0. Ever.
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Jens Axboe <axboe@suse.de>
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This lets userspace indicate whether more data will be coming in a
subsequent splice call.
Signed-off-by: Jens Axboe <axboe@suse.de>
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By cleaning up the writeback logic (killing write_one_page() and the manual
set_page_dirty()), we can get rid of ->stolen inside the pipe_buffer and
just keep it local in pipe_to_file().
This also adds dirty page balancing logic and O_SYNC handling.
Signed-off-by: Jens Axboe <axboe@suse.de>
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* git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial: (48 commits)
Documentation: fix minor kernel-doc warnings
BUG_ON() Conversion in drivers/net/
BUG_ON() Conversion in drivers/s390/net/lcs.c
BUG_ON() Conversion in mm/slab.c
BUG_ON() Conversion in mm/highmem.c
BUG_ON() Conversion in kernel/signal.c
BUG_ON() Conversion in kernel/signal.c
BUG_ON() Conversion in kernel/ptrace.c
BUG_ON() Conversion in ipc/shm.c
BUG_ON() Conversion in fs/freevxfs/
BUG_ON() Conversion in fs/udf/
BUG_ON() Conversion in fs/sysv/
BUG_ON() Conversion in fs/inode.c
BUG_ON() Conversion in fs/fcntl.c
BUG_ON() Conversion in fs/dquot.c
BUG_ON() Conversion in md/raid10.c
BUG_ON() Conversion in md/raid6main.c
BUG_ON() Conversion in md/raid5.c
Fix minor documentation typo
BFP->BPF in Documentation/networking/tuntap.txt
...
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* master.kernel.org:/pub/scm/linux/kernel/git/mchehab/v4l-dvb: (49 commits)
V4L/DVB (3667b): cpia2: fix function prototype
V4L/DVB (3702): Make msp3400 routing defines more consistent
V4L/DVB (3700): Remove obsolete commands from tvp5150.c
V4L/DVB (3697): More msp3400 and bttv fixes
V4L/DVB (3696): Previous change for cx2341X boards broke the remote support
V4L/DVB (3693): Fix msp3400c and bttv stereo/mono/bilingual detection/handling
V4L/DVB (3692): Keep experimental SLICED_VBI defines under an #if 0
V4L/DVB (3689): Kconfig: fix VP-3054 Secondary I2C Bus build configuration menu dependencies
V4L/DVB (3673): Fix budget-av CAM reset
V4L/DVB (3672): Fix memory leak in dvr open
V4L/DVB (3671): New module parameter 'tv_standard' (dvb-ttpci driver)
V4L/DVB (3670): Fix typo in comment
V4L/DVB (3669): Configurable dma buffer size for saa7146-based budget dvb cards
V4L/DVB (3653h): Move usb v4l docs into Documentation/video4linux
V4L/DVB (3667a): Fix SAP + stereo mode at msp3400
V4L/DVB (3666): Remove trailing newlines
V4L/DVB (3665): Add new NEC uPD64031A and uPD64083 i2c drivers
V4L/DVB (3663): Fix msp3400c wait time and better audio mode fallbacks
V4L/DVB (3662): Don't set msp3400c-non-existent register
V4L/DVB (3661): Add wm8739 stereo audio ADC i2c driver
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* master.kernel.org:/pub/scm/linux/kernel/git/dtor/input: (26 commits)
Input: add support for Braille devices
Input: synaptics - limit rate to 40pps on Toshiba Protege M300
Input: gamecon - add SNES mouse support
Input: make modalias code respect allowed buffer size
Input: convert /proc handling to seq_file
Input: limit attributes' output to PAGE_SIZE
Input: gameport - fix memory leak
Input: serio - fix memory leak
Input: zaurus keyboard driver updates
Input: i8042 - fix logic around pnp_register_driver()
Input: ns558 - fix logic around pnp_register_driver()
Input: pcspkr - separate device and driver registration
Input: atkbd - allow disabling on X86_PC (if EMBEDDED)
Input: atkbd - disable softrepeat for dumb keyboards
Input: atkbd - fix complaints about 'releasing unknown key 0x7f'
Input: HID - fix duplicate key mapping for Logitech UltraX remote
Input: use kzalloc() throughout the code
Input: fix input_free_device() implementation
Input: initialize serio and gameport at subsystem level
Input: uinput - semaphore to mutex conversion
...
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* master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6:
[NET]: Fully fix the memory leaks in sys_accept().
