* [paulmckrcu:dev 42/49] kernel/smp.c:251 csd_lock_wait_toolong() warn: variable dereferenced before check 'nmessages' (see line 251)
@ 2024-07-04 12:44 kernel test robot
0 siblings, 0 replies; 3+ messages in thread
From: kernel test robot @ 2024-07-04 12:44 UTC (permalink / raw)
To: oe-kbuild; +Cc: lkp, Dan Carpenter
BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: "Paul E. McKenney" <paulmck@kernel.org>
tree: https://github.com/paulmckrcu/linux dev
head: 98800981bc4f02066887d7f0bd41cb7070fbcc94
commit: feca218cf89f7ff46d90ac4e0bd126ecfc423fd2 [42/49] locking/csd-lock: Use backoff for repeated reports of same incident
:::::: branch date: 13 hours ago
:::::: commit date: 2 days ago
config: x86_64-randconfig-161-20240704 (https://download.01.org/0day-ci/archive/20240704/202407042011.FX2T2Rea-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202407042011.FX2T2Rea-lkp@intel.com/
smatch warnings:
kernel/smp.c:251 csd_lock_wait_toolong() warn: variable dereferenced before check 'nmessages' (see line 251)
vim +/nmessages +251 kernel/smp.c
24f4724edcdc91 Paul E. McKenney 2024-07-01 222
35feb60474bf4f Paul E. McKenney 2020-06-30 223 /*
35feb60474bf4f Paul E. McKenney 2020-06-30 224 * Complain if too much time spent waiting. Note that only
35feb60474bf4f Paul E. McKenney 2020-06-30 225 * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
35feb60474bf4f Paul E. McKenney 2020-06-30 226 * so waiting on other types gets much less information.
35feb60474bf4f Paul E. McKenney 2020-06-30 227 */
feca218cf89f7f Paul E. McKenney 2024-07-02 228 static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id, unsigned long *nmessages)
35feb60474bf4f Paul E. McKenney 2020-06-30 229 {
35feb60474bf4f Paul E. McKenney 2020-06-30 230 int cpu = -1;
35feb60474bf4f Paul E. McKenney 2020-06-30 231 int cpux;
35feb60474bf4f Paul E. McKenney 2020-06-30 232 bool firsttime;
35feb60474bf4f Paul E. McKenney 2020-06-30 233 u64 ts2, ts_delta;
35feb60474bf4f Paul E. McKenney 2020-06-30 234 call_single_data_t *cpu_cur_csd;
545b8c8df41f9e Peter Zijlstra 2020-06-15 235 unsigned int flags = READ_ONCE(csd->node.u_flags);
3791a22374715b Paul E. McKenney 2022-02-28 236 unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC;
35feb60474bf4f Paul E. McKenney 2020-06-30 237
35feb60474bf4f Paul E. McKenney 2020-06-30 238 if (!(flags & CSD_FLAG_LOCK)) {
35feb60474bf4f Paul E. McKenney 2020-06-30 239 if (!unlikely(*bug_id))
35feb60474bf4f Paul E. McKenney 2020-06-30 240 return true;
35feb60474bf4f Paul E. McKenney 2020-06-30 241 cpu = csd_lock_wait_getcpu(csd);
35feb60474bf4f Paul E. McKenney 2020-06-30 242 pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
