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authorVitaly Wool <vitalywool@gmail.com>2017-10-03 16:15:06 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-10-03 17:54:24 -0700
commit3552935742e0d5f0dafd823736f45bdaa7ba672c (patch)
tree43039ba93ba9302c5ff1dc10716510d104f1d8c0 /mm
parent6818600ff094ca255a7fe31838ad50c29656c3c5 (diff)
downloadlwn-3552935742e0d5f0dafd823736f45bdaa7ba672c.tar.gz
lwn-3552935742e0d5f0dafd823736f45bdaa7ba672c.zip
z3fold: fix stale list handling
Fix the situation when clear_bit() is called for page->private before the page pointer is actually assigned. While at it, remove work_busy() check because it is costly and does not give 100% guarantee anyway. Signed-off-by: Vitaly Wool <vitalywool@gmail.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: <Oleksiy.Avramchenko@sony.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/z3fold.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c
index b04fa3ba1bf2..b2ba2ba585f3 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -250,6 +250,7 @@ static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
WARN_ON(!list_empty(&zhdr->buddy));
set_bit(PAGE_STALE, &page->private);
+ clear_bit(NEEDS_COMPACTING, &page->private);
spin_lock(&pool->lock);
if (!list_empty(&page->lru))
list_del(&page->lru);
@@ -303,7 +304,6 @@ static void free_pages_work(struct work_struct *w)
list_del(&zhdr->buddy);
if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
continue;
- clear_bit(NEEDS_COMPACTING, &page->private);
spin_unlock(&pool->stale_lock);
cancel_work_sync(&zhdr->work);
free_z3fold_page(page);
@@ -624,10 +624,8 @@ lookup:
* stale pages list. cancel_work_sync() can sleep so we must make
* sure it won't be called in case we're in atomic context.
*/
- if (zhdr && (can_sleep || !work_pending(&zhdr->work) ||
- !unlikely(work_busy(&zhdr->work)))) {
+ if (zhdr && (can_sleep || !work_pending(&zhdr->work))) {
list_del(&zhdr->buddy);
- clear_bit(NEEDS_COMPACTING, &page->private);
spin_unlock(&pool->stale_lock);
if (can_sleep)
cancel_work_sync(&zhdr->work);