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Wed, 8 Jan 2020 12:23:30 +0100 (CET) To: linux-wireless@vger.kernel.org From: Markus Theil Subject: Possible deadlock in cfg80211 Autocrypt: addr=markus.theil@tu-ilmenau.de; keydata= mQINBFcopAYBEADBcwd5L8+T0zgqq4kYY4nQt6CYh5sOalHdI3zNE6fWbRbzQwViIlC9Q0q/ ys+nMmQajMWHalsgcdeVSQ2GJ/06qhtogCpmL3d2/GdlvVROh33zeqwqevscKvPH5i7oiBhh dMs8/5g89q4aTYtyaausy8qQbv3Q8BCVkwFW2pEcqfxNKgWi/8nM2A3powNA9gzCR2rmoGyd nvQNkk0MCwT8JSGnUkiEYEkWF4aIr3XToavpn+OMIIIizcDzRwU5NBmC3Q07PQTn8Srr+rJQ DF65vgaoI8G7wlNLQYavL1uFX1LVMP1jVr6GMOczeURqiF/QSuHCdyT3R8P3Qknc74tGT2Ow EbxllMnk1gvSfGQq47EYIvuXFyMUWOjjtgP+NxryXVAvQBmuqWWjRjfqMSx9URhvB/ZMQLbZ LUPNW0Whl/vOQdxVbEMQOSKhKYoWKeCDe7567sEi02bMScvr6ybKBvRMs71hT1T+HFcBE/IJ g3ZX+6qRzs+XKLTFGipRbRiLYKKNR+UM/sNc/w+3BTowB9g/cQukrITvb792T4/IPBJzpEry 9eZFhFTlIqggy/fGrpZkEpEsOyOWYlRyseETvNdrdeVG7dRGPj68jKUWTVcAaAAiu8WhgnvG 4tvpaORUhjdg4DfkbE9b9lvYkeesFsE0bUAd5z2DeVbtR0QBUwARAQABtClNYXJrdXMgVGhl aWwgPG1hcmt1cy50aGVpbEB0dS1pbG1lbmF1LmRlPokCPQQTAQoAJwUCVyikBgIbAwUJB4Yf gAULCQgHAwUVCgkICwUWAgMBAAIeAQIXgAAKCRBt3CLaT/oEE5bzD/94Ezfl7mm57PXniW3m yIcjofJXw7YCJOprUon36W2Na2xrH3j8QH/sqkfTyCoj1LWxxDGQs+CQGkZ47cX+H1KqKKSS iGoNRV/cvoozWe7cn9bAvR3JkqLxjIi0vp68rs/f6ZI49N7zuZAsSBrXN2/2xIgH+mRoAPyw mgzaIXZL87vajXol4TlbMaC7blRs6Q4kzOP7ZjvfM/yxwUsifQltNY4wAEWKXLk67ij9akGO FG+y3sHF1HYH3w0sB+mIIN3x4BjYqXSH3XDx4xvCQXWkHmFl1RoQbJDvMjxP5/HXLR3omPjF ZpV657Grh/PgonwZ/U6sigaA11pjcPfkYNYkcGyb0OMqSKb3Ke52/bhxv4pPWrKRS7btMhj7 4zuMDk9V+De3YFXvKGllXBMAA6J8TlY71rlcOWKyBQNLLkUZ7/uAA949GTNzM0fPTRqry5qn WCR/ekzm3VyFgjWSun39L1W13bJW8aUu8k5x2KWq4YrdB0TOYZpKSAconOHVxhkEMxLwRUfZ B9kEPqlfQY5YYE6ZoZQF38Kvx3VFuAnhf+82PjMMrkQ3g07D3xJlq7xWdq1jrwG1QxmVFS64 g+oWM9IIFisvVspNrJAEgSGmYgTw+VT3PDP3Gj8sqD32mWb18bVE9I5FyagOewKdLpqcljIi Bz8WAuz+RbwX4i/mMrkCDQRXKKQGARAAzTGnHyUtTBcGHMKArcGiVnCB6knTFgU7I1gsoBrc J1bo0JRJj1lduYkdm12kC49c4dZtv1CciQIN9UEpalZsB2TXaC/xaDJ2IsZuHLOOaqSSwVg/ Bs41vMeFYmmwRRN1y6MQRCBobCC6KNuCpgtEmS/v4hurISt+MoPIppjK6E7tJQ0lgtfRHq/M HW+Wabw5Nq3OFSaLYC3nRJkoB1Vej8XGO8X6URWnZmL3xcnkIkoH13y2WTO0lJz9tF47t5U2 +xWrFMR+a6ow/QPL4Wi53IqhXDqa6OUzDAUuplZOm71VhwsEkk6u0YjzNRbgAYMBh7iye2j/ 