35feb60474bf4f Paul E. McKenney 2020-06-30 243 *bug_id, raw_smp_processor_id(), cpu);
24f4724edcdc91 Paul E. McKenney 2024-07-01 244 atomic_dec(&n_csd_lock_stuck);
35feb60474bf4f Paul E. McKenney 2020-06-30 245 return true;
35feb60474bf4f Paul E. McKenney 2020-06-30 246 }
35feb60474bf4f Paul E. McKenney 2020-06-30 247
35feb60474bf4f Paul E. McKenney 2020-06-30 248 ts2 = sched_clock();
94b3f0b5af2c7a Rik van Riel 2023-08-21 249 /* How long since we last checked for a stuck CSD lock.*/
35feb60474bf4f Paul E. McKenney 2020-06-30 250 ts_delta = ts2 - *ts1;
feca218cf89f7f Paul E. McKenney 2024-07-02 @251 if (likely(ts_delta <= csd_lock_timeout_ns * (*nmessages + 1) *
feca218cf89f7f Paul E. McKenney 2024-07-02 252 (!nmessages ? 1 : (ilog2(num_online_cpus()) / 2 + 1)) ||
feca218cf89f7f Paul E. McKenney 2024-07-02 253 csd_lock_timeout_ns == 0))
35feb60474bf4f Paul E. McKenney 2020-06-30 254 return false;
35feb60474bf4f Paul E. McKenney 2020-06-30 255
35feb60474bf4f Paul E. McKenney 2020-06-30 256 firsttime = !*bug_id;
35feb60474bf4f Paul E. McKenney 2020-06-30 257 if (firsttime)
35feb60474bf4f Paul E. McKenney 2020-06-30 258 *bug_id = atomic_inc_return(&csd_bug_count);
35feb60474bf4f Paul E. McKenney 2020-06-30 259 cpu = csd_lock_wait_getcpu(csd);
35feb60474bf4f Paul E. McKenney 2020-06-30 260 if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
35feb60474bf4f Paul E. McKenney 2020-06-30 261 cpux = 0;
35feb60474bf4f Paul E. McKenney 2020-06-30 262 else
35feb60474bf4f Paul E. McKenney 2020-06-30 263 cpux = cpu;
35feb60474bf4f Paul E. McKenney 2020-06-30 264 cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
94b3f0b5af2c7a Rik van Riel 2023-08-21 265 /* How long since this CSD lock was stuck. */
94b3f0b5af2c7a Rik van Riel 2023-08-21 266 ts_delta = ts2 - ts0;
a0897399e4ce39 Paul E. McKenney 2024-07-01 267 pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %lld ns for CPU#%02d %pS(%ps).\n",
a0897399e4ce39 Paul E. McKenney 2024-07-01 268 firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), (s64)ts_delta,
35feb60474bf4f Paul E. McKenney 2020-06-30 269 cpu, csd->func, csd->info);
feca218cf89f7f Paul E. McKenney 2024-07-02 270 (*nmessages)++;
24f4724edcdc91 Paul E. McKenney 2024-07-01 271 if (firsttime)
24f4724edcdc91 Paul E. McKenney 2024-07-01 272 atomic_dec(&n_csd_lock_stuck);
94b3f0b5af2c7a Rik van Riel 2023-08-21 273 /*
94b3f0b5af2c7a Rik van Riel 2023-08-21 274 * If the CSD lock is still stuck after 5 minutes, it is unlikely
94b3f0b5af2c7a Rik van Riel 2023-08-21 275 * to become unstuck. Use a signed comparison to avoid triggering
94b3f0b5af2c7a Rik van Riel 2023-08-21 276 * on underflows when the TSC is out of sync between sockets.