[NETFILTER]: iptables 32bit compat layer
[NETFILTER]: {ip,nf}_conntrack_netlink: fix expectation notifier unregistration
[NETFILTER]: fix ifdef for connmark support in nf_conntrack_netlink
[NETFILTER]: x_tables: unify IPv4/IPv6 multiport match
[NETFILTER]: x_tables: unify IPv4/IPv6 esp match
[NET]: Fix dentry leak in sys_accept().
[IPSEC]: Kill unused decap state structure
[IPSEC]: Kill unused decap state argument
[NET]: com90xx kmalloc fix
[TG3]: Update driver version and reldate.
[TG3]: Revert "Speed up SRAM access"
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It doesn't make the splice itself necessarily nonblocking (because the
actual file descriptors that are spliced from/to may block unless they
have the O_NONBLOCK flag set), but it makes the splice pipe operations
nonblocking.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch updates the comments to match the actual code.
Signed-off-by: Martin Waitz <tali@admingilde.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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The sliced VBI defines added in videodev2.h are removed since requires
more discussion.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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- Add KEY_BRL_* input keys and K_BRL_* keycodes;
- Add emulation of how braille keyboards usually combine braille dots
to the console keyboard driver;
- Add handling of unicode U+28xy diacritics.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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Conflicts:
arch/powerpc/kernel/setup-common.c
drivers/input/keyboard/hil_kbd.c
drivers/input/mouse/hil_ptr.c
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This patch extends current iptables compatibility layer in order to get
32bit iptables to work on 64bit kernel. Current layer is insufficient due
to alignment checks both in kernel and user space tools.
Patch is for current net-2.6.17 with addition of move of ipt_entry_{match|
target} definitions to xt_entry_{match|target}.
Signed-off-by: Dmitry Mishin <dim@openvz.org>
Acked-off-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This unifies ipt_multiport and ip6t_multiport to xt_multiport.
As a result, this addes support for inversion and port range match
to IPv6 packets.
Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This unifies ipt_esp and ip6t_esp to xt_esp. Please note that now
a user program needs to specify IPPROTO_ESP as protocol to use esp match
with IPv6. This means that ip6tables requires '-p esp' like iptables.
Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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I was grepping through the code and some `grep ganularity -R .` didn't
catch what I thought. Then looking closer I saw the term "granuality"
used in only four places (in comments) and granularity in many more
places describing the same idea. Some other facts:
dictionary.com does not know such a word
define:granuality on google is not found (and pages for granuality are
mostly related to patches to the kernel)
it has not been discussed as a term on LKML, AFAICS (=Can Search)
To be consistent, I think granularity should be used everywhere.
Signed-off-by: Kalin KOZHUHAROV <kalin@thinrope.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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* master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6:
[NET]: Allow skb headroom to be overridden
[TCP]: Kill unused extern decl for tcp_v4_hash_connecting()
[NET]: add SO_RCVBUF comment
[NET]: Deinline some larger functions from netdevice.h
[DCCP]: Use NULL for pointers, comfort sparse.
[DECNET]: Fix refcount
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As announced, lookup_hash() can now become static.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The monochrome->color expansion routine that handles bitmaps which have
(widths % 8) != 0 (slow_imageblit) produces corrupt characters in big-endian.
This is caused by a bogus bit test in slow_imageblit().
Fix.
This patch may deserve to go to the stable tree. The code has already been
well tested in little-endian machines. It's only in big-endian where there is
uncertainty and Herbert confirmed that this is the correct way to go.
It should not introduce regressions.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Acked-by: Herbert Poetzl <herbert@13thfloor.at>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Backlight class attributes are currently easy to implement incorrectly.
Moving certain handling into the backlight core prevents this whilst at the
same time makes the drivers simpler and consistent. The following changes are
included:
The brightness attribute only sets and reads the brightness variable in the
backlight_properties structure.
The power attribute only sets and reads the power variable in the
backlight_properties structure.
Any framebuffer blanking events change a variable fb_blank in the
backlight_properties structure.
The backlight driver has only two functions to implement. One function is
called when any of the above properties change (to update the backlight
brightness), the second is called to return the current backlight brightness
value. A new attribute "actual_brightness" is added to return this brightness
as determined by the driver having combined all the above factors (and any
driver/device specific factors).
Additionally, the backlight core takes care of checking the maximum brightness
is not exceeded and of turning off the backlight before device removal.
The corgi backlight driver is updated to reflect these changes.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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It is very common to hash a dentry and then to call lookup. If we take fs
specific hash functions into account the full hash logic can get ugly.
Further full_name_hash as an inline function is almost 100 bytes on x86 so
having a non-inline choice in some cases can measurably decrease code size.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Simplifies the code, reduces the need for 4 pid hash tables, and makes the
code more capable.