4Lf2+YUB8+uKimpsEwW0nR85sKCQm102Zb9+1bYXPuIIP9HbVNy77X4aM9V0W48zBTqWZzh8 2i0oq8z1xN3qeuZbAXnzelKZvE1wM9cLQ3YHA629J2OGe3dkv2+untuyj6KMCEU3+vp6j7TX hKf+jy3PIrQcQmzMTs7xnkEm5LvbAtaZLrg4OGYjSpvH4bKsLA3sNGt5Xqsuqh5dsO7ccX1G nfY7Ug8UyNT5/0gZVkOileTQl0KtgwO9VBXAdrmMPHFldRn3dGNiGlCbxnsaNQDfQwTFmDu0 1TjzwC4byWLQT+C7yCTk8h9q0NwmCJ5yG7Fe7VUUpA+ZVLyMSt+tSpH8v3n+3I2AKoMAEQEA AYkCJQQYAQoADwUCVyikBgIbDAUJB4YfgAAKCRBt3CLaT/oEE7lZEACgrOxRaCQ7D5Rc4BOA N4VDIQqVch8X3pBE/k/v3UopkgmYnP4RlhegWr4wp2E6Vuyt8nwnZs3WhxQENfMjd5rV3WhG k5ib+pmLvtAht5j8jfP5+UKUTvX1a6oMi98PT8PuQ70oKM7T/KN+RpXIHoz/2Dgde1RQpwKC XWtkU9tBF87fE8FfwuqS6myOfd8zc6fOVV/fxmTXVC8qA7tB+0tOSDHB80GRYwnlumChOtOB Np8ABFWryE2e6mZZnp9Tpd1A74B45z6l445f5BixGLExAOoTJNA2k0JWx79/2Yi+pwTnQMzW QBLa48MnL3DUlVlahz1FZfGbA2U5NARS8iRdUhCaHL0Lph8HxWJwYA5w2afyCCwRD7xFo44V jsCNbqtZ6TrFARJdrbeWQl3RZ4Y+uuvN9mgvttVenAbx5d68IariYtXashucQeIMoqIloHTN sJDaupNm6+A9T3Re5yXmZsrWSxEEEGv1Bh+5DH6vauP0Ng0ebZ4c6jXfgLpPnAUWlV0rnmrJ q9141nbyLRYAhUXxiqajb+Zocp2Am4BF19rBUa1C78ooye9XShhuQvDTB6tZuiYWc24tiyqb IjR1hmG/zg8APhURAv/zUubaf4IA7v5YHVQqAbpUfb6ePlPVJBtVw2CwXFrGwnqDFh82La8D sGZPq8zmOtvOyZtafA== Message-ID: <64dc212d-fde7-ab84-369c-c7cb5bf579d7@tu-ilmenau.de> Date: Wed, 8 Jan 2020 12:23:29 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Hi, while testing hostapd with hwsim, the following deadlock was reported: [  500.865102] ============================================ [  500.865106] WARNING: possible recursive locking detected [  500.865112] 5.4.8-arch1-1 #1 Not tainted [  500.865117] -------------------------------------------- [  500.865122] kworker/3:0/36 is trying to acquire lock: [  500.865127] ffff8881acdf0d08 (&wdev->mtx){+.+.}, at: cfg80211_stop_ap+0x37/0x60 [cfg80211] [  500.865249]                but task is already holding lock: [  500.865253] ffff8881acdf0d08 (&wdev->mtx){+.+.}, at: cfg80211_autodisconnect_wk+0x3d/0x190 [cfg80211] [  500.865354]                other info that might help us debug this: [  500.865358]  Possible unsafe locking scenario: [  500.865363]        CPU0 [  500.865366]        ---- [  500.865369]   lock(&wdev->mtx); [  500.865373]   lock(&wdev->mtx); [  500.865378]                 *** DEADLOCK *** [  500.865382]  May be due to missing lock nesting notation [  500.865388] 3 locks held by kworker/3:0/36: [  500.865391]  #0: ffff8881d4c22148 ((wq_completion)events){+.