linux-kernel - deadlock between cpu_stopper & native_flush_tlb_others()->smp_call_function

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 3 Mar 2014 17:43:56 +0100
From:	Igor Mammedov <imammedo@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	prarit@...hat.com, riel@...hat.com, mgorman@...e.de,
	peterz@...radead.org, alex.shi@...el.com,
	Igor Mammedov <imammedo@...hat.com>, hpa@...or.com
Subject: deadlock between cpu_stopper &
 native_flush_tlb_others()->smp_call_function_many()

It looks like I hit a deadlock between smp_call_function_many() and
cpu_stopper threads.

Where smp_call_function_many() on CPU1 called from
native_flush_tlb_others() waits on call to be complete on
CPU2 while CPU2 waits on state synchronization in
multi_cpu_stop() which can't be completed until stop work
queued on CPU1 is completed, which can't be done since  CPU1
is busy looping in smp_call_function_many().


CPU1                                       CPU2
stop_machine()
 queue stop work on cpu 1&2

native_flush_tlb_others()
   smp_call_function_many()
      ...
---------------------------------------------------------
                                    cpu_stopper_thread()
                                       multi_cpu_stop()
                                          do {
                                             ...
                                             msdata->state == MULTI_STOP_PREPARE
                                             msdata->active_cpus == 0110
                                             msdata->thread_ack == 1
                                          } while (curstate != MULTI_STOP_EXIT)
                                    waiting until CPU1 ACKs state, i.e. thread_ack == 0
---------------------------------------------------------                                    
      ...
      if (wait) {
         for_cpu(0110) {
           csd_lock_wait(csd);
waiting until call on CPU2 is completed

Are there any suggestions on how to fix this nicely?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/