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Siddhesh Poyarekar b76437579d procfs: mark thread stack correctly in proc/<pid>/maps 
Stack for a new thread is mapped by userspace code and passed via
sys_clone.  This memory is currently seen as anonymous in
/proc/<pid>/maps, which makes it difficult to ascertain which mappings
are being used for thread stacks.  This patch uses the individual task
stack pointers to determine which vmas are actually thread stacks.

For a multithreaded program like the following:

	#include <pthread.h>

	void *thread_main(void *foo)
	{
		while(1);
	}

	int main()
	{
		pthread_t t;
		pthread_create(&t, NULL, thread_main, NULL);
		pthread_join(t, NULL);
	}

proc/PID/maps looks like the following:

    00400000-00401000 r-xp 00000000 fd:0a 3671804                            /home/siddhesh/a.out
    00600000-00601000 rw-p 00000000 fd:0a 3671804                            /home/siddhesh/a.out
    019ef000-01a10000 rw-p 00000000 00:00 0                                  [heap]
    7f8a44491000-7f8a44492000 ---p 00000000 00:00 0
    7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0
    7f8a44c92000-7f8a44e3d000 r-xp 00000000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a44e3d000-7f8a4503d000 ---p 001ab000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a4503d000-7f8a45041000 r--p 001ab000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a45041000-7f8a45043000 rw-p 001af000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a45043000-7f8a45048000 rw-p 00000000 00:00 0
    7f8a45048000-7f8a4505f000 r-xp 00000000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4505f000-7f8a4525e000 ---p 00017000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4525e000-7f8a4525f000 r--p 00016000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4525f000-7f8a45260000 rw-p 00017000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a45260000-7f8a45264000 rw-p 00000000 00:00 0
    7f8a45264000-7f8a45286000 r-xp 00000000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45457000-7f8a4545a000 rw-p 00000000 00:00 0
    7f8a45484000-7f8a45485000 rw-p 00000000 00:00 0
    7f8a45485000-7f8a45486000 r--p 00021000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45486000-7f8a45487000 rw-p 00022000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45487000-7f8a45488000 rw-p 00000000 00:00 0
    7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0                          [stack]
    7fff627ff000-7fff62800000 r-xp 00000000 00:00 0                          [vdso]
    ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]

Here, one could guess that 7f8a44492000-7f8a44c92000 is a stack since
the earlier vma that has no permissions (7f8a44e3d000-7f8a4503d000) but
that is not always a reliable way to find out which vma is a thread
stack.  Also, /proc/PID/maps and /proc/PID/task/TID/maps has the same
content.

With this patch in place, /proc/PID/task/TID/maps are treated as 'maps
as the task would see it' and hence, only the vma that that task uses as
stack is marked as [stack].  All other 'stack' vmas are marked as
anonymous memory.  /proc/PID/maps acts as a thread group level view,
where all thread stack vmas are marked as [stack:TID] where TID is the
process ID of the task that uses that vma as stack, while the process
stack is marked as [stack].

So /proc/PID/maps will look like this:

    00400000-00401000 r-xp 00000000 fd:0a 3671804                            /home/siddhesh/a.out
    00600000-00601000 rw-p 00000000 fd:0a 3671804                            /home/siddhesh/a.out
    019ef000-01a10000 rw-p 00000000 00:00 0                                  [heap]
    7f8a44491000-7f8a44492000 ---p 00000000 00:00 0
    7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0                          [stack:1442]
    7f8a44c92000-7f8a44e3d000 r-xp 00000000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a44e3d000-7f8a4503d000 ---p 001ab000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a4503d000-7f8a45041000 r--p 001ab000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a45041000-7f8a45043000 rw-p 001af000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a45043000-7f8a45048000 rw-p 00000000 00:00 0
    7f8a45048000-7f8a4505f000 r-xp 00000000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4505f000-7f8a4525e000 ---p 00017000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4525e000-7f8a4525f000 r--p 00016000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4525f000-7f8a45260000 rw-p 00017000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a45260000-7f8a45264000 rw-p 00000000 00:00 0
    7f8a45264000-7f8a45286000 r-xp 00000000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45457000-7f8a4545a000 rw-p 00000000 00:00 0
    7f8a45484000-7f8a45485000 rw-p 00000000 00:00 0
    7f8a45485000-7f8a45486000 r--p 00021000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45486000-7f8a45487000 rw-p 00022000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45487000-7f8a45488000 rw-p 00000000 00:00 0
    7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0                          [stack]
    7fff627ff000-7fff62800000 r-xp 00000000 00:00 0                          [vdso]
    ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]