94b3f0b5af2c7a Rik van Riel 2023-08-21 277 */
94b3f0b5af2c7a Rik van Riel 2023-08-21 278 BUG_ON(panic_on_ipistall > 0 && (s64)ts_delta > ((s64)panic_on_ipistall * NSEC_PER_MSEC));
35feb60474bf4f Paul E. McKenney 2020-06-30 279 if (cpu_cur_csd && csd != cpu_cur_csd) {
35feb60474bf4f Paul E. McKenney 2020-06-30 280 pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
35feb60474bf4f Paul E. McKenney 2020-06-30 281 *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
35feb60474bf4f Paul E. McKenney 2020-06-30 282 READ_ONCE(per_cpu(cur_csd_info, cpux)));
35feb60474bf4f Paul E. McKenney 2020-06-30 283 } else {
35feb60474bf4f Paul E. McKenney 2020-06-30 284 pr_alert("\tcsd: CSD lock (#%d) %s.\n",
35feb60474bf4f Paul E. McKenney 2020-06-30 285 *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
35feb60474bf4f Paul E. McKenney 2020-06-30 286 }
35feb60474bf4f Paul E. McKenney 2020-06-30 287 if (cpu >= 0) {
0d3a00b370424f Imran Khan 2023-05-09 288 if (atomic_cmpxchg_acquire(&per_cpu(trigger_backtrace, cpu), 1, 0))
35feb60474bf4f Paul E. McKenney 2020-06-30 289 dump_cpu_task(cpu);
35feb60474bf4f Paul E. McKenney 2020-06-30 290 if (!cpu_cur_csd) {
35feb60474bf4f Paul E. McKenney 2020-06-30 291 pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
35feb60474bf4f Paul E. McKenney 2020-06-30 292 arch_send_call_function_single_ipi(cpu);
35feb60474bf4f Paul E. McKenney 2020-06-30 293 }
35feb60474bf4f Paul E. McKenney 2020-06-30 294 }
5bd00f6db012f7 Imran Khan 2023-05-09 295 if (firsttime)
35feb60474bf4f Paul E. McKenney 2020-06-30 296 dump_stack();
35feb60474bf4f Paul E. McKenney 2020-06-30 297 *ts1 = ts2;
35feb60474bf4f Paul E. McKenney 2020-06-30 298
35feb60474bf4f Paul E. McKenney 2020-06-30 299 return false;
35feb60474bf4f Paul E. McKenney 2020-06-30 300 }
35feb60474bf4f Paul E. McKenney 2020-06-30 301
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 3+ messages in thread* [paulmckrcu:dev 42/49] kernel/smp.c:251 csd_lock_wait_toolong() warn: variable dereferenced before check 'nmessages' (see line 251)
@ 2024-07-04 15:28 Dan Carpenter
2024-07-04 15:50 ` Paul E. McKenney
0 siblings, 1 reply; 3+ messages in thread
From: Dan Carpenter @ 2024-07-04 15:28 UTC (permalink / raw)
To: oe-kbuild, Paul E. McKenney; +Cc: lkp, oe-kbuild-all
tree: https://github.com/paulmckrcu/linux dev
head: 98800981bc4f02066887d7f0bd41cb7070fbcc94
commit: feca218cf89f7ff46d90ac4e0bd126ecfc423fd2 [42/49] locking/csd-lock: Use backoff for repeated reports of same incident
config: x86_64-randconfig-161-20240704 (https://download.01.org/0day-ci/archive/20240704/202407042011.FX2T2Rea-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202407042011.FX2T2Rea-lkp@intel.com/
smatch warnings:
kernel/smp.c:251 csd_lock_wait_toolong() warn: variable dereferenced before check 'nmessages' (see line 251)
vim +/nmessages +251 kernel/smp.c
feca218cf89f7f Paul E. McKenney 2024-07-02 228 static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id, unsigned long *nmessages)
35feb60474bf4f Paul E. McKenney 2020-06-30 229 {
35feb60474bf4f Paul E. McKenney 2020-06-30 230 int cpu = -1;
35feb60474bf4f Paul E. McKenney 2020-06-30 231 int cpux;
35feb60474bf4f Paul E. McKenney 2020-06-30 232 bool firsttime;
35feb60474bf4f Paul E. McKenney 2020-06-30 233 u64 ts2, ts_delta;
35feb60474bf4f Paul E. McKenney 2020-06-30 234 call_single_data_t *cpu_cur_csd;
