take it to mm/util.c, convert vm_mmap() to use of that one and
take it to mm/util.c as well, convert both sys_mmap_pgoff() to
use of vm_mmap_pgoff()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

just pull into vm_mmap()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

after all, 0 bytes and 0 pages is the same thing...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

it really should be done by get_unmapped_area(); that cuts down on
the amount of callers considerably and it's the right place for
that stuff anyway.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... i.e. file-dependent and address-dependent checks.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The VM accounting makes no sense at this level, and half of the callers
didn't ever actually use the end result.  The only time we want to
unaccount the memory is when we actually remove the vma, so do the
accounting at that point instead.

This simplifies the interfaces (no need to pass down that silly page
counter to functions that really don't care), and also makes it much
more obvious what is actually going on: we do vm_[un]acct_memory() when
adding or removing the vma, not on random page walking.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

None of the callers want to pass in 'zap_details', and it doesn't even
make sense for the case of actually unmapping vma's.  So remove the
argument, and clean up the interface.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

it's always current->mm
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This continues the theme started with vm_brk() and vm_munmap():
vm_mmap() does the same thing as do_mmap(), but additionally does the
required VM locking.

This uninlines (and rewrites it to be clearer) do_mmap(), which sadly
duplicates it in mm/mmap.c and mm/nommu.c.  But that way we don't have
to export our internal do_mmap_pgoff() function.

Some day we hopefully don't have to export do_mmap() either, if all
modular users can become the simpler vm_mmap() instead.  We're actually
very close to that already, with the notable exception of the (broken)
use in i810, and a couple of stragglers in binfmt_elf.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Like the vm_brk() function, this is the same as "do_munmap()", except it
does the VM locking for the caller.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It does the same thing as "do_brk()", except it handles the VM locking
too.

It turns out that all external callers want that anyway, so we can make
do_brk() static to just mm/mmap.c while at it.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Uprobes has a callback (uprobe_munmap()) in the unmap path to
maintain the uprobes count.

In the exit path this callback gets called in unlink_file_vma().
However by the time unlink_file_vma() is called, the pages would
have been unmapped (in unmap_vmas()) and the task->rss_stat counts
accounted (in zap_pte_range()).

If the exiting process has probepoints, uprobe_munmap() checks if
the breakpoint instruction was around before decrementing the probe
count.

This results in a file backed page being reread by uprobe_munmap()
and hence it does not find the breakpoint.

This patch fixes this problem by moving the callback to
unmap_single_vma(). Since unmap_single_vma() may not unmap the
complete vma, add start and end parameters to uprobe_munmap().

This bug became apparent courtesy of commit c3f0327f
("mm: add rss counters consistency check").
Signed-off-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com>
Cc: Linux-mm <linux-mm@kvack.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120411103527.23245.9835.sendpatchset@srdronam.in.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Maintain a per-mm counter: number of uprobes that are inserted
on this process address space.

This counter can be used at probe hit time to determine if we
need a lookup in the uprobes rbtree. Everytime a probe gets
inserted successfully, the probe count is incremented and
everytime a probe gets removed, the probe count is decremented.

The new uprobe_munmap hook ensures the count is correct on a
unmap or remap of a region. We expect that once a
uprobe_munmap() is called, the vma goes away.  So
uprobe_unregister() finding a probe to unregister would either
mean unmap event hasnt occurred yet or a mmap event on the same
executable file occured after a unmap event.

Additionally, uprobe_mmap hook now also gets called:

 a. on every executable vma that is COWed at fork.
 b. a vma of interest is newly mapped; breakpoint insertion also
    happens at the required address.

On process creation, make sure the probes count in the child is
set correctly.

Special cases that are taken care include:

 a. mremap
 b. VM_DONTCOPY vmas on fork()
 c. insertion/removal races in the parent during fork().
Signed-off-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com>
Cc: Linux-mm <linux-mm@kvack.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120330182646.10018.85805.sendpatchset@srdronam.in.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The comment above __insert_vm_struct seems to suggest that this function
is also going to link the VMA with the anon_vma, but this is not true.
This function only links the VMA to the mm->mm_rb tree and the mm->mmap
linked list.

