On Mon, Nov 18, 2019 at 06:48:05PM -0800, Eric Biggers wrote: > On Mon, Nov 04, 2019 at 08:53:03AM -0800, Paul E. McKenney wrote: > > On Mon, Nov 04, 2019 at 05:14:50PM +0100, Marco Elver wrote: > > > On Mon, 4 Nov 2019 at 17:11, Paul E. McKenney <paulmck@xxxxxxxxxx> wrote: > > > > > > > > On Mon, Nov 04, 2019 at 12:31:56PM +0100, Marco Elver wrote: > > > > > +RCU folks, since this is probably a data race in RCU. > > > > > > > > > > On Mon, 4 Nov 2019 at 12:29, syzbot > > > > > <syzbot+08f3e9d26e5541e1ecf2@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > > > > Hello, > > > > > > > > > > > > syzbot found the following crash on: > > > > > > > > > > > > HEAD commit: 05f22368 x86, kcsan: Enable KCSAN for x86 > > > > > > git tree: https://github.com/google/ktsan.git kcsan > > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=17ade7ef600000 > > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=87d111955f40591f > > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=08f3e9d26e5541e1ecf2 > > > > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > > > > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > > > > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > > > > Reported-by: syzbot+08f3e9d26e5541e1ecf2@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > > > > > > > ================================================================== > > > > > > BUG: KCSAN: data-race in process_srcu / synchronize_srcu > > > > > > > > > > > > write to 0xffffffff8604e8a0 of 8 bytes by task 17 on cpu 1: > > > > > > srcu_gp_end kernel/rcu/srcutree.c:533 [inline] > > > > > > srcu_advance_state kernel/rcu/srcutree.c:1146 [inline] > > > > > > process_srcu+0x207/0x780 kernel/rcu/srcutree.c:1237 > > > > > > process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 > > > > > > worker_thread+0xa0/0x800 kernel/workqueue.c:2415 > > > > > > kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 > > > > > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 > > > > > > > > > > > > read to 0xffffffff8604e8a0 of 8 bytes by task 12515 on cpu 0: > > > > > > srcu_might_be_idle kernel/rcu/srcutree.c:784 [inline] > > > > > > synchronize_srcu+0x107/0x214 kernel/rcu/srcutree.c:996 > > > > > > fsnotify_connector_destroy_workfn+0x63/0xb0 fs/notify/mark.c:164 > > > > > > process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 > > > > > > worker_thread+0xa0/0x800 kernel/workqueue.c:2415 > > > > > > kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 > > > > > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 > > > > > > > > > > > > Reported by Kernel Concurrency Sanitizer on: > > > > > > CPU: 0 PID: 12515 Comm: kworker/u4:8 Not tainted 5.4.0-rc3+ #0 > > > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > > > > > Google 01/01/2011 > > > > > > Workqueue: events_unbound fsnotify_connector_destroy_workfn > > > > > > ================================================================== > > > > > > Kernel panic - not syncing: panic_on_warn set ... > > > > > > CPU: 0 PID: 12515 Comm: kworker/u4:8 Not tainted 5.4.0-rc3+ #0 > > > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > > > > > Google 01/01/2011 > > > > > > Workqueue: events_unbound fsnotify_connector_destroy_workfn > > > > > > Call Trace: > > > > > > __dump_stack lib/dump_stack.c:77 [inline] > > > > > > dump_stack+0xf5/0x159 lib/dump_stack.c:113 > > > > > > panic+0x210/0x640 kernel/panic.c:221 > > > > > > kcsan_report.cold+0xc/0x10 kernel/kcsan/report.c:302 > > > > > > __kcsan_setup_watchpoint+0x32e/0x4a0 kernel/kcsan/core.c:411 > > > > > > __tsan_read8 kernel/kcsan/kcsan.c:36 [inline] > > > > > > __tsan_read8+0x2c/0x30 kernel/kcsan/kcsan.c:36 > > > > > > srcu_might_be_idle kernel/rcu/srcutree.c:784 [inline] > > > > > > synchronize_srcu+0x107/0x214 kernel/rcu/srcutree.c:996 > > > > > > fsnotify_connector_destroy_workfn+0x63/0xb0 fs/notify/mark.c:164 > > > > > > process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 > > > > > > worker_thread+0xa0/0x800 kernel/workqueue.c:2415 > > > > > > kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 > > > > > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 > > > > > > Kernel Offset: disabled > > > > > > Rebooting in 86400 seconds.. > > > > > > > > > > > > > > > > > > --- > > > > > > This bug is generated by a bot. It may contain errors. > > > > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > > > > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > > > > > > > > > > > syzbot will keep track of this bug report. See: > > > > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > > > > > Good catch! Does the patch below help? > > > > > > Looks good to me, thanks for the quick fix. > > > > > > Acked-by: Marco Elver <elver@xxxxxxxxxx> > > > > Applied, thank you! > > > > Thanx, Paul > > This patch is not in linux-next. What happened to it? It is in -rcu, but arrived too late to make my pull request for v5.5. It will hit -next shortly after v5.5-rc1. Thanx, Paul
