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| author | Brian King <brking@linux.vnet.ibm.com> | 2010-09-10 09:03:21 +0200 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2010-09-10 09:03:21 +0200 |
| commit | be14eb619108fa8b7120eb2c42d66d5f623ae10e (patch) | |
| tree | cfc8a496c62a429a97c4bc2c5e638c39374f560b /block | |
| parent | edce6820a9fdda85521211cb334a183e34cc455e (diff) | |
| download | lwn-be14eb619108fa8b7120eb2c42d66d5f623ae10e.tar.gz lwn-be14eb619108fa8b7120eb2c42d66d5f623ae10e.zip | |
block: Range check cpu in blk_cpu_to_group
While testing CPU DLPAR, the following problem was discovered.
We were DLPAR removing the first CPU, which in this case was
logical CPUs 0-3. CPUs 0-2 were already marked offline and
we were in the process of offlining CPU 3. After marking
the CPU inactive and offline in cpu_disable, but before the
cpu was completely idle (cpu_die), we ended up in __make_request
on CPU 3. There we looked at the topology map to see which CPU
to complete the I/O on and found no CPUs in the cpu_sibling_map.
This resulted in the block layer setting the completion cpu
to be NR_CPUS, which then caused an oops when we tried to
complete the I/O.
Fix this by sanity checking the value we return from blk_cpu_to_group
to be a valid cpu value.
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/block/blk.h b/block/blk.h index 6e7dc87141e4..d6b911ac002c 100644 --- a/block/blk.h +++ b/block/blk.h @@ -142,14 +142,18 @@ static inline int queue_congestion_off_threshold(struct request_queue *q) static inline int blk_cpu_to_group(int cpu) { + int group = NR_CPUS; #ifdef CONFIG_SCHED_MC const struct cpumask *mask = cpu_coregroup_mask(cpu); - return cpumask_first(mask); + group = cpumask_first(mask); #elif defined(CONFIG_SCHED_SMT) - return cpumask_first(topology_thread_cpumask(cpu)); + group = cpumask_first(topology_thread_cpumask(cpu)); #else return cpu; #endif + if (likely(group < NR_CPUS)) + return group; + return cpu; } /* |