[akpm@linux-foundation.org: improve comment layout and text]
Signed-off-by: NKautuk Consul <consul.kautuk@gmail.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When calling shmget() with SHM_HUGETLB, shmget aligns the request size to
PAGE_SIZE, but this is not sufficient.

Modify hugetlb_file_setup() to align requests to the huge page size, and
to accept an address argument so that all alignment checks can be
performed in hugetlb_file_setup(), rather than in its callers.  Change
newseg() and mmap_pgoff() to match the new prototype and eliminate a now
redundant alignment check.

[akpm@linux-foundation.org: fix build]
Signed-off-by: NSteven Truelove <steven.truelove@utoronto.ca>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If the required size is bigger than cached_hole_size it is better to
search from free_area_cache - it is easier to get a free region,
specifically for the 64 bit process whose address space is large enough

Do it just as hugetlb_get_unmapped_area_topdown() in arch/x86/mm/hugetlbpage.c
Signed-off-by: NXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In the current code, cached_hole_size is set to the maximum value if the
unmapped vma is less that free_area_cache so the next search will search
from the base address.

Actually, we can keep cached_hole_size so that if the next required size
is more than cached_hole_size, it can search from free_area_cache.
Signed-off-by: NXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

same story - nobody uses it and it's been pointless since
"mm: Remove i_mmap_lock lockbreak" went in.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

no point, really - the only instance that cares about those arguments of
tlb_finish_mmu() is itanic and there we explicitly check if that's called
from exit_mmap() (i.e. that ->fullmm is set), in which case we ignore those
arguments completely.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Commit 6bd4837d ("mm: simplify find_vma_prev()") broke memory
management on PA-RISC.

After application of the patch, programs that allocate big arrays on the
stack crash with segfault, for example, this will crash if compiled
without optimization:

  int main()
  {
	char array[200000];
	array[199999] = 0;
	return 0;
  }

The reason is that PA-RISC has up-growing stack and the stack is usually
the last memory area.  In the above example, a page fault happens above
the stack.

Previously, if we passed too high address to find_vma_prev, it returned
NULL and stored the last VMA in *pprev.  After "simplify find_vma_prev"
change, it stores NULL in *pprev.  Consequently, the stack area is not
found and it is not expanded, as it used to be before the change.

This patch restores the old behavior and makes it return the last VMA in
*pprev if the requested address is higher than address of any other VMA.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Acked-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently error is -ENOMEM when rejecting VM_GROWSDOWN|VM_GROWSUP
from shared anonymous: hoist the file case's -EINVAL up for both.
Signed-off-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make the uprobes code readable to me:

 - improve the Kconfig text so that a mere mortal gets some idea
   what CONFIG_UPROBES=y is really about

 - do trivial renames to standardize around the uprobes_*() namespace

 - clean up and simplify various code flow details

 - separate basic blocks of functionality

 - line break artifact and white space related removal

 - use standard local varible definition blocks

 - use vertical spacing to make things more readable

 - remove unnecessary volatile

 - restructure comment blocks to make them more uniform and
   more readable in general

Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Anton Arapov <anton@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Link: http://lkml.kernel.org/n/tip-ewbwhb8o6navvllsauu7k07p@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>

Add uprobes support to the core kernel, with x86 support.

This commit adds the kernel facilities, the actual uprobes
user-space ABI and perf probe support comes in later commits.

General design:

Uprobes are maintained in an rb-tree indexed by inode and offset
(the offset here is from the start of the mapping). For a unique
(inode, offset) tuple, there can be at most one uprobe in the
rb-tree.

Since the (inode, offset) tuple identifies a unique uprobe, more
than one user may be interested in the same uprobe. This provides
the ability to connect multiple 'consumers' to the same uprobe.

Each consumer defines a handler and a filter (optional). The
'handler' is run every time the uprobe is hit, if it matches the
'filter' criteria.

The first consumer of a uprobe causes the breakpoint to be
inserted at the specified address and subsequent consumers are
appended to this list.  On subsequent probes, the consumer gets
appended to the existing list of consumers. The breakpoint is
removed when the last consumer unregisters. For all other
unregisterations, the consumer is removed from the list of
consumers.

Given a inode, we get a list of the mms that have mapped the
inode. Do the actual registration if mm maps the page where a
probe needs to be inserted/removed.

