e64e469b9a
Heiner reported a lockdep splat [1] This is caused by attempting GFP_KERNEL allocation while RCU lock is held and BH blocked. We believe that addrconf_verify_rtnl() could run for a long period, so instead of using GFP_ATOMIC here as Ido suggested, we should break the critical section and restart it after the allocation. [1] [86220.125562] ============================= [86220.125586] WARNING: suspicious RCU usage [86220.125612] 4.15.0-rc7-next-20180110+ #7 Not tainted [86220.125641] ----------------------------- [86220.125666] kernel/sched/core.c:6026 Illegal context switch in RCU-bh read-side critical section! [86220.125711] other info that might help us debug this: [86220.125755] rcu_scheduler_active = 2, debug_locks = 1 [86220.125792] 4 locks held by kworker/0:2/1003: [86220.125817] #0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000da8e9b73>] process_one_work+0x1de/0x680 [86220.125895] #1: ((addr_chk_work).work){+.+.}, at: [<00000000da8e9b73>] process_one_work+0x1de/0x680 [86220.125959] #2: (rtnl_mutex){+.+.}, at: [<00000000b06d9510>] rtnl_lock+0x12/0x20 [86220.126017] #3: (rcu_read_lock_bh){....}, at: [<00000000aef52299>] addrconf_verify_rtnl+0x1e/0x510 [ipv6] [86220.126111] stack backtrace: [86220.126142] CPU: 0 PID: 1003 Comm: kworker/0:2 Not tainted 4.15.0-rc7-next-20180110+ #7 [86220.126185] Hardware name: ZOTAC ZBOX-CI321NANO/ZBOX-CI321NANO, BIOS B246P105 06/01/2015 [86220.126250] Workqueue: ipv6_addrconf addrconf_verify_work [ipv6] [86220.126288] Call Trace: [86220.126312] dump_stack+0x70/0x9e [86220.126337] lockdep_rcu_suspicious+0xce/0xf0 [86220.126365] ___might_sleep+0x1d3/0x240 [86220.126390] __might_sleep+0x45/0x80 [86220.126416] kmem_cache_alloc_trace+0x53/0x250 [86220.126458] ? ipv6_add_addr+0xfe/0x6e0 [ipv6] [86220.126498] ipv6_add_addr+0xfe/0x6e0 [ipv6] [86220.126538] ipv6_create_tempaddr+0x24d/0x430 [ipv6] [86220.126580] ? ipv6_create_tempaddr+0x24d/0x430 [ipv6] [86220.126623] addrconf_verify_rtnl+0x339/0x510 [ipv6] [86220.126664] ? addrconf_verify_rtnl+0x339/0x510 [ipv6] [86220.126708] addrconf_verify_work+0xe/0x20 [ipv6] [86220.126738] process_one_work+0x258/0x680 [86220.126765] worker_thread+0x35/0x3f0 [86220.126790] kthread+0x124/0x140 [86220.126813] ? process_one_work+0x680/0x680 [86220.126839] ? kthread_create_worker_on_cpu+0x40/0x40 [86220.126869] ? umh_complete+0x40/0x40 [86220.126893] ? call_usermodehelper_exec_async+0x12a/0x160 [86220.126926] ret_from_fork+0x4b/0x60 [86220.126999] BUG: sleeping function called from invalid context at mm/slab.h:420 [86220.127041] in_atomic(): 1, irqs_disabled(): 0, pid: 1003, name: kworker/0:2 [86220.127082] 4 locks held by kworker/0:2/1003: [86220.127107] #0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000da8e9b73>] process_one_work+0x1de/0x680 [86220.127179] #1: ((addr_chk_work).work){+.+.}, at: [<00000000da8e9b73>] process_one_work+0x1de/0x680 [86220.127242] #2: (rtnl_mutex){+.+.}, at: [<00000000b06d9510>] rtnl_lock+0x12/0x20 [86220.127300] #3: (rcu_read_lock_bh){....}, at: [<00000000aef52299>] addrconf_verify_rtnl+0x1e/0x510 [ipv6] [86220.127414] CPU: 0 PID: 1003 Comm: kworker/0:2 Not tainted 4.15.0-rc7-next-20180110+ #7 [86220.127463] Hardware name: ZOTAC ZBOX-CI321NANO/ZBOX-CI321NANO, BIOS B246P105 06/01/2015 [86220.127528] Workqueue: ipv6_addrconf addrconf_verify_work [ipv6] [86220.127568] Call Trace: [86220.127591] dump_stack+0x70/0x9e [86220.127616] ___might_sleep+0x14d/0x240 [86220.127644] __might_sleep+0x45/0x80 [86220.127672] kmem_cache_alloc_trace+0x53/0x250 [86220.127717] ? ipv6_add_addr+0xfe/0x6e0 [ipv6] [86220.127762] ipv6_add_addr+0xfe/0x6e0 [ipv6] [86220.127807] ipv6_create_tempaddr+0x24d/0x430 [ipv6] [86220.127854] ? ipv6_create_tempaddr+0x24d/0x430 [ipv6] [86220.127903] addrconf_verify_rtnl+0x339/0x510 [ipv6] [86220.127950] ? addrconf_verify_rtnl+0x339/0x510 [ipv6] [86220.127998] addrconf_verify_work+0xe/0x20 [ipv6] [86220.128032] process_one_work+0x258/0x680 [86220.128063] worker_thread+0x35/0x3f0 [86220.128091] kthread+0x124/0x140 [86220.128117] ? process_one_work+0x680/0x680 [86220.128146] ? kthread_create_worker_on_cpu+0x40/0x40 [86220.128180] ? umh_complete+0x40/0x40 [86220.128207] ? call_usermodehelper_exec_async+0x12a/0x160 [86220.128243] ret_from_fork+0x4b/0x60 Fixes: f3d9832e56c4 ("ipv6: addrconf: cleanup locking in ipv6_add_addr") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Heiner Kallweit <hkallweit1@gmail.com> Reviewed-by: Ido Schimmel <idosch@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.