[PATCH v2 3/4] mm, shmem: Add shmem resident memory accounting

From: Vlastimil Babka <hidden>
Date: 2015-03-27 16:41:35
Also in: linux-mm, linux-s390, lkml
Subsystem: filesystems (vfs and infrastructure), memory management, memory management - core, memory management - oom killer, memory management - rmap (reverse mapping), memory mapping, performance events subsystem, proc filesystem, s390 architecture, the rest, uprobes · Maintainers: Alexander Viro, Christian Brauner, Andrew Morton, David Hildenbrand, Michal Hocko, Lorenzo Stoakes, Liam R. Howlett, Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds, Masami Hiramatsu, Oleg Nesterov

From: Jerome Marchand <redacted>

Currently looking at /proc/<pid>/status or statm, there is no way to
distinguish shmem pages from pages mapped to a regular file (shmem
pages are mapped to /dev/zero), even though their implication in
actual memory use is quite different.
This patch adds MM_SHMEMPAGES counter to mm_rss_stat to account for
shmem pages instead of MM_FILEPAGES.

Signed-off-by: Jerome Marchand <redacted>
Signed-off-by: Vlastimil Babka <redacted>
---
 arch/s390/mm/pgtable.c   |  5 +----
 fs/proc/task_mmu.c       |  3 ++-
 include/linux/mm.h       | 28 ++++++++++++++++++++++++++++
 include/linux/mm_types.h |  9 ++++++---
 kernel/events/uprobes.c  |  2 +-
 mm/memory.c              | 30 ++++++++++--------------------
 mm/oom_kill.c            |  5 +++--
 mm/rmap.c                | 15 ++++-----------
 8 files changed, 55 insertions(+), 42 deletions(-)

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index b2c1542..5bffd5d 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c

@@ -617,10 +617,7 @@ static void gmap_zap_swap_entry(swp_entry_t entry, struct mm_struct *mm)
 	else if (is_migration_entry(entry)) {
 		struct page *page = migration_entry_to_page(entry);
 
-		if (PageAnon(page))
-			dec_mm_counter(mm, MM_ANONPAGES);
-		else
-			dec_mm_counter(mm, MM_FILEPAGES);
+		dec_mm_counter(mm, mm_counter(page));
 	}
 	free_swap_and_cache(entry);
 }

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 1b271ec..e86e137 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c

@@ -81,7 +81,8 @@ unsigned long task_statm(struct mm_struct *mm,
 			 unsigned long *shared, unsigned long *text,
 			 unsigned long *data, unsigned long *resident)
 {
-	*shared = get_mm_counter(mm, MM_FILEPAGES);
+	*shared = get_mm_counter(mm, MM_FILEPAGES) +
+		get_mm_counter(mm, MM_SHMEMPAGES);
 	*text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
 								>> PAGE_SHIFT;
 	*data = mm->total_vm - mm->shared_vm;

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 47a9392..adfbb5b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h

@@ -1364,6 +1364,16 @@ static inline unsigned long get_mm_counter(struct mm_struct *mm, int member)
 	return (unsigned long)val;
 }
 
+/* A wrapper for the CONFIG_SHMEM dependent counter */
+static inline unsigned long get_mm_counter_shmem(struct mm_struct *mm)
+{
+#ifdef CONFIG_SHMEM
+	return get_mm_counter(mm, MM_SHMEMPAGES);
+#else
+	return 0;
+#endif
+}
+
 static inline void add_mm_counter(struct mm_struct *mm, int member, long value)
 {
 	atomic_long_add(value, &mm->rss_stat.count[member]);

@@ -1379,9 +1389,27 @@ static inline void dec_mm_counter(struct mm_struct *mm, int member)
 	atomic_long_dec(&mm->rss_stat.count[member]);
 }
 
+/* Optimized variant when page is already known not to be PageAnon */
+static inline int mm_counter_file(struct page *page)
+{
+#ifdef CONFIG_SHMEM
+	if (PageSwapBacked(page))
+		return MM_SHMEMPAGES;
+#endif
+	return MM_FILEPAGES;
+}
+
+static inline int mm_counter(struct page *page)
+{
+	if (PageAnon(page))
+		return MM_ANONPAGES;
+	return mm_counter_file(page);
+}
+
 static inline unsigned long get_mm_rss(struct mm_struct *mm)
 {
 	return get_mm_counter(mm, MM_FILEPAGES) +
+		get_mm_counter_shmem(mm) +
 		get_mm_counter(mm, MM_ANONPAGES);
 }

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 199a03a..d3c2372 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h

@@ -327,9 +327,12 @@ struct core_state {
 };
 
 enum {
-	MM_FILEPAGES,
-	MM_ANONPAGES,
-	MM_SWAPENTS,
+	MM_FILEPAGES,	/* Resident file mapping pages */
+	MM_ANONPAGES,	/* Resident anonymous pages */
+	MM_SWAPENTS,	/* Anonymous swap entries */
+#ifdef CONFIG_SHMEM
+	MM_SHMEMPAGES,	/* Resident shared memory pages */
+#endif
 	NR_MM_COUNTERS
 };

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index cb346f2..0a08fdd 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c

@@ -188,7 +188,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	lru_cache_add_active_or_unevictable(kpage, vma);
 
 	if (!PageAnon(page)) {
-		dec_mm_counter(mm, MM_FILEPAGES);
+		dec_mm_counter(mm, mm_counter_file(page));
 		inc_mm_counter(mm, MM_ANONPAGES);
 	}

diff --git a/mm/memory.c b/mm/memory.c
index 411144f..db66400 100644
--- a/mm/memory.c
+++ b/mm/memory.c

