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Commit eca56ff9 authored by Jerome Marchand's avatar Jerome Marchand Committed by Linus Torvalds
Browse files

mm, shmem: add internal shmem resident memory accounting 



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.

The internal accounting currently counts shmem pages together with
regular files.  As a preparation to extend the userspace interfaces,
this patch adds MM_SHMEMPAGES counter to mm_rss_stat to account for
shmem pages separately from MM_FILEPAGES.  The next patch will expose it
to userspace - this patch doesn't change the exported values yet, by
adding up MM_SHMEMPAGES to MM_FILEPAGES at places where MM_FILEPAGES was
used before.  The only user-visible change after this patch is the OOM
killer message that separates the reported "shmem-rss" from "file-rss".

[vbabka@suse.cz: forward-porting, tweak changelog]
Signed-off-by: default avatarJerome Marchand <jmarchan@redhat.com>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 48131e03

arch/s390/mm/pgtable.c

+1 −4
Original line number Diff line number Diff line
@@ -603,10 +603,7 @@ 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);

}

fs/proc/task_mmu.c

+2 −1
Original line number Diff line number Diff line
@@ -83,7 +83,8 @@ 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;

include/linux/mm.h

+17 −1
Original line number Diff line number Diff line
@@ -1361,10 +1361,26 @@ 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)

{

	if (PageSwapBacked(page))

		return MM_SHMEMPAGES;

	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(mm, MM_ANONPAGES);

		get_mm_counter(mm, MM_ANONPAGES) +

		get_mm_counter(mm, MM_SHMEMPAGES);

}



static inline unsigned long get_mm_hiwater_rss(struct mm_struct *mm)

include/linux/mm_types.h

+4 −3
Original line number Diff line number Diff line
@@ -369,9 +369,10 @@ 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 */

	MM_SHMEMPAGES,	/* Resident shared memory pages */

	NR_MM_COUNTERS

};

kernel/events/uprobes.c

+1 −1
Original line number Diff line number Diff line
@@ -180,7 +180,7 @@ 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);

	}