Thus marking all vmas that are used as stacks by the threads in the
thread group along with the process stack.  The task level maps will
however like this:

    00400000-00401000 r-xp 00000000 fd:0a 3671804                            /home/siddhesh/a.out
    00600000-00601000 rw-p 00000000 fd:0a 3671804                            /home/siddhesh/a.out
    019ef000-01a10000 rw-p 00000000 00:00 0                                  [heap]
    7f8a44491000-7f8a44492000 ---p 00000000 00:00 0
    7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0                          [stack]
    7f8a44c92000-7f8a44e3d000 r-xp 00000000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a44e3d000-7f8a4503d000 ---p 001ab000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a4503d000-7f8a45041000 r--p 001ab000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a45041000-7f8a45043000 rw-p 001af000 fd:00 2097482                    /lib64/libc-2.14.90.so
    7f8a45043000-7f8a45048000 rw-p 00000000 00:00 0
    7f8a45048000-7f8a4505f000 r-xp 00000000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4505f000-7f8a4525e000 ---p 00017000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4525e000-7f8a4525f000 r--p 00016000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a4525f000-7f8a45260000 rw-p 00017000 fd:00 2099938                    /lib64/libpthread-2.14.90.so
    7f8a45260000-7f8a45264000 rw-p 00000000 00:00 0
    7f8a45264000-7f8a45286000 r-xp 00000000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45457000-7f8a4545a000 rw-p 00000000 00:00 0
    7f8a45484000-7f8a45485000 rw-p 00000000 00:00 0
    7f8a45485000-7f8a45486000 r--p 00021000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45486000-7f8a45487000 rw-p 00022000 fd:00 2097348                    /lib64/ld-2.14.90.so
    7f8a45487000-7f8a45488000 rw-p 00000000 00:00 0
    7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0
    7fff627ff000-7fff62800000 r-xp 00000000 00:00 0                          [vdso]
    ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]

where only the vma that is being used as a stack by *that* task is
marked as [stack].

Analogous changes have been made to /proc/PID/smaps,
/proc/PID/numa_maps, /proc/PID/task/TID/smaps and
/proc/PID/task/TID/numa_maps. Relevant snippets from smaps and
numa_maps:

    [siddhesh@localhost ~ ]$ pgrep a.out
    1441
    [siddhesh@localhost ~ ]$ cat /proc/1441/smaps | grep "\[stack"
    7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0                          [stack:1442]
    7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0                          [stack]
    [siddhesh@localhost ~ ]$ cat /proc/1441/task/1442/smaps | grep "\[stack"
    7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0                          [stack]
    [siddhesh@localhost ~ ]$ cat /proc/1441/task/1441/smaps | grep "\[stack"
    7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0                          [stack]
    [siddhesh@localhost ~ ]$ cat /proc/1441/numa_maps | grep "stack"
    7f8a44492000 default stack:1442 anon=2 dirty=2 N0=2
    7fff6273a000 default stack anon=3 dirty=3 N0=3
    [siddhesh@localhost ~ ]$ cat /proc/1441/task/1442/numa_maps | grep "stack"
    7f8a44492000 default stack anon=2 dirty=2 N0=2
    [siddhesh@localhost ~ ]$ cat /proc/1441/task/1441/numa_maps | grep "stack"
    7fff6273a000 default stack anon=3 dirty=3 N0=3