545b8c8df41f9e Peter Zijlstra 2020-06-15 235 unsigned int flags = READ_ONCE(csd->node.u_flags);
3791a22374715b Paul E. McKenney 2022-02-28 236 unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC;
35feb60474bf4f Paul E. McKenney 2020-06-30 237
35feb60474bf4f Paul E. McKenney 2020-06-30 238 if (!(flags & CSD_FLAG_LOCK)) {
35feb60474bf4f Paul E. McKenney 2020-06-30 239 if (!unlikely(*bug_id))
35feb60474bf4f Paul E. McKenney 2020-06-30 240 return true;
35feb60474bf4f Paul E. McKenney 2020-06-30 241 cpu = csd_lock_wait_getcpu(csd);
35feb60474bf4f Paul E. McKenney 2020-06-30 242 pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
35feb60474bf4f Paul E. McKenney 2020-06-30 243 *bug_id, raw_smp_processor_id(), cpu);
24f4724edcdc91 Paul E. McKenney 2024-07-01 244 atomic_dec(&n_csd_lock_stuck);
35feb60474bf4f Paul E. McKenney 2020-06-30 245 return true;
35feb60474bf4f Paul E. McKenney 2020-06-30 246 }
35feb60474bf4f Paul E. McKenney 2020-06-30 247
35feb60474bf4f Paul E. McKenney 2020-06-30 248 ts2 = sched_clock();
94b3f0b5af2c7a Rik van Riel 2023-08-21 249 /* How long since we last checked for a stuck CSD lock.*/
35feb60474bf4f Paul E. McKenney 2020-06-30 250 ts_delta = ts2 - *ts1;
feca218cf89f7f Paul E. McKenney 2024-07-02 @251 if (likely(ts_delta <= csd_lock_timeout_ns * (*nmessages + 1) *
^^^^^^^^^^
Dereference
feca218cf89f7f Paul E. McKenney 2024-07-02 252 (!nmessages ? 1 : (ilog2(num_online_cpus()) / 2 + 1)) ||
^^^^^^^^^^
Checked too late
feca218cf89f7f Paul E. McKenney 2024-07-02 253 csd_lock_timeout_ns == 0))
35feb60474bf4f Paul E. McKenney 2020-06-30 254 return false;
35feb60474bf4f Paul E. McKenney 2020-06-30 255
35feb60474bf4f Paul E. McKenney 2020-06-30 256 firsttime = !*bug_id;
35feb60474bf4f Paul E. McKenney 2020-06-30 257 if (firsttime)
35feb60474bf4f Paul E. McKenney 2020-06-30 258 *bug_id = atomic_inc_return(&csd_bug_count);
35feb60474bf4f Paul E. McKenney 2020-06-30 259 cpu = csd_lock_wait_getcpu(csd);
35feb60474bf4f Paul E. McKenney 2020-06-30 260 if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
35feb60474bf4f Paul E. McKenney 2020-06-30 261 cpux = 0;
35feb60474bf4f Paul E. McKenney 2020-06-30 262 else
35feb60474bf4f Paul E. McKenney 2020-06-30 263 cpux = cpu;
35feb60474bf4f Paul E. McKenney 2020-06-30 264 cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
94b3f0b5af2c7a Rik van Riel 2023-08-21 265 /* How long since this CSD lock was stuck. */
94b3f0b5af2c7a Rik van Riel 2023-08-21 266 ts_delta = ts2 - ts0;
a0897399e4ce39 Paul E. McKenney 2024-07-01 267 pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %lld ns for CPU#%02d %pS(%ps).\n",
a0897399e4ce39 Paul E. McKenney 2024-07-01 268 firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), (s64)ts_delta,
35feb60474bf4f Paul E. McKenney 2020-06-30 269 cpu, csd->func, csd->info);
feca218cf89f7f Paul E. McKenney 2024-07-02 270 (*nmessages)++;
^^^^^^^^^^
24f4724edcdc91 Paul E. McKenney 2024-07-01 271 if (firsttime)
24f4724edcdc91 Paul E. McKenney 2024-07-01 272 atomic_dec(&n_csd_lock_stuck);
94b3f0b5af2c7a Rik van Riel 2023-08-21 273 /*
94b3f0b5af2c7a Rik van Riel 2023-08-21 274 * If the CSD lock is still stuck after 5 minutes, it is unlikely
94b3f0b5af2c7a Rik van Riel 2023-08-21 275 * to become unstuck. Use a signed comparison to avoid triggering
94b3f0b5af2c7a Rik van Riel 2023-08-21 276 * on underflows when the TSC is out of sync between sockets.
