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| author | Dan Magenheimer <dan.magenheimer@oracle.com> | 2012-01-25 14:32:51 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-02-13 11:17:04 -0800 |
| commit | 5c97f5b2d4924961479e862e8fe516ba217551b3 (patch) | |
| tree | 142849d515d6cdbf27898d457657f463359c6079 | |
| parent | c1efec8273372700693661f094324081d8f3ad3d (diff) | |
| download | kernel-common-5c97f5b2d4924961479e862e8fe516ba217551b3.tar.gz kernel-common-5c97f5b2d4924961479e862e8fe516ba217551b3.tar.bz2 kernel-common-5c97f5b2d4924961479e862e8fe516ba217551b3.zip | |
zcache: fix deadlock condition
commit 9256a4789be3dae37d00924c03546ba7958ea5a3 upstream.
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 <dan.magenheimer@oracle.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | 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 d3a8e6784b86..f5e469d588d3 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++; |