[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix build]
Signed-off-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jamie Lokier <jamie@shareable.org>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2012-03-21 17:54:58 -07:00
..
ABI Power management updates for 3.4 2012-03-21 10:15:51 -07:00
DocBook Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-03-20 21:12:50 -07:00
PCI doc: fix broken references 2011-09-27 18:08:04 +02:00
RCU rcu: Call out dangers of expedited RCU primitives 2012-02-21 09:06:08 -08:00
accounting
…
acpi acpi/apei/einj: Add extensions to EINJ from rev 5.0 of acpi spec 2012-01-18 01:14:17 -05:00
aoe
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arm Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
auxdisplay
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blackfin doc: fix broken references 2011-09-27 18:08:04 +02:00
block Documentation: drop as block elevator reference in switching-sched.txt 2011-11-04 12:01:48 -07:00
blockdev cciss: auto engage SCSI mid layer at driver load time 2011-11-16 09:21:49 +01:00
cdrom doc: fix broken references 2011-09-27 18:08:04 +02:00
cgroups Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-03-20 21:12:50 -07:00
connector
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console
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cpu-freq Doc: cpufreq: Fix typo and outdated line 2011-11-08 10:23:29 +01:00
cpuidle
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cris
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crypto
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development-process Documentation: Update stable address 2011-12-12 14:14:31 -08:00
device-mapper Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
devicetree regulator: Updates for 3.4 2012-03-21 10:34:56 -07:00
driver-model Merge remote-tracking branches 'regulator/topic/devm' and 'regulator/topic/stub' into regulator-next 2012-03-18 21:38:28 +00:00
dvb [media] dvb_get_firmware: updates for it913x 2011-12-11 09:00:48 -02:00
early-userspace
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fault-injection fault-injection: update documentation with the mmc module param 2011-10-26 16:32:13 -04:00
fb Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
filesystems procfs: mark thread stack correctly in proc/<pid>/maps 2012-03-21 17:54:58 -07:00
firmware_class
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frv doc: fix broken references 2011-09-27 18:08:04 +02:00
hid
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hwmon hwmon changes for v3.4 2012-03-21 10:37:25 -07:00
i2c USB: ohci-nxp: Rename symbols from pnx4008 to nxp 2012-03-13 14:27:28 -07:00
i2o Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
ia64
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ide Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
infiniband
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input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-03-20 21:12:50 -07:00
ioctl Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-03-20 21:12:50 -07:00
isdn
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ja_JP
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kbuild Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
kdump [S390] Add s390x description to Documentation/kdump/kdump.txt 2011-12-27 11:27:13 +01:00
ko_KR driver-core: documentation: fix up Greg's email address 2012-02-15 14:48:01 -08:00
laptops Documentation: thinkpad-acpi grammo fixes 2011-11-04 12:01:47 -07:00
leds Documentation: fix leds-class.txt duplicated word 2011-11-04 12:01:48 -07:00
m68k
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make
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mips
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misc-devices
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mmc mmc: core: Fixup delayed work clock gating patch 2012-01-11 23:58:43 -05:00
mn10300
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mtd
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namespaces
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netlabel
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networking Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-03-20 21:12:50 -07:00
nfc
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parisc
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pcmcia
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power PM / Freezer / Docs: Document the beauty of freeze/thaw semantics 2012-02-09 23:55:49 +01:00
powerpc
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pps
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prctl
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pti
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ptp
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rapidio RapidIO: documentation update 2011-11-02 16:07:02 -07:00
s390 [S390] Remove Kerntypes leftovers 2011-12-27 11:27:12 +01:00
scheduler sched: Remove sched_switch 2012-01-27 13:28:53 +01:00
scsi Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
security Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
serial serial/documentation: fix documented name of DCD cpp symbol 2012-01-04 16:26:32 -08:00
sh
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sound Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
sparc
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spi spi: create a message queueing infrastructure 2012-03-07 19:19:48 -07:00
sysctl Documentation: add missing tainted bits to Documentation/sysctl/kernel.txt 2012-02-06 16:29:19 -08:00
target Documentation: Fix typo in tcm_mod_builder.py 2012-02-10 09:52:18 +01:00
telephony
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thermal thermal: Rename generate_netlink_event 2012-01-23 03:15:25 -05:00
timers doc: fix broken references 2011-09-27 18:08:04 +02:00
trace Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-03-20 21:12:50 -07:00
usb Documentation: Fix Broken URL "freshmeat" 2012-02-21 11:43:45 +01:00
vDSO
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video4linux Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
virtual Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
vm pagemap: document KPF_THP and make page-types aware of it 2012-03-21 17:54:57 -07:00
w1
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watchdog Documentation: Fix typo in watchdog-kernel-api.txt 2012-02-21 11:40:34 +01:00
wimax
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x86
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zh_CN Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-03-20 21:04:47 -07:00
.gitignore
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00-INDEX Documentation: Fix broken URL "JF" 2012-02-21 11:44:14 +01:00
BUG-HUNTING
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Changes
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CodingStyle Documentation: update CodingStyle use of braces 2011-11-04 12:01:47 -07:00
DMA-API-HOWTO.txt
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DMA-API.txt include/linux/dma-mapping.h: add dma_zalloc_coherent() 2011-11-02 16:07:02 -07:00
DMA-ISA-LPC.txt
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DMA-attributes.txt
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HOWTO Documentation: Update stable address 2011-12-12 14:14:31 -08:00
IPMI.txt
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IRQ-affinity.txt
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IRQ-domain.txt irq_domain: add documentation and MAINTAINERS entry. 2012-02-14 14:06:47 -07:00
IRQ.txt
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Intel-IOMMU.txt
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Makefile
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ManagementStyle
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SAK.txt
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SM501.txt
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SecurityBugs
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SubmitChecklist
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SubmittingDrivers
