fs/seq_file: fallback to vmalloc allocation

There are a couple of seq_files which use the single_open() interface.
This interface requires that the whole output must fit into a single
buffer.

E.g.  for /proc/stat allocation failures have been observed because an
order-4 memory allocation failed due to memory fragmentation.  In such
situations reading /proc/stat is not possible anymore.

Therefore change the seq_file code to fallback to vmalloc allocations
which will usually result in a couple of order-0 allocations and hence
also work if memory is fragmented.

For reference a call trace where reading from /proc/stat failed:

  sadc: page allocation failure: order:4, mode:0x1040d0
  CPU: 1 PID: 192063 Comm: sadc Not tainted 3.10.0-123.el7.s390x #1
  [...]
  Call Trace:
    show_stack+0x6c/0xe8
    warn_alloc_failed+0xd6/0x138
    __alloc_pages_nodemask+0x9da/0xb68
    __get_free_pages+0x2e/0x58
    kmalloc_order_trace+0x44/0xc0
    stat_open+0x5a/0xd8
    proc_reg_open+0x8a/0x140
    do_dentry_open+0x1bc/0x2c8
    finish_open+0x46/0x60
    do_last+0x382/0x10d0
    path_openat+0xc8/0x4f8
    do_filp_open+0x46/0xa8
    do_sys_open+0x114/0x1f0
    sysc_tracego+0x14/0x1a

Conflicts:
	fs/seq_file.c

Bug: 17871993
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: David Rientjes <rientjes@google.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Thorsten Diehl <thorsten.diehl@de.ibm.com>
Cc: Andrea Righi <andrea@betterlinux.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Stefan Bader <stefan.bader@canonical.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 058504edd02667eef8fac9be27ab3ea74332e9b4
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Change-Id: Iad795a92fee1983c300568429a6283c48625bd9a
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>
fs/seq_file: Use vmalloc by default for allocations > PAGE_SIZE

Some OOM implementations are pretty trigger happy when it comes to
releasing memory for kmalloc() allocations.  We might as well head
straight to vmalloc for allocations over PAGE_SIZE.

Bug: 17871993
Change-Id: Ic0dedbadc8bf551d34cc5d77c8073938d4adef80
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>
mm, oom: make dump_tasks public

Allow other functions to dump the list of tasks.
Useful for when debugging memory leaks.

Bug: 17871993
Change-Id: I76c33a118a9765b4c2276e8c76de36399c78dbf6
Signed-off-by: Liam Mark <lmark@codeaurora.org>
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>
lowmemorykiller: make default lowmemorykiller debug message useful

lowmemorykiller debug messages are inscrutable and mostly useful
for debugging the lowmemorykiller, not explaining why a process
was killed.  Make the messages more useful by prefixing them
with "lowmemorykiller: " and explaining in more readable terms
what was killed, who it was killed for, and why it was killed.

The messages now look like:
[   76.997631] lowmemorykiller: Killing 'droid.gallery3d' (2172), adj 1000,
[   76.997635]    to free 27436kB on behalf of 'kswapd0' (29) because
[   76.997638]    cache 122624kB is below limit 122880kB for oom_score_adj 1000
[   76.997641]    Free memory is -53356kB above reserved

A negative number for free memory above reserved means some of the
reserved memory has been used and is being regenerated by kswapd,
which is likely what called the shrinkers.

Bug: 17871993
Change-Id: I1fe983381e73e124b90aa5d91cb66e55eaca390f
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>
lowmemorykiller: enhance debug information

Add extra debug information to make it easier to both determine
why the lowmemorykiller killed a process and to help find the source
of memory leaks.

Also increase the debug level for "select" statements to help prevent
flooding the log.

Bug: 17871993
Change-Id: I3b6876c5ecdf192ecc271aed3f37579f66d47a08
Signed-off-by: Liam Mark <lmark@codeaurora.org>
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>
Signed-off-by: Iliyan Malchev <malchev@google.com>
kgsl: do not vmap/memset to zero-out pages

b/18402205 External reports: Video playback failing on Flo after upgrade to
	   Lollipop

Change-Id: I358328ba2bd543d77e4218f32b0695c2f6f6e6c9
Signed-off-by: Iliyan Malchev <malchev@google.com>
Effectively revert "gpu: ion: replace __GFP_ZERO with manual zero'ing"

	commit d21375bd0e3b5c9fb1bfd341abb294349ca2507f
	Author: Mitchel Humpherys <mitchelh@codeaurora.org>
	Date:   Thu Jan 31 10:30:40 2013 -0800

	    gpu: ion: replace __GFP_ZERO with manual zero'ing

	    As a performance optimization, omit the __GFP_ZERO flag when
	    allocating individual pages and, instead, zero out all of the pages in
	    one fell swoop.

	    CRs-Fixed: 449035
	    Change-Id: Ieb9a895d8792727a8a40b1e27cb1bbeae098f581
	    Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>

b/18402205 External reports: Video playback failing on Flo after upgrade to
	   Lollipop

Change-Id: Ibd07d3ac0edd11278306d4dbe72050408cc8e09b
Signed-off-by: Iliyan Malchev <malchev@google.com>