Detach sched.h from mm.h

First thing mm.h does is including sched.h solely for can_do_mlock() inline
function which has "current" dereference inside. By dealing with can_do_mlock()
mm.h can be detached from sched.h which is good. See below, why.

This patch
a) removes unconditional inclusion of sched.h from mm.h
b) makes can_do_mlock() normal function in mm/mlock.c
c) exports can_do_mlock() to not break compilation
d) adds sched.h inclusions back to files that were getting it indirectly.
e) adds less bloated headers to some files (asm/signal.h, jiffies.h) that were
   getting them indirectly

Net result is:
a) mm.h users would get less code to open, read, preprocess, parse, ... if
   they don't need sched.h
b) sched.h stops being dependency for significant number of files:
   on x86_64 allmodconfig touching sched.h results in recompile of 4083 files,
   after patch it's only 3744 (-8.3%).

Cross-compile tested on

	all arm defconfigs, all mips defconfigs, all powerpc defconfigs,
	alpha alpha-up
	arm
	i386 i386-up i386-defconfig i386-allnoconfig
	ia64 ia64-up
	m68k
	mips
	parisc parisc-up
	powerpc powerpc-up
	s390 s390-up
	sparc sparc-up
	sparc64 sparc64-up
	um-x86_64
	x86_64 x86_64-up x86_64-defconfig x86_64-allnoconfig

as well as my two usual configs.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 15 insertions, 0 deletions

diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 1b49dab..fa360e5 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/uio.h>
 #include <linux/rmap.h>
+#include <linux/sched.h>
 #include <asm/tlbflush.h>
 #include "filemap.h"
 
diff --git a/mm/madvise.c b/mm/madvise.c
index e75096b..60542d0 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -10,6 +10,7 @@
 #include <linux/syscalls.h>
 #include <linux/mempolicy.h>
 #include <linux/hugetlb.h>
+#include <linux/sched.h>
 
 /*
  * Any behaviour which results in changes to the vma->vm_flags needs to
diff --git a/mm/mlock.c b/mm/mlock.c
index 3446b7e..4d3fea2 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -10,7 +10,18 @@
 #include <linux/mm.h>
 #include <linux/mempolicy.h>
 #include <linux/syscalls.h>
+#include <linux/sched.h>
+#include <linux/module.h>
 
+int can_do_mlock(void)
+{
+	if (capable(CAP_IPC_LOCK))
+		return 1;
+	if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0)
+		return 1;
+	return 0;
+}
+EXPORT_SYMBOL(can_do_mlock);
 
 static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
 	unsigned long start, unsigned long end, unsigned int newflags)
diff --git a/mm/msync.c b/mm/msync.c
index 358d73c..144a757 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -12,6 +12,7 @@
 #include <linux/mman.h>
 #include <linux/file.h>
 #include <linux/syscalls.h>
+#include <linux/sched.h>
 
 /*
  * MS_SYNC syncs the entire file - including mappings.
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 8faf27e..3825429 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -12,6 +12,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/cpu.h>
+#include <linux/sched.h>
 
 #ifdef CONFIG_VM_EVENT_COUNTERS
 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};