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SubmittingPatches
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VGA-softcursor.txt
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applying-patches.txt
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atomic_ops.txt doc: Add load/store guarantees to Documentation/atomic-ops.txt 2011-12-11 10:31:58 -08:00
bad_memory.txt
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basic_profiling.txt
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binfmt_misc.txt
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braille-console.txt
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bt8xxgpio.txt
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btmrvl.txt
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bus-virt-phys-mapping.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
cachetlb.txt
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circular-buffers.txt
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coccinelle.txt coccinelle.txt: update documentation to include M= option 2012-01-14 22:25:56 +01:00
cpu-hotplug.txt
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cpu-load.txt
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cputopology.txt
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dcdbas.txt
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debugging-modules.txt
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debugging-via-ohci1394.txt
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dell_rbu.txt
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devices.txt vhost-net: add module alias (v2.1) 2012-01-13 10:12:23 -08:00
digsig.txt crypto: digital signature verification support 2011-11-09 12:10:37 +02:00
dma-buf-sharing.txt dma-buf: Documentation update for Kconfig select 2012-01-13 10:27:33 +00:00
dmaengine.txt Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
dontdiff [S390] Remove Kerntypes leftovers 2011-12-27 11:27:12 +01:00
dynamic-debug-howto.txt dynamic_debug: process multiple debug-queries on a line 2012-01-24 12:50:36 -08:00
edac.txt
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eisa.txt
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email-clients.txt
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feature-removal-schedule.txt Merge branch 'kmap_atomic' of git://github.com/congwang/linux 2012-03-21 09:40:26 -07:00
flexible-arrays.txt
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futex-requeue-pi.txt
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gcov.txt
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gpio.txt
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highuid.txt
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hw_random.txt
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hwspinlock.txt hwspinlock/core: register a bank of hwspinlocks in a single API call 2011-09-21 19:45:34 +03:00
init.txt
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initrd.txt
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intel_txt.txt
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io-mapping.txt
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io_ordering.txt
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iostats.txt
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irqflags-tracing.txt
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isapnp.txt
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java.txt
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kernel-doc-nano-HOWTO.txt
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kernel-docs.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
kernel-parameters.txt thp: documentation: 'transparent_hugepage=' can also be specified on cmdline 2012-03-21 17:54:57 -07:00
kmemcheck.txt
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kmemleak.txt kmemleak: Handle percpu memory allocation 2011-12-02 16:12:42 +00:00
kobject.txt driver-core: documentation: fix up Greg's email address 2012-02-15 14:48:01 -08:00
kprobes.txt
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kref.txt
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ldm.txt
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local_ops.txt
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lockdep-design.txt lockdep: Update documentation for lock-class leak detection 2011-12-11 10:31:23 -08:00
lockstat.txt
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lockup-watchdogs.txt watchdog: Update documentation 2012-02-11 15:11:28 +01:00
logo.gif
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logo.txt
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magic-number.txt drivers/net: fix up stale paths from driver reorg 2012-01-30 12:54:40 -05:00
mca.txt
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md.txt md: create externally visible flags for supporting hot-replace. 2011-12-23 10:17:51 +11:00
media-framework.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
memory-barriers.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
memory-hotplug.txt
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memory.txt
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mono.txt
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mutex-design.txt
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nommu-mmap.txt
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numastat.txt Doc: Update numastat.txt 2012-02-28 16:05:06 +01:00
oops-tracing.txt module,bug: Add TAINT_OOT_MODULE flag for modules not built in-tree 2011-11-07 07:54:42 +10:30
padata.txt
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parport-lowlevel.txt
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parport.txt
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pi-futex.txt
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pinctrl.txt pinctrl: fix some pinmux typos 2012-01-26 14:11:31 +01:00
pnp.txt
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preempt-locking.txt
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printk-formats.txt
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prio_tree.txt
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ramoops.txt
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rbtree.txt
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rfkill.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
robust-futex-ABI.txt
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robust-futexes.txt
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rt-mutex-design.txt
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rt-mutex.txt
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rtc.txt
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serial-console.txt
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sgi-ioc4.txt
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sgi-visws.txt
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sparse.txt
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spinlocks.txt
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stable_api_nonsense.txt
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stable_kernel_rules.txt stable: update documentation to ask for kernel version 2012-01-24 10:50:22 -08:00
static-keys.txt static keys: Add docs better explaining the whole 'struct static_key' mechanism 2012-02-24 09:12:19 +01:00
svga.txt
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sysfs-rules.txt
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sysrq.txt
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unaligned-memory-access.txt
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unicode.txt
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unshare.txt
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vgaarbiter.txt misc latin1 to utf8 conversions 2012-01-02 13:04:55 +01:00
video-output.txt
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volatile-considered-harmful.txt
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workqueue.txt
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xz.txt
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zorro.txt
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