@@ -832,10 +832,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		} else if (is_migration_entry(entry)) {
 			page = migration_entry_to_page(entry);
 
-			if (PageAnon(page))
-				rss[MM_ANONPAGES]++;
-			else
-				rss[MM_FILEPAGES]++;
+			rss[mm_counter(page)]++;
 
 			if (is_write_migration_entry(entry) &&
 					is_cow_mapping(vm_flags)) {

@@ -874,10 +871,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	if (page) {
 		get_page(page);
 		page_dup_rmap(page);
-		if (PageAnon(page))
-			rss[MM_ANONPAGES]++;
-		else
-			rss[MM_FILEPAGES]++;
+		rss[mm_counter(page)]++;
 	}
 
 out_set_pte:

@@ -1113,9 +1107,8 @@ again:
 			tlb_remove_tlb_entry(tlb, pte, addr);
 			if (unlikely(!page))
 				continue;
-			if (PageAnon(page))
-				rss[MM_ANONPAGES]--;
-			else {
+
+			if (!PageAnon(page)) {
 				if (pte_dirty(ptent)) {
 					force_flush = 1;
 					set_page_dirty(page);

@@ -1123,8 +1116,8 @@ again:
 				if (pte_young(ptent) &&
 				    likely(!(vma->vm_flags & VM_SEQ_READ)))
 					mark_page_accessed(page);
-				rss[MM_FILEPAGES]--;
 			}
+			rss[mm_counter(page)]--;
 			page_remove_rmap(page);
 			if (unlikely(page_mapcount(page) < 0))
 				print_bad_pte(vma, addr, ptent, page);

@@ -1146,11 +1139,7 @@ again:
 			struct page *page;
 
 			page = migration_entry_to_page(entry);
-
-			if (PageAnon(page))
-				rss[MM_ANONPAGES]--;
-			else
-				rss[MM_FILEPAGES]--;
+			rss[mm_counter(page)]--;
 		}
 		if (unlikely(!free_swap_and_cache(entry)))
 			print_bad_pte(vma, addr, ptent, NULL);

@@ -1460,7 +1449,7 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
 
 	/* Ok, finally just insert the thing.. */
 	get_page(page);
-	inc_mm_counter_fast(mm, MM_FILEPAGES);
+	inc_mm_counter_fast(mm, mm_counter_file(page));
 	page_add_file_rmap(page);
 	set_pte_at(mm, addr, pte, mk_pte(page, prot));

@@ -2174,7 +2163,8 @@ gotten:
 	if (likely(pte_same(*page_table, orig_pte))) {
 		if (old_page) {
 			if (!PageAnon(old_page)) {
-				dec_mm_counter_fast(mm, MM_FILEPAGES);
+				dec_mm_counter_fast(mm,
+						mm_counter_file(old_page));
 				inc_mm_counter_fast(mm, MM_ANONPAGES);
 			}
 		} else

@@ -2703,7 +2693,7 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address,
 		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
 		page_add_new_anon_rmap(page, vma, address);
 	} else {
-		inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES);
+		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
 		page_add_file_rmap(page);
 	}
 	set_pte_at(vma->vm_mm, address, pte, entry);

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 642f38c..a5ee3a2 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c

@@ -573,10 +573,11 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 	/* mm cannot safely be dereferenced after task_unlock(victim) */
 	mm = victim->mm;
 	mark_tsk_oom_victim(victim);
-	pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
+	pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
 		task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
 		K(get_mm_counter(victim->mm, MM_ANONPAGES)),
-		K(get_mm_counter(victim->mm, MM_FILEPAGES)));
+		K(get_mm_counter(victim->mm, MM_FILEPAGES)),
+		K(get_mm_counter_shmem(victim->mm)));
 	task_unlock(victim);
 
 	/*

diff --git a/mm/rmap.c b/mm/rmap.c
index 5e3e090..e3c4392 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c

@@ -1216,12 +1216,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	update_hiwater_rss(mm);
 
 	if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
-		if (!PageHuge(page)) {
-			if (PageAnon(page))
-				dec_mm_counter(mm, MM_ANONPAGES);
-			else
-				dec_mm_counter(mm, MM_FILEPAGES);
-		}
+		if (!PageHuge(page))
+			dec_mm_counter(mm, mm_counter(page));
 		set_pte_at(mm, address, pte,
 			   swp_entry_to_pte(make_hwpoison_entry(page)));
 	} else if (pte_unused(pteval)) {

@@ -1230,10 +1226,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 		 * interest anymore. Simply discard the pte, vmscan
 		 * will take care of the rest.
 		 */
-		if (PageAnon(page))
-			dec_mm_counter(mm, MM_ANONPAGES);
-		else
-			dec_mm_counter(mm, MM_FILEPAGES);
+		dec_mm_counter(mm, mm_counter(page));
 	} else if (PageAnon(page)) {
 		swp_entry_t entry = { .val = page_private(page) };
 		pte_t swp_pte;

@@ -1276,7 +1269,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 		entry = make_migration_entry(page, pte_write(pteval));
 		set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
 	} else
-		dec_mm_counter(mm, MM_FILEPAGES);
+		dec_mm_counter(mm, mm_counter_file(page));
 
 	page_remove_rmap(page);
 	page_cache_release(page);

-- 
2.1.4

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