94b3f0b5af2c7a Rik van Riel 2023-08-21 277 */
94b3f0b5af2c7a Rik van Riel 2023-08-21 278 BUG_ON(panic_on_ipistall > 0 && (s64)ts_delta > ((s64)panic_on_ipistall * NSEC_PER_MSEC));
35feb60474bf4f Paul E. McKenney 2020-06-30 279 if (cpu_cur_csd && csd != cpu_cur_csd) {
35feb60474bf4f Paul E. McKenney 2020-06-30 280 pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
35feb60474bf4f Paul E. McKenney 2020-06-30 281 *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
35feb60474bf4f Paul E. McKenney 2020-06-30 282 READ_ONCE(per_cpu(cur_csd_info, cpux)));
35feb60474bf4f Paul E. McKenney 2020-06-30 283 } else {
35feb60474bf4f Paul E. McKenney 2020-06-30 284 pr_alert("\tcsd: CSD lock (#%d) %s.\n",
35feb60474bf4f Paul E. McKenney 2020-06-30 285 *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
35feb60474bf4f Paul E. McKenney 2020-06-30 286 }
35feb60474bf4f Paul E. McKenney 2020-06-30 287 if (cpu >= 0) {
0d3a00b370424f Imran Khan 2023-05-09 288 if (atomic_cmpxchg_acquire(&per_cpu(trigger_backtrace, cpu), 1, 0))
35feb60474bf4f Paul E. McKenney 2020-06-30 289 dump_cpu_task(cpu);
35feb60474bf4f Paul E. McKenney 2020-06-30 290 if (!cpu_cur_csd) {
35feb60474bf4f Paul E. McKenney 2020-06-30 291 pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
35feb60474bf4f Paul E. McKenney 2020-06-30 292 arch_send_call_function_single_ipi(cpu);
35feb60474bf4f Paul E. McKenney 2020-06-30 293 }
35feb60474bf4f Paul E. McKenney 2020-06-30 294 }
5bd00f6db012f7 Imran Khan 2023-05-09 295 if (firsttime)
35feb60474bf4f Paul E. McKenney 2020-06-30 296 dump_stack();
35feb60474bf4f Paul E. McKenney 2020-06-30 297 *ts1 = ts2;
35feb60474bf4f Paul E. McKenney 2020-06-30 298
35feb60474bf4f Paul E. McKenney 2020-06-30 299 return false;
35feb60474bf4f Paul E. McKenney 2020-06-30 300 }
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [paulmckrcu:dev 42/49] kernel/smp.c:251 csd_lock_wait_toolong() warn: variable dereferenced before check 'nmessages' (see line 251)
2024-07-04 15:28 Dan Carpenter
@ 2024-07-04 15:50 ` Paul E. McKenney
0 siblings, 0 replies; 3+ messages in thread
From: Paul E. McKenney @ 2024-07-04 15:50 UTC (permalink / raw)
To: Dan Carpenter; +Cc: oe-kbuild, lkp, oe-kbuild-all
On Thu, Jul 04, 2024 at 05:28:03PM +0200, Dan Carpenter wrote:
> tree: https://github.com/paulmckrcu/linux dev
> head: 98800981bc4f02066887d7f0bd41cb7070fbcc94
> commit: feca218cf89f7ff46d90ac4e0bd126ecfc423fd2 [42/49] locking/csd-lock: Use backoff for repeated reports of same incident
