mm: convert totalram_pages and totalhigh_pages variables to atomic

totalram_pages and totalhigh_pages are made static inline function.

Main motivation was that managed_page_count_lock handling was complicating
things.  It was discussed in length here,
https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes
better to remove the lock and convert variables to atomic, with preventing
poteintial store-to-read tearing as a bonus.

[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
Suggested-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 10 insertions, 10 deletions

diff --git a/arch/csky/mm/init.c b/arch/csky/mm/init.c
index dc07c078f9b8..66e597053488 100644
--- a/arch/csky/mm/init.c
+++ b/arch/csky/mm/init.c
@@ -71,7 +71,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 		ClearPageReserved(virt_to_page(start));
 		init_page_count(virt_to_page(start));
 		free_page(start);
-		totalram_pages++;
+		totalram_pages_inc();
 	}
 }
 #endif
@@ -88,7 +88,7 @@ void free_initmem(void)
 		ClearPageReserved(virt_to_page(addr));
 		init_page_count(virt_to_page(addr));
 		free_page(addr);
-		totalram_pages++;
+		totalram_pages_inc();
 		addr += PAGE_SIZE;
 	}
 
diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index 25427a48feae..e8d63a6a9002 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -208,7 +208,7 @@ static long cmm_alloc_pages(long nr)
 
 		pa->page[pa->index++] = addr;
 		loaned_pages++;
-		totalram_pages--;
+		totalram_pages_dec();
 		spin_unlock(&cmm_lock);
 		nr--;
 	}
@@ -247,7 +247,7 @@ static long cmm_free_pages(long nr)
 		free_page(addr);
 		loaned_pages--;
 		nr--;
-		totalram_pages++;
+		totalram_pages_inc();
 	}
 	spin_unlock(&cmm_lock);
 	cmm_dbg("End request with %ld pages unfulfilled\n", nr);
@@ -291,7 +291,7 @@ static void cmm_get_mpp(void)
 	int rc;
 	struct hvcall_mpp_data mpp_data;
 	signed long active_pages_target, page_loan_request, target;
-	signed long total_pages = totalram_pages + loaned_pages;
+	signed long total_pages = totalram_pages() + loaned_pages;
 	signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;
 
 	rc = h_get_mpp(&mpp_data);
@@ -322,7 +322,7 @@ static void cmm_get_mpp(void)
 
 	cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n",
 		page_loan_request, loaned_pages, loaned_pages_target,
-		oom_freed_pages, totalram_pages);
+		oom_freed_pages, totalram_pages());
 }
 
 static struct notifier_block cmm_oom_nb = {
@@ -581,7 +581,7 @@ static int cmm_mem_going_offline(void *arg)
 			free_page(pa_curr->page[idx]);
 			freed++;
 			loaned_pages--;
-			totalram_pages++;
+			totalram_pages_inc();
 			pa_curr->page[idx] = pa_last->page[--pa_last->index];
 			if (pa_last->index == 0) {
 				if (pa_curr == pa_last)
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 76d0708438e9..50388190b393 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -59,7 +59,7 @@ static void __init setup_zero_pages(void)
 	order = 7;
 
 	/* Limit number of empty zero pages for small memory sizes */
-	while (order > 2 && (totalram_pages >> 10) < (1UL << order))
+	while (order > 2 && (totalram_pages() >> 10) < (1UL << order))
 		order--;
 
 	empty_zero_page = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 2da209687a22..8d21a83dd289 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -51,7 +51,7 @@ void __init mem_init(void)
 
 	/* this will put all low memory onto the freelists */
 	memblock_free_all();
-	max_low_pfn = totalram_pages;
+	max_low_pfn = totalram_pages();
 	max_pfn = max_low_pfn;
 	mem_init_print_info(NULL);
 	kmalloc_ok = 1;
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 168fa272cc3e..97f9ada9ceda 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -434,7 +434,7 @@ static ssize_t microcode_write(struct file *file, const char __user *buf,
 			       size_t len, loff_t *ppos)
 {
 	ssize_t ret = -EINVAL;
-	unsigned long nr_pages = totalram_pages;
+	unsigned long nr_pages = totalram_pages();
 
 	if ((len >> PAGE_SHIFT) > nr_pages) {
 		pr_err("too much data (max %ld pages)\n", nr_pages);