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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
..
caching doc: fix broken references 2011-09-27 18:08:04 +02:00
configfs configfs: convert to umode_t 2012-01-03 22:54:57 -05:00
nfs NFSD: Added fault injection documentation 2011-11-07 21:10:47 -05:00
pohmelfs Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
00-INDEX smbfs: move to drivers/staging 2010-10-05 09:08:21 -07:00
9p.txt 9p: fix 9p.txt to advertise msize instead of maxdata 2011-10-24 11:13:12 -05:00
Locking vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
Makefile Documentation/fs/: split txt and source files 2010-03-12 15:52:35 -08:00
adfs.txt adfs: add hexadecimal filetype suffix option 2011-03-22 17:44:17 -07:00
affs.txt Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
afs.txt AFS: Documentation updates 2009-08-19 10:40:13 -07:00
autofs4-mount-control.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
automount-support.txt VFS: Unexport do_kern_mount() and clean up simple_pin_fs() 2006-06-09 09:34:16 -04:00
befs.txt Documentation: befs.txt: no maintainer, orphaned 2011-08-13 18:34:03 -07:00
bfs.txt remove mention of CONFIG_KMOD from documentation 2008-07-22 19:24:29 +10:00
btrfs.txt Fix URL of btrfs-progs git repository in docs 2011-11-30 18:46:02 +01:00
ceph.txt ceph: enable/disable dentry complete flags via mount option 2012-01-12 11:00:40 -08:00
cifs.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
coda.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cramfs.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
debugfs.txt debugfs: add mode, uid and gid options 2012-01-26 11:28:49 -08:00
devpts.txt Document usage of multiple-instances of devpts 2009-01-02 10:19:36 -08:00
directory-locking Documentation: Fix up docs still talking about i_sem 2007-05-24 10:16:17 -07:00
dlmfs.txt Documentation/: it's -> its where appropriate 2010-04-23 02:09:52 +02:00
dnotify.txt Documentation/fs/: split txt and source files 2010-03-12 15:52:35 -08:00
dnotify_test.c Documentation/fs/: split txt and source files 2010-03-12 15:52:35 -08:00
ecryptfs.txt eCryptfs: Move ecryptfs docs into Documentation/filesystems/ 2007-07-17 10:23:08 -07:00
exofs.txt exofs: Add option to mount by osdname 2011-03-15 15:02:51 +02:00
ext2.txt Doc fix: ext2 can only have 32,000 subdirs, not 32,768 2009-06-18 13:03:44 -07:00
ext3.txt ext3: remove deprecated oldalloc 2011-08-17 11:42:19 +02:00
ext4.txt Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
fiemap.txt Documentation/: it's -> its where appropriate 2010-04-23 02:09:52 +02:00
files.txt fix f_count description in Documentation/filesystems/files.txt 2008-12-31 18:07:42 -05:00
fuse.txt Documentation/: it's -> its where appropriate 2010-04-23 02:09:52 +02:00
gfs2-glocks.txt GFS2: Update docs 2009-05-19 10:23:23 +01:00
gfs2-uevents.txt Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
gfs2.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
hfs.txt Documentation: HFS is orphaned 2011-11-04 12:01:48 -07:00
hfsplus.txt Documentation: document HFSPlus 2007-07-31 15:39:38 -07:00
hpfs.txt Documentation/: it's -> its where appropriate 2010-04-23 02:09:52 +02:00
inotify.txt Documentation: fix inotify source file paths 2011-11-04 12:01:47 -07:00
isofs.txt Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
jfs.txt JFS: document uid, gid, and umask mount options in jfs.txt 2007-03-09 10:27:31 -06:00
locks.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
logfs.txt fix "seperate" typos in comments 2010-05-10 11:56:30 +02:00
mandatory-locking.txt locks: add warning about mandatory locking races 2007-10-09 18:32:45 -04:00
ncpfs.txt ncpfs: remove dead URL from documentation 2009-09-23 07:39:42 -07:00
nilfs2.txt nilfs2: remove resize from unsupported features list 2011-07-13 16:08:59 +09:00
ntfs.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
ocfs2.txt ocfs2: clean up mount option about atime in ocfs2.txt 2011-05-23 23:37:12 -07:00
omfs.txt omfs: add filesystem documentation 2008-07-26 12:00:05 -07:00
path-lookup.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
porting fs: take the ACL checks to common code 2011-07-25 14:30:23 -04:00
proc.txt procfs: mark thread stack correctly in proc/<pid>/maps 2012-03-21 17:54:58 -07:00
quota.txt quota: documentation for sending "below quota" messages via netlink and tiny doc update 2008-08-12 16:07:27 -07:00
ramfs-rootfs-initramfs.txt Documentation: Fix Broken URL "freshmeat" 2012-02-21 11:43:45 +01:00
relay.txt relay: add buffer-only channels; useful for early logging 2008-07-26 12:00:04 -07:00
romfs.txt Documentation/filesystems/romfs.txt: fixing link to genromfs 2011-02-17 22:04:46 +01:00
seq_file.txt seq_file: use proc_create() in documentation 2009-12-16 07:20:07 -08:00
sharedsubtree.txt Documentation: Fix trivial typo in filesystems/sharedsubtree.txt 2010-10-25 21:18:21 -04:00
spufs.txt Fix typos in /Documentation : 'U-Z' 2006-11-30 04:58:40 +01:00
squashfs.txt Squashfs: Update documentation to include xattrs 2011-12-30 01:20:24 +00:00
sysfs-pci.txt PCI: Allow read/write access to sysfs I/O port resources 2010-07-30 09:32:08 -07:00
sysfs-tagging.txt sysfs-namespaces: add a high-level Documentation file 2010-05-21 09:37:31 -07:00
sysfs.txt sysfs: propagate umode_t 2012-01-03 22:55:03 -05:00
sysv-fs.txt [PATCH] fs/sysv/: doc cleanup 2006-12-07 08:39:44 -08:00
tmpfs.txt mempolicy: document cpuset interaction with tmpfs mpol mount option 2010-05-25 08:06:57 -07:00
ubifs.txt UBIFS: switch self-check knobs to debugfs 2011-07-04 10:54:28 +03:00
udf.txt udf: implement mode and dmode mounting options 2009-04-02 12:29:50 +02:00
ufs.txt [PATCH] ufs2 write: mount as rw 2007-02-12 09:48:40 -08:00
vfat.txt Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
vfs.txt Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
xfs-delayed-logging-design.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
xfs.txt xfs: add online discard support 2011-05-24 11:17:13 -05:00
xip.txt DOC: update xip method info 2008-11-12 17:17:17 -08:00