+ z3fold-compact-objects-more-accurately.patch added to -mm tree

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The patch titled
     Subject: z3fold: compact objects more accurately
has been added to the -mm tree.  Its filename is
     z3fold-compact-objects-more-accurately.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/z3fold-compact-objects-more-accurately.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/z3fold-compact-objects-more-accurately.patch

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------------------------------------------------------
From: Vitaly Wool <vitalywool@xxxxxxxxx>
Subject: z3fold: compact objects more accurately

There are several small things to be considered regarding the new
inter-page compaction mechanism.  First, we better set the relevant size
in chunks to 0 in the old z3fold header for the object that has been moved
to another z3fold page.  Then, we shouldn't do inter-page compaction if an
object is mapped.  Lastly, free_handle should happen before
release_z3fold_page (but not in case the page is under reclaim, it will
the handle will be freed by reclaim then).

This patch addresses all three issues.

Link: http://lkml.kernel.org/r/20191127152216.6ad33745a21ba71c53606acb@xxxxxxxxx
Signed-off-by: Vitaly Wool <vitaly.vul@xxxxxxxx>
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Henry Burns <henrywolfeburns@xxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/z3fold.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/mm/z3fold.c~z3fold-compact-objects-more-accurately
+++ a/mm/z3fold.c
@@ -670,6 +670,7 @@ static struct z3fold_header *compact_sin
 	int first_idx = __idx(zhdr, FIRST);
 	int middle_idx = __idx(zhdr, MIDDLE);
 	int last_idx = __idx(zhdr, LAST);
+	unsigned short *moved_chunks = NULL;
 
 	/*
 	 * No need to protect slots here -- all the slots are "local" and
@@ -679,14 +680,17 @@ static struct z3fold_header *compact_sin
 		p += ZHDR_SIZE_ALIGNED;
 		sz = zhdr->first_chunks << CHUNK_SHIFT;
 		old_handle = (unsigned long)&zhdr->slots->slot[first_idx];
+		moved_chunks = &zhdr->first_chunks;
 	} else if (zhdr->middle_chunks && zhdr->slots->slot[middle_idx]) {
 		p += zhdr->start_middle << CHUNK_SHIFT;
 		sz = zhdr->middle_chunks << CHUNK_SHIFT;
 		old_handle = (unsigned long)&zhdr->slots->slot[middle_idx];
+		moved_chunks = &zhdr->middle_chunks;
 	} else if (zhdr->last_chunks && zhdr->slots->slot[last_idx]) {
 		p += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
 		sz = zhdr->last_chunks << CHUNK_SHIFT;
 		old_handle = (unsigned long)&zhdr->slots->slot[last_idx];
+		moved_chunks = &zhdr->last_chunks;
 	}
 
 	if (sz > 0) {
@@ -743,6 +747,8 @@ static struct z3fold_header *compact_sin
 		write_unlock(&zhdr->slots->lock);
 		add_to_unbuddied(pool, new_zhdr);
 		z3fold_page_unlock(new_zhdr);
+
+		*moved_chunks = 0;
 	}
 
 	return new_zhdr;
@@ -840,7 +846,7 @@ static void do_compact_page(struct z3fol
 	}
 
 	if (!zhdr->foreign_handles && buddy_single(zhdr) &&
-			compact_single_buddy(zhdr)) {
+	    zhdr->mapped_count == 0 && compact_single_buddy(zhdr)) {
 		if (kref_put(&zhdr->refcount, release_z3fold_page_locked))
 			atomic64_dec(&pool->pages_nr);
 		else
@@ -1254,6 +1260,8 @@ static void z3fold_free(struct z3fold_po
 		return;
 	}
 
+	if (!page_claimed)
+		free_handle(handle);
 	if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list)) {
 		atomic64_dec(&pool->pages_nr);
 		return;
@@ -1263,7 +1271,6 @@ static void z3fold_free(struct z3fold_po
 		z3fold_page_unlock(zhdr);
 		return;
 	}
-	free_handle(handle);
 	if (unlikely(PageIsolated(page)) ||
 	    test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
 		put_z3fold_header(zhdr);
_

Patches currently in -mm which might be from vitalywool@xxxxxxxxx are

z3fold-avoid-subtle-race-when-freeing-slots.patch
z3fold-compact-objects-more-accurately.patch
z3fold-protect-handle-reads.patch




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