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From: Roman Gushchin <guro@fb.com>
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To: Andrew Morton <akpm@linux-foundation.org>,
        Dennis Zhou
	<dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
        Christoph Lameter
	<cl@linux.com>
CC: Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@kernel.org>,
        Shakeel Butt <shakeelb@google.com>, <linux-mm@kvack.org>,
        <kernel-team@fb.com>, <linux-kernel@vger.kernel.org>,
        Roman Gushchin
	<guro@fb.com>
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Subject: [PATCH RFC 1/5] percpu: return number of released bytes from pcpu_free_area()
Date: Tue, 19 May 2020 13:18:02 -0700
Message-ID: <20200519201806.2308480-2-guro@fb.com>
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To implement accounting of percpu memory we need the information
about the size of freed object. Return it from pcpu_free_area().

Signed-off-by: Roman Gushchin <guro@fb.com>
---
 mm/percpu.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index 696367b18222..aa36b78d45a6 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1211,11 +1211,14 @@ static int pcpu_alloc_area(struct pcpu_chunk *chu=
nk, int alloc_bits,
  *
  * This function determines the size of an allocation to free using
  * the boundary bitmap and clears the allocation map.
+ *
+ * RETURNS:
+ * Number of freed bytes.
  */
-static void pcpu_free_area(struct pcpu_chunk *chunk, int off)
+static int pcpu_free_area(struct pcpu_chunk *chunk, int off)
 {
 	struct pcpu_block_md *chunk_md =3D &chunk->chunk_md;
-	int bit_off, bits, end, oslot;
+	int bit_off, bits, end, oslot, freed;
=20
 	lockdep_assert_held(&pcpu_lock);
 	pcpu_stats_area_dealloc(chunk);
@@ -1230,8 +1233,10 @@ static void pcpu_free_area(struct pcpu_chunk *chun=
k, int off)
 	bits =3D end - bit_off;
 	bitmap_clear(chunk->alloc_map, bit_off, bits);
=20
+	freed =3D bits * PCPU_MIN_ALLOC_SIZE;
+
 	/* update metadata */
-	chunk->free_bytes +=3D bits * PCPU_MIN_ALLOC_SIZE;
+	chunk->free_bytes +=3D freed;
=20
 	/* update first free bit */
 	chunk_md->first_free =3D min(chunk_md->first_free, bit_off);
@@ -1239,6 +1244,8 @@ static void pcpu_free_area(struct pcpu_chunk *chunk=
, int off)
 	pcpu_block_update_hint_free(chunk, bit_off, bits);
=20
 	pcpu_chunk_relocate(chunk, oslot);
+
+	return freed;
 }
=20
 static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
--=20
2.25.4