linux-kernel - [PATCH] z3fold: avoid modifying HEADLESS page and minor cleanup

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Date:	Fri, 27 May 2016 18:06:07 +0200
From:	Vitaly Wool <vitalywool@...il.com>
To:	Linux-MM <linux-mm@...ck.org>, linux-kernel@...r.kernel.org
Cc:	Seth Jennings <sjenning@...hat.com>,
	Dan Streetman <ddstreet@...e.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] z3fold: avoid modifying HEADLESS page and minor cleanup

This patch fixes erroneous z3fold header access in a HEADLESS page
in reclaim function, and changes one remaining direct
handle-to-buddy conversion to use the appropriate helper.

Signed-off-by: Vitaly Wool <vitalywool@...il.com>
---
  mm/z3fold.c | 24 ++++++++++++++----------
  1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/mm/z3fold.c b/mm/z3fold.c
index 34917d5..8f9e89c 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -412,7 +412,7 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
  		/* HEADLESS page stored */
  		bud = HEADLESS;
  	} else {
-		bud = (handle - zhdr->first_num) & BUDDY_MASK;
+		bud = handle_to_buddy(handle);
  
  		switch (bud) {
  		case FIRST:
@@ -572,15 +572,19 @@ next:
  			pool->pages_nr--;
  			spin_unlock(&pool->lock);
  			return 0;
-		} else if (zhdr->first_chunks != 0 &&
-			   zhdr->last_chunks != 0 && zhdr->middle_chunks != 0) {
-			/* Full, add to buddied list */
-			list_add(&zhdr->buddy, &pool->buddied);
-		} else if (!test_bit(PAGE_HEADLESS, &page->private)) {
-			z3fold_compact_page(zhdr);
-			/* add to unbuddied list */
-			freechunks = num_free_chunks(zhdr);
-			list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+		}  else if (!test_bit(PAGE_HEADLESS, &page->private)) {
+			if (zhdr->first_chunks != 0 &&
+			    zhdr->last_chunks != 0 &&
+			    zhdr->middle_chunks != 0) {
+				/* Full, add to buddied list */
+				list_add(&zhdr->buddy, &pool->buddied);
+			} else {
+				z3fold_compact_page(zhdr);
+				/* add to unbuddied list */
+				freechunks = num_free_chunks(zhdr);
+				list_add(&zhdr->buddy,
+					 &pool->unbuddied[freechunks]);
+			}
  		}
  
  		/* add to beginning of LRU */
-- 
2.5.0