We use a temporary list to walk through the vmas that map the
inode.

- The number of maps that map the inode, is not known before we
  walk the rmap and keeps changing.
- extending vm_area_struct wasn't recommended, it's a
  size-critical data structure.
- There can be more than one maps of the inode in the same mm.

We add callbacks to the mmap methods to keep an eye on text vmas
that are of interest to uprobes.  When a vma of interest is mapped,
we insert the breakpoint at the right address.

Uprobe works by replacing the instruction at the address defined
by (inode, offset) with the arch specific breakpoint
instruction. We save a copy of the original instruction at the
uprobed address.

This is needed for:

 a. executing the instruction out-of-line (xol).
 b. instruction analysis for any subsequent fixups.
 c. restoring the instruction back when the uprobe is unregistered.

We insert or delete a breakpoint instruction, and this
breakpoint instruction is assumed to be the smallest instruction
available on the platform. For fixed size instruction platforms
this is trivially true, for variable size instruction platforms
the breakpoint instruction is typically the smallest (often a
single byte).

Writing the instruction is done by COWing the page and changing
the instruction during the copy, this even though most platforms
allow atomic writes of the breakpoint instruction. This also
mirrors the behaviour of a ptrace() memory write to a PRIVATE
file map.

The core worker is derived from KSM's replace_page() logic.

In essence, similar to KSM:

 a. allocate a new page and copy over contents of the page that
    has the uprobed vaddr
 b. modify the copy and insert the breakpoint at the required
    address
 c. switch the original page with the copy containing the
    breakpoint
 d. flush page tables.

replace_page() is being replicated here because of some minor
changes in the type of pages and also because Hugh Dickins had
plans to improve replace_page() for KSM specific work.

Instruction analysis on x86 is based on instruction decoder and
determines if an instruction can be probed and determines the
necessary fixups after singlestep.  Instruction analysis is done
at probe insertion time so that we avoid having to repeat the
same analysis every time a probe is hit.

A lot of code here is due to the improvement/suggestions/inputs
from Peter Zijlstra.

Changelog:

(v10):
 - Add code to clear REX.B prefix as suggested by Denys Vlasenko
   and Masami Hiramatsu.

(v9):
 - Use insn_offset_modrm as suggested by Masami Hiramatsu.

(v7):

 Handle comments from Peter Zijlstra:

 - Dont take reference to inode. (expect inode to uprobe_register to be sane).
 - Use PTR_ERR to set the return value.
 - No need to take reference to inode.
 - use PTR_ERR to return error value.
 - register and uprobe_unregister share code.

(v5):

 - Modified del_consumer as per comments from Peter.
 - Drop reference to inode before dropping reference to uprobe.
 - Use i_size_read(inode) instead of inode->i_size.
 - Ensure uprobe->consumers is NULL, before __uprobe_unregister() is called.
 - Includes errno.h as recommended by Stephen Rothwell to fix a build issue
   on sparc defconfig
 - Remove restrictions while unregistering.
 - Earlier code leaked inode references under some conditions while
   registering/unregistering.
 - Continue the vma-rmap walk even if the intermediate vma doesnt
   meet the requirements.
 - Validate the vma found by find_vma before inserting/removing the
   breakpoint
 - Call del_consumer under mutex_lock.
 - Use hash locks.
 - Handle mremap.
 - Introduce find_least_offset_node() instead of close match logic in
   find_uprobe
 - Uprobes no more depends on MM_OWNER; No reference to task_structs
   while inserting/removing a probe.
 - Uses read_mapping_page instead of grab_cache_page so that the pages
   have valid content.
 - pass NULL to get_user_pages for the task parameter.
 - call SetPageUptodate on the new page allocated in write_opcode.
 - fix leaking a reference to the new page under certain conditions.
 - Include Instruction Decoder if Uprobes gets defined.
 - Remove const attributes for instruction prefix arrays.
 - Uses mm_context to know if the application is 32 bit.
Signed-off-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Also-written-by: NJim Keniston <jkenisto@us.ibm.com>
Reviewed-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Anton Arapov <anton@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linux-mm <linux-mm@kvack.org>
Link: http://lkml.kernel.org/r/20120209092642.GE16600@linux.vnet.ibm.com
[ Made various small edits to the commit log ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Trim security.h
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJames Morris <jmorris@namei.org>

