From 9256a4789be3dae37d00924c03546ba7958ea5a3 Mon Sep 17 00:00:00 2001 From: Dan Magenheimer Date: Wed, 25 Jan 2012 14:32:51 -0800 Subject: [PATCH] zcache: fix deadlock condition I discovered this deadlock condition awhile ago working on RAMster but it affects zcache as well. The list spinlock must be locked prior to the page spinlock and released after. As a result, the page copy must also be done while the locks are held. Applies to 3.2. Konrad, please push (via GregKH?)... this is definitely a bug fix so need not be pushed during a -rc0 window. Signed-off-by: Dan Magenheimer Acked-by: Konrad Rzeszutek Wilk Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/staging/zcache/zcache-main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c index 642840c612ac..ae0ed82dd3cb 100644 --- a/drivers/staging/zcache/zcache-main.c +++ b/drivers/staging/zcache/zcache-main.c @@ -358,8 +358,8 @@ static struct zbud_hdr *zbud_create(uint16_t client_id, uint16_t pool_id, if (unlikely(zbpg == NULL)) goto out; /* ok, have a page, now compress the data before taking locks */ - spin_lock(&zbpg->lock); spin_lock(&zbud_budlists_spinlock); + spin_lock(&zbpg->lock); list_add_tail(&zbpg->bud_list, &zbud_unbuddied[nchunks].list); zbud_unbuddied[nchunks].count++; zh = &zbpg->buddy[0]; @@ -389,12 +389,11 @@ init_zh: zh->oid = *oid; zh->pool_id = pool_id; zh->client_id = client_id; - /* can wait to copy the data until the list locks are dropped */ - spin_unlock(&zbud_budlists_spinlock); - to = zbud_data(zh, size); memcpy(to, cdata, size); spin_unlock(&zbpg->lock); + spin_unlock(&zbud_budlists_spinlock); + zbud_cumul_chunk_counts[nchunks]++; atomic_inc(&zcache_zbud_curr_zpages); zcache_zbud_cumul_zpages++; -- 2.20.1