> config: x86_64-randconfig-161-20240704 (https://download.01.org/0day-ci/archive/20240704/202407042011.FX2T2Rea-lkp@intel.com/config)
> compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> | Closes: https://lore.kernel.org/r/202407042011.FX2T2Rea-lkp@intel.com/
>
> smatch warnings:
> kernel/smp.c:251 csd_lock_wait_toolong() warn: variable dereferenced before check 'nmessages' (see line 251)
>
> vim +/nmessages +251 kernel/smp.c
>
> feca218cf89f7f Paul E. McKenney 2024-07-02 228 static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id, unsigned long *nmessages)
> 35feb60474bf4f Paul E. McKenney 2020-06-30 229 {
> 35feb60474bf4f Paul E. McKenney 2020-06-30 230 int cpu = -1;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 231 int cpux;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 232 bool firsttime;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 233 u64 ts2, ts_delta;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 234 call_single_data_t *cpu_cur_csd;
> 545b8c8df41f9e Peter Zijlstra 2020-06-15 235 unsigned int flags = READ_ONCE(csd->node.u_flags);
> 3791a22374715b Paul E. McKenney 2022-02-28 236 unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 237
> 35feb60474bf4f Paul E. McKenney 2020-06-30 238 if (!(flags & CSD_FLAG_LOCK)) {
> 35feb60474bf4f Paul E. McKenney 2020-06-30 239 if (!unlikely(*bug_id))
> 35feb60474bf4f Paul E. McKenney 2020-06-30 240 return true;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 241 cpu = csd_lock_wait_getcpu(csd);
> 35feb60474bf4f Paul E. McKenney 2020-06-30 242 pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
> 35feb60474bf4f Paul E. McKenney 2020-06-30 243 *bug_id, raw_smp_processor_id(), cpu);
> 24f4724edcdc91 Paul E. McKenney 2024-07-01 244 atomic_dec(&n_csd_lock_stuck);
> 35feb60474bf4f Paul E. McKenney 2020-06-30 245 return true;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 246 }
> 35feb60474bf4f Paul E. McKenney 2020-06-30 247
> 35feb60474bf4f Paul E. McKenney 2020-06-30 248 ts2 = sched_clock();
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 249 /* How long since we last checked for a stuck CSD lock.*/
> 35feb60474bf4f Paul E. McKenney 2020-06-30 250 ts_delta = ts2 - *ts1;
> feca218cf89f7f Paul E. McKenney 2024-07-02 @251 if (likely(ts_delta <= csd_lock_timeout_ns * (*nmessages + 1) *
> ^^^^^^^^^^
> Dereference
>
> feca218cf89f7f Paul E. McKenney 2024-07-02 252 (!nmessages ? 1 : (ilog2(num_online_cpus()) / 2 + 1)) ||
> ^^^^^^^^^^
> Checked too late
Ah, that should be "!*nmessages", thank you! It is not possible for
nmessages to be NULL.