Collapse security_vm_enough_memory() variants into a single function.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJames Morris <jmorris@namei.org>

commit 297c5eee ("mm: make the vma list be doubly linked") added the
vm_prev member to vm_area_struct.  We can simplify find_vma_prev() by
using it.  Also, this change helps to improve page fault performance
because it has stronger locality of reference.
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

migrate was doing an rmap_walk with speculative lock-less access on
pagetables.  That could lead it to not serializing properly against mremap
PT locks.  But a second problem remains in the order of vmas in the
same_anon_vma list used by the rmap_walk.

If vma_merge succeeds in copy_vma, the src vma could be placed after the
dst vma in the same_anon_vma list.  That could still lead to migrate
missing some pte.

This patch adds an anon_vma_moveto_tail() function to force the dst vma at
the end of the list before mremap starts to solve the problem.

If the mremap is very large and there are a lots of parents or childs
sharing the anon_vma root lock, this should still scale better than taking
the anon_vma root lock around every pte copy practically for the whole
duration of mremap.

Update: Hugh noticed special care is needed in the error path where
move_page_tables goes in the reverse direction, a second
anon_vma_moveto_tail() call is needed in the error path.

This program exercises the anon_vma_moveto_tail:

===

int main()
{
	static struct timeval oldstamp, newstamp;
	long diffsec;
	char *p, *p2, *p3, *p4;
	if (posix_memalign((void **)&p, 2*1024*1024, SIZE))
		perror("memalign"), exit(1);
	if (posix_memalign((void **)&p2, 2*1024*1024, SIZE))
		perror("memalign"), exit(1);
	if (posix_memalign((void **)&p3, 2*1024*1024, SIZE))
		perror("memalign"), exit(1);

	memset(p, 0xff, SIZE);
	printf("%p\n", p);
	memset(p2, 0xff, SIZE);
	memset(p3, 0x77, 4096);
	if (memcmp(p, p2, SIZE))
		printf("error\n");
	p4 = mremap(p+SIZE/2, SIZE/2, SIZE/2, MREMAP_FIXED|MREMAP_MAYMOVE, p3);
	if (p4 != p3)
		perror("mremap"), exit(1);
	p4 = mremap(p4, SIZE/2, SIZE/2, MREMAP_FIXED|MREMAP_MAYMOVE, p+SIZE/2);
	if (p4 != p+SIZE/2)
		perror("mremap"), exit(1);
	if (memcmp(p, p2, SIZE))
		printf("error\n");
	printf("ok\n");

	return 0;
}
===

$ perf probe -a anon_vma_moveto_tail
Add new event:
  probe:anon_vma_moveto_tail (on anon_vma_moveto_tail)

You can now use it on all perf tools, such as:

        perf record -e probe:anon_vma_moveto_tail -aR sleep 1

$ perf record -e probe:anon_vma_moveto_tail -aR ./anon_vma_moveto_tail
0x7f2ca2800000
ok
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.043 MB perf.data (~1860 samples) ]
$ perf report --stdio
   100.00%  anon_vma_moveto  [kernel.kallsyms]  [k] anon_vma_moveto_tail
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: NNai Xia <nai.xia@gmail.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pawel Sikora <pluto@agmk.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The ret variable is really not needed in mm_take_all_locks().
Signed-off-by: NKautuk Consul <consul.kautuk@gmail.com>
Reviewed-by: NMichal Hocko <mhocko@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The files changed within are only using the EXPORT_SYMBOL
macro variants.  They are not using core modular infrastructure
and hence don't need module.h but only the export.h header.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

- shmem pages are not immediately available, but they are not
  potentially available either, even if we swap them out, they will just
  relocate from memory into swap, total amount of immediate and
  potentially available memory is not going to be affected, so we
  shouldn't count them as potentially free in the first place.

- nr_free_pages() is not an expensive operation anymore, there is no
  need to split the decision making in two halves and repeat code.
Signed-off-by: NDmitry Fink <dmitry.fink@palm.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Acked-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We have some users of this function that date back to before the vma
list was doubly linked, and just are silly.  These days, you can find
the previous vma by just following the vma->vm_prev pointer.

