backport some LTS patches.
Benjamin Coddington (1): SUNRPC: Fix a race to wake a sync task
Eric Dumazet (2): net: linkwatch: use system_unbound_wq net: busy-poll: use ktime_get_ns() instead of local_clock()
include/net/busy_poll.h | 2 +- net/core/link_watch.c | 4 ++-- net/sunrpc/sched.c | 4 +++- 3 files changed, 6 insertions(+), 4 deletions(-)
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From: Eric Dumazet edumazet@google.com
stable inclusion from stable-v4.19.320 commit 3840189e4619af11f558e6faff80813f008246a6 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAYZ0U
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ Upstream commit 3e7917c0cdad835a5121520fc5686d954b7a61ab ]
linkwatch_event() grabs possibly very contended RTNL mutex.
system_wq is not suitable for such work.
Inspired by many noisy syzbot reports.
3 locks held by kworker/0:7/5266: #0: ffff888015480948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3206 [inline] #0: ffff888015480948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x90a/0x1830 kernel/workqueue.c:3312 #1: ffffc90003f6fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3207 [inline] , at: process_scheduled_works+0x945/0x1830 kernel/workqueue.c:3312 #2: ffffffff8fa6f208 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:276
Reported-by: syzbot syzkaller@googlegroups.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Kuniyuki Iwashima kuniyu@amazon.com Link: https://patch.msgid.link/20240805085821.1616528-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Liu Jian liujian56@huawei.com --- net/core/link_watch.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/core/link_watch.c b/net/core/link_watch.c index 7f51efb2b3ab..91991064a21a 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -135,9 +135,9 @@ static void linkwatch_schedule_work(int urgent) * override the existing timer. */ if (test_bit(LW_URGENT, &linkwatch_flags)) - mod_delayed_work(system_wq, &linkwatch_work, 0); + mod_delayed_work(system_unbound_wq, &linkwatch_work, 0); else - schedule_delayed_work(&linkwatch_work, delay); + queue_delayed_work(system_unbound_wq, &linkwatch_work, delay); }
From: Benjamin Coddington bcodding@redhat.com
stable inclusion from stable-v4.19.320 commit 06d281f0ad7504e9f250c6a9ef78d9e48cea5717 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAYZ0U
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ Upstream commit ed0172af5d6fc07d1b40ca82f5ca3979300369f7 ]
We've observed NFS clients with sync tasks sleeping in __rpc_execute waiting on RPC_TASK_QUEUED that have not responded to a wake-up from rpc_make_runnable(). I suspect this problem usually goes unnoticed, because on a busy client the task will eventually be re-awoken by another task completion or xprt event. However, if the state manager is draining the slot table, a sync task missing a wake-up can result in a hung client.
We've been able to prove that the waker in rpc_make_runnable() successfully calls wake_up_bit() (ie- there's no race to tk_runstate), but the wake_up_bit() call fails to wake the waiter. I suspect the waker is missing the load of the bit's wait_queue_head, so waitqueue_active() is false. There are some very helpful comments about this problem above wake_up_bit(), prepare_to_wait(), and waitqueue_active().
Fix this by inserting smp_mb__after_atomic() before the wake_up_bit(), which pairs with prepare_to_wait() calling set_current_state().
Signed-off-by: Benjamin Coddington bcodding@redhat.com Reviewed-by: Jeff Layton jlayton@kernel.org Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Liu Jian liujian56@huawei.com --- net/sunrpc/sched.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index a873c92a4898..aa0a245125ec 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -349,8 +349,10 @@ static void rpc_make_runnable(struct workqueue_struct *wq, if (RPC_IS_ASYNC(task)) { INIT_WORK(&task->u.tk_work, rpc_async_schedule); queue_work(wq, &task->u.tk_work); - } else + } else { + smp_mb__after_atomic(); wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED); + } }
/*
From: Eric Dumazet edumazet@google.com
stable inclusion from stable-v4.19.321 commit 1b1f0890fb51fc50bf990a800106a133f9036f32 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAYZ0U
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ Upstream commit 0870b0d8b393dde53106678a1e2cec9dfa52f9b7 ]
Typically, busy-polling durations are below 100 usec.
When/if the busy-poller thread migrates to another cpu, local_clock() can be off by +/-2msec or more for small values of HZ, depending on the platform.
Use ktimer_get_ns() to ensure deterministic behavior, which is the whole point of busy-polling.
Fixes: 060212928670 ("net: add low latency socket poll") Fixes: 9a3c71aa8024 ("net: convert low latency sockets to sched_clock()") Fixes: 37089834528b ("sched, net: Fixup busy_loop_us_clock()") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Mina Almasry almasrymina@google.com Cc: Willem de Bruijn willemb@google.com Reviewed-by: Joe Damato jdamato@fastly.com Link: https://patch.msgid.link/20240827114916.223377-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Liu Jian liujian56@huawei.com --- include/net/busy_poll.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h index 8f42f6f3af86..c45253ee08c9 100644 --- a/include/net/busy_poll.h +++ b/include/net/busy_poll.h @@ -73,7 +73,7 @@ static inline bool sk_can_busy_loop(struct sock *sk) static inline unsigned long busy_loop_current_time(void) { #ifdef CONFIG_NET_RX_BUSY_POLL - return (unsigned long)(local_clock() >> 10); + return (unsigned long)(ktime_get_ns() >> 10); #else return 0; #endif
-
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