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Message-Id: <20170914155936.697bf347a00dacee7e7f3778@gmail.com> Date: Thu, 14 Sep 2017 15:59:36 +0200 From: Vitaly Wool <vitalywool@...il.com> To: Linux-MM <linux-mm@...ck.org>, linux-kernel@...r.kernel.org Cc: Dan Streetman <ddstreet@...e.org>, Andrew Morton <akpm@...ux-foundation.org>, Oleksiy.Avramchenko@...y.com Subject: [PATCH] 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-of-by: Vitaly Wool <vitalywool@...il.com> --- mm/z3fold.c | 6 ++---- 1 file 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 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp, * 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); -- 2.11.0
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