Thanx, Paul
> feca218cf89f7f Paul E. McKenney 2024-07-02 253 csd_lock_timeout_ns == 0))
> 35feb60474bf4f Paul E. McKenney 2020-06-30 254 return false;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 255
> 35feb60474bf4f Paul E. McKenney 2020-06-30 256 firsttime = !*bug_id;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 257 if (firsttime)
> 35feb60474bf4f Paul E. McKenney 2020-06-30 258 *bug_id = atomic_inc_return(&csd_bug_count);
> 35feb60474bf4f Paul E. McKenney 2020-06-30 259 cpu = csd_lock_wait_getcpu(csd);
> 35feb60474bf4f Paul E. McKenney 2020-06-30 260 if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
> 35feb60474bf4f Paul E. McKenney 2020-06-30 261 cpux = 0;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 262 else
> 35feb60474bf4f Paul E. McKenney 2020-06-30 263 cpux = cpu;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 264 cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 265 /* How long since this CSD lock was stuck. */
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 266 ts_delta = ts2 - ts0;
> a0897399e4ce39 Paul E. McKenney 2024-07-01 267 pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %lld ns for CPU#%02d %pS(%ps).\n",
> a0897399e4ce39 Paul E. McKenney 2024-07-01 268 firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), (s64)ts_delta,
> 35feb60474bf4f Paul E. McKenney 2020-06-30 269 cpu, csd->func, csd->info);
> feca218cf89f7f Paul E. McKenney 2024-07-02 270 (*nmessages)++;
> ^^^^^^^^^^
>
> 24f4724edcdc91 Paul E. McKenney 2024-07-01 271 if (firsttime)
> 24f4724edcdc91 Paul E. McKenney 2024-07-01 272 atomic_dec(&n_csd_lock_stuck);
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 273 /*
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 274 * If the CSD lock is still stuck after 5 minutes, it is unlikely
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 275 * to become unstuck. Use a signed comparison to avoid triggering
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 276 * on underflows when the TSC is out of sync between sockets.
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 277 */
> 94b3f0b5af2c7a Rik van Riel 2023-08-21 278 BUG_ON(panic_on_ipistall > 0 && (s64)ts_delta > ((s64)panic_on_ipistall * NSEC_PER_MSEC));
> 35feb60474bf4f Paul E. McKenney 2020-06-30 279 if (cpu_cur_csd && csd != cpu_cur_csd) {
> 35feb60474bf4f Paul E. McKenney 2020-06-30 280 pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
> 35feb60474bf4f Paul E. McKenney 2020-06-30 281 *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
> 35feb60474bf4f Paul E. McKenney 2020-06-30 282 READ_ONCE(per_cpu(cur_csd_info, cpux)));
> 35feb60474bf4f Paul E. McKenney 2020-06-30 283 } else {
> 35feb60474bf4f Paul E. McKenney 2020-06-30 284 pr_alert("\tcsd: CSD lock (#%d) %s.\n",
> 35feb60474bf4f Paul E. McKenney 2020-06-30 285 *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
> 35feb60474bf4f Paul E. McKenney 2020-06-30 286 }
> 35feb60474bf4f Paul E. McKenney 2020-06-30 287 if (cpu >= 0) {
> 0d3a00b370424f Imran Khan 2023-05-09 288 if (atomic_cmpxchg_acquire(&per_cpu(trigger_backtrace, cpu), 1, 0))
> 35feb60474bf4f Paul E. McKenney 2020-06-30 289 dump_cpu_task(cpu);
> 35feb60474bf4f Paul E. McKenney 2020-06-30 290 if (!cpu_cur_csd) {
> 35feb60474bf4f Paul E. McKenney 2020-06-30 291 pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
> 35feb60474bf4f Paul E. McKenney 2020-06-30 292 arch_send_call_function_single_ipi(cpu);
> 35feb60474bf4f Paul E. McKenney 2020-06-30 293 }
> 35feb60474bf4f Paul E. McKenney 2020-06-30 294 }
> 5bd00f6db012f7 Imran Khan 2023-05-09 295 if (firsttime)
> 35feb60474bf4f Paul E. McKenney 2020-06-30 296 dump_stack();
> 35feb60474bf4f Paul E. McKenney 2020-06-30 297 *ts1 = ts2;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 298
> 35feb60474bf4f Paul E. McKenney 2020-06-30 299 return false;
> 35feb60474bf4f Paul E. McKenney 2020-06-30 300 }
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2024-07-04 15:50 UTC | newest]
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2024-07-04 12:44 [paulmckrcu:dev 42/49] kernel/smp.c:251 csd_lock_wait_toolong() warn: variable dereferenced before check 'nmessages' (see line 251) kernel test robot
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2024-07-04 15:28 Dan Carpenter
2024-07-04 15:50 ` Paul E. McKenney
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