+.}, at: process_one_work+0x4ee/0xac0 [  500.865407]  #1: ffff8881d4327dc8 ((work_completion)(&wdev->disconnect_wk)){+.+.}, at: process_one_work+0x4ee/0xac0 [  500.865418]  #2: ffff8881acdf0d08 (&wdev->mtx){+.+.}, at: cfg80211_autodisconnect_wk+0x3d/0x190 [cfg80211] [  500.865517]                stack backtrace: [  500.865524] CPU: 3 PID: 36 Comm: kworker/3:0 Not tainted 5.4.8-arch1-1 #1 [  500.865530] Hardware name: LENOVO 2349QM6/2349QM6, BIOS G1ETC2WW (2.82 ) 08/07/2019 [  500.865628] Workqueue: events cfg80211_autodisconnect_wk [cfg80211] [  500.865634] Call Trace: [  500.865645]  dump_stack+0xb8/0x110 [  500.865654]  __lock_acquire.cold+0xe2/0x212 [  500.865672]  ? lockdep_hardirqs_on+0x260/0x260 [  500.865681]  ? find_held_lock+0x8c/0xa0 [  500.865693]  lock_acquire+0xe5/0x220 [  500.865772]  ? cfg80211_stop_ap+0x37/0x60 [cfg80211] [  500.865783]  __mutex_lock+0x137/0xd00 [  500.865864]  ? cfg80211_stop_ap+0x37/0x60 [cfg80211] [  500.865873]  ? preempt_count_sub+0x14/0xc0 [  500.865880]  ? __mutex_lock+0x71f/0xd00 [  500.865888]  ? find_first_zero_bit+0x28/0x50 [  500.865977]  ? cfg80211_stop_ap+0x37/0x60 [cfg80211] [  500.865986]  ? mutex_lock_io_nested+0xc20/0xc20 [  500.866090]  ? cfg80211_autodisconnect_wk+0x3d/0x190 [cfg80211] [  500.866098]  ? mutex_lock_io_nested+0xc20/0xc20 [  500.866109]  ? lockdep_hardirqs_on+0x260/0x260 [  500.866116]  ? match_held_lock+0x2e/0x240 [  500.866127]  ? preempt_count_sub+0x14/0xc0 [  500.866224]  ? cfg80211_stop_ap+0x37/0x60 [cfg80211] [  500.866322]  cfg80211_stop_ap+0x37/0x60 [cfg80211] [  500.866433]  cfg80211_autodisconnect_wk+0xd5/0x190 [cfg80211] [  500.866445]  process_one_work+0x5c0/0xac0 [  500.866460]  ? pwq_dec_nr_in_flight+0x110/0x110 [  500.866480]  worker_thread+0x7a/0x690 [  500.866497]  kthread+0x1ab/0x200 [  500.866505]  ? process_one_work+0xac0/0xac0 [  500.866511]  ? kthread_create_on_node+0xd0/0xd0 [  500.866521]  ret_from_fork+0x3a/0x50 Markus