In some cases you don't need any find_vma() lookup at all, and in other
cases you're better off with the regular "find_vma()" that uses the vma
cache front-end lookup.

Some "find_vma_prev()" users are still valid, though.  For example, in
the case of a stack that grows up, it can be the case that we don't find
any 'vma' at all (because we're looking up an address that is past the
last vma), and that the stack that we want to grow is the 'prev' vma.

But that kind of special case aside, we generally should prefer to use
'find_vma()'.

Noticed due to a totally unrelated POWER memory corruption bug that just
happened to hit in 'find_vma_prev()' and made me go "Hmm - why are we
using that function here?".
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The type of vma->vm_flags is 'unsigned long'. Neither 'int' nor
'unsigned int'. This patch fixes such misuse.
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
[ Changed to use a typedef - we'll extend it to cover more cases
  later, since there has been discussion about making it a 64-bit
  type..                      - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Straightforward conversion of anon_vma->lock to a mutex.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NHugh Dickins <hughd@google.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Straightforward conversion of i_mmap_lock to a mutex.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Hugh says:
 "The only significant loser, I think, would be page reclaim (when
  concurrent with truncation): could spin for a long time waiting for
  the i_mmap_mutex it expects would soon be dropped? "

Counter points:
 - cpu contention makes the spin stop (need_resched())
 - zap pages should be freeing pages at a higher rate than reclaim
   ever can

I think the simplification of the truncate code is definitely worth it.

Effectively reverts: 2aa15890 ("mm: prevent concurrent
unmap_mapping_range() on the same inode") and takes out the code that
caused its problem.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Rework the existing mmu_gather infrastructure.

The direct purpose of these patches was to allow preemptible mmu_gather,
but even without that I think these patches provide an improvement to the
status quo.

The first 9 patches rework the mmu_gather infrastructure.  For review
purpose I've split them into generic and per-arch patches with the last of
those a generic cleanup.

The next patch provides generic RCU page-table freeing, and the followup
is a patch converting s390 to use this.  I've also got 4 patches from
DaveM lined up (not included in this series) that uses this to implement
gup_fast() for sparc64.

Then there is one patch that extends the generic mmu_gather batching.

After that follow the mm preemptibility patches, these make part of the mm
a lot more preemptible.  It converts i_mmap_lock and anon_vma->lock to
mutexes which together with the mmu_gather rework makes mmu_gather
preemptible as well.

Making i_mmap_lock a mutex also enables a clean-up of the truncate code.

This also allows for preemptible mmu_notifiers, something that XPMEM I
think wants.

Furthermore, it removes the new and universially detested unmap_mutex.

This patch:

Remove the first obstacle towards a fully preemptible mmu_gather.

The current scheme assumes mmu_gather is always done with preemption
disabled and uses per-cpu storage for the page batches.  Change this to
try and allocate a page for batching and in case of failure, use a small
on-stack array to make some progress.

Preemptible mmu_gather is desired in general and usable once i_mmap_lock
becomes a mutex.  Doing it before the mutex conversion saves us from
having to rework the code by moving the mmu_gather bits inside the
pte_lock.

Also avoid flushing the tlb batches from under the pte lock, this is
useful even without the i_mmap_lock conversion as it significantly reduces
pte lock hold times.

[akpm@linux-foundation.org: fix comment tpyo]
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Tony Luck <tony.luck@intel.com>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NHugh Dickins <hughd@google.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently we have expand_upwards exported while expand_downwards is
accessible only via expand_stack or expand_stack_downwards.

check_stack_guard_page is a nice example of the asymmetry.  It uses
expand_stack for VM_GROWSDOWN while expand_upwards is called for
VM_GROWSUP case.

Let's clean this up by exporting both functions and make those names
consistent.  Let's use expand_{upwards,downwards} because expanding
doesn't always involve stack manipulation (an example is
ia64_do_page_fault which uses expand_upwards for registers backing store
expansion).  expand_downwards has to be defined for both
CONFIG_STACK_GROWS{UP,DOWN} because get_arg_page calls the downwards
version in the early process initialization phase for growsup
configuration.
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>