In the discussions I had with Oleg it was felt that to a large extent the
cleanup itself justified the work. With struct pid being dynamically
allocated meant we could create the hash table entry when the pid was
allocated and free the hash table entry when the pid was freed. Instead of
playing with the hash lists when ever a process would attach or detach to a
process.
For myself the fact that it gave what my previous task_ref patch gave for free
with simpler code was a big win. The problem is that if you hold a reference
to struct task_struct you lock in 10K of low memory. If you do that in a user
controllable way like /proc does, with an unprivileged but hostile user space
application with typical resource limits of 1000 fds and 100 processes I can
trigger the OOM killer by consuming all of low memory with task structs, on a
machine wight 1GB of low memory.
If I instead hold a reference to struct pid which holds a pointer to my
task_struct, I don't suffer from that problem because struct pid is 2 orders
of magnitude smaller. In fact struct pid is small enough that most other
kernel data structures dwarf it, so simply limiting the number of referring
data structures is enough to prevent exhaustion of low memory.
This splits the current struct pid into two structures, struct pid and struct
pid_link, and reduces our number of hash tables from PIDTYPE_MAX to just one.
struct pid_link is the per process linkage into the hash tables and lives in
struct task_struct. struct pid is given an indepedent lifetime, and holds
pointers to each of the pid types.
The independent life of struct pid simplifies attach_pid, and detach_pid,
because we are always manipulating the list of pids and not the hash table.
In addition in giving struct pid an indpendent life it makes the concept much
more powerful.
Kernel data structures can now embed a struct pid * instead of a pid_t and
not suffer from pid wrap around problems or from keeping unnecessarily
large amounts of memory allocated.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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A big problem with rcu protected data structures that are also reference
counted is that you must jump through several hoops to increase the reference
count. I think someone finally implemented atomic_inc_not_zero(&count) to
automate the common case. Unfortunately this means you must special case the
rcu access case.
When data structures are only visible via rcu in a manner that is not
determined by the reference count on the object (i.e. tasks are visible until
their zombies are reaped) there is a much simpler technique we can employ.
Simply delaying the decrement of the reference count until the rcu interval is
over.
What that means is that the proc code that looks up a task and later
wants to sleep can now do:
rcu_read_lock();
task = find_task_by_pid(some_pid);
if (task) {
get_task_struct(task);
}
rcu_read_unlock();
The effect on the rest of the kernel is that put_task_struct becomes cheaper
and immediate, and in the case where the task has been reaped it frees the
task immediate instead of unnecessarily waiting an until the rcu interval is
over.
Cleanup of task_struct does not happen when its reference count drops to
zero, instead cleanup happens when release_task is called. Tasks can only
be looked up via rcu before release_task is called. All rcu protected
members of task_struct are freed by release_task.
Therefore we can move call_rcu from put_task_struct into release_task. And
we can modify release_task to not immediately release the reference count
but instead have it call put_task_struct from the function it gives to
call_rcu.
The end result:
- get_task_struct is safe in an rcu context where we have just looked
up the task.
- put_task_struct() simplifies into its old pre rcu self.
This reorganization also makes put_task_struct uncallable from modules as
it is not exported but it does not appear to be called from any modules so
this should not be an issue, and is trivially fixed.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This just got nuked in mainline. Bring it back because Eric's patches use it.
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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To increase the strength of SCHED_BATCH as a scheduling hint we can
activate batch tasks on the expired array since by definition they are
latency insensitive tasks.
Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The activated flag in task_struct is used to track different sleep types and
its usage is somewhat obfuscated. Convert the variable to an enum with more
descriptive names without altering the function.
Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Currently, count_active_tasks() calls both nr_running() &
nr_interruptible(). Each of these functions does a "for_each_cpu" & reads
values from the runqueue of each cpu. Although this is not a lot of
instructions, each runqueue may be located on different node. Depending on
the architecture, a unique TLB entry may be required to access each
runqueue.
Since there may be more runqueues than cpu TLB entries, a scan of all
runqueues can trash the TLB. Each memory reference incurs a TLB miss &
refill.
In addition, the runqueue cacheline that contains nr_running &
nr_uninterruptible may be evicted from the cache between the two passes.
This causes unnecessary cache misses.
Combining nr_running() & nr_interruptible() into a single function
substantially reduces the TLB & cache misses on large systems. This should
have no measureable effect on smaller systems.
On a 128p IA64 system running a memory stress workload, the new function
reduced the overhead of calc_load() from 605 usec/call to 324 usec/call.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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