This is a note to let you know that I've just added the patch titled
zcache: fix deadlock condition
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also will be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 0ad6d118398c1f807646a36c91565fd275356b95 Mon Sep 17 00:00:00 2001
From: Dan Magenheimer <[email protected]>
Date: Wed, 25 Jan 2012 14:32:51 -0800
Subject: 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 <[email protected]>
Acked-by: Konrad Rzeszutek Wilk <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/staging/zcache/zcache-main.c | 7 +++----
1 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/zcache/zcache-main.c
b/drivers/staging/zcache/zcache-main.c
index 642840c..ae0ed82 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++;
--
1.7.9
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