On Fri, 2016-10-07 at 22:03 +0200, Dmitry Vyukov wrote: > Hello, > > I am hitting lots of the following warnings while running syzkaller > fuzzer. Seems that path does not hold proper lock. > > WARNING: CPU: 1 PID: 12090 at fs/locks.c:610 locks_unlink_lock_ctx+0x2c7/0x370 > CPU: 1 PID: 12090 Comm: syz-executor Not tainted 4.8.0+ #28 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > ffff880038ba7728 ffffffff82d2b849 ffffffff00000016 fffffbfff10971e8 > ffffffff86e8c000 ffff880038ba7800 ffffffff86f42400 dffffc0000000000 > 0000000000000009 ffff880038ba77f0 ffffffff816a229a 0000000041b58ab3 > Call Trace: > [< inline >] __dump_stack lib/dump_stack.c:15 > [<ffffffff82d2b849>] dump_stack+0x12e/0x185 lib/dump_stack.c:51 > [<ffffffff816a229a>] panic+0x1e9/0x3f4 kernel/panic.c:153 > [<ffffffff81354fb9>] __warn+0x1c9/0x1e0 kernel/panic.c:509 > [<ffffffff813551a1>] warn_slowpath_null+0x31/0x40 kernel/panic.c:552 > [< inline >] locks_delete_global_locks fs/locks.c:610 > [<ffffffff8193b247>] locks_unlink_lock_ctx+0x2c7/0x370 fs/locks.c:739 > [<ffffffff8193b30f>] locks_delete_lock_ctx+0x1f/0x80 fs/locks.c:751 > [<ffffffff8193d329>] lease_modify+0x229/0x2e0 fs/locks.c:1370 > [< inline >] locks_remove_lease fs/locks.c:2528 > [<ffffffff81947408>] locks_remove_file+0x2d8/0x380 fs/locks.c:2551 > [<ffffffff8182eea6>] __fput+0x1a6/0x780 fs/file_table.c:200 > [<ffffffff8182f50a>] ____fput+0x1a/0x20 fs/file_table.c:244 > [<ffffffff813bae68>] task_work_run+0xf8/0x170 kernel/task_work.c:116 > [< inline >] exit_task_work include/linux/task_work.h:21 > [<ffffffff81364de4>] do_exit+0x864/0x2ad0 kernel/exit.c:828 > [<ffffffff813671cd>] do_group_exit+0x10d/0x330 kernel/exit.c:931 > [<ffffffff8138a57f>] get_signal+0x62f/0x15e0 kernel/signal.c:2307 > [<ffffffff811cf344>] do_signal+0x84/0x18f0 arch/x86/kernel/signal.c:807 > [<ffffffff8100629b>] exit_to_usermode_loop+0x13b/0x200 > arch/x86/entry/common.c:156 > [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:190 > [< inline >] syscall_return_slowpath arch/x86/entry/common.c:259 > [<ffffffff81008a4f>] do_syscall_64+0x49f/0x620 arch/x86/entry/common.c:285 > > On commit a6930aaee06755d1bdcfd943fbf614e4d92bb0c7 (Oct 5). (cc'ing Peter...) Well spotted. Yeah, I think you're right. The assertion is this: percpu_rwsem_assert_held(&file_rwsem); I'm guessing this is probably fallout from the lglock to rwsem conversion (commit aba376607383). >From a quick glance, I think we probably just need to down_read the file_rwsem in locks_remove_lease, prior to taking the flc_lock, and release it just afterward. I do want to go over the code a little more closely though to make sure other codepaths aren't missing that lock though. Thanks, -- Jeff Layton <jlayton@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
