Hi Paul,
On Tue, Dec 14, 2021 at 3:28 PM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
>
> Hello!
>
> At first glance, a WRITE_ONCE() in rcu_segcblist_set_flags() would cure
> all these, but I thought I should double check. Thoughts?
I think rcu_segcblist_clear_flags also needs a WRITE_ONCE()
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
I tried to reproduce the KCSAN Bug Report on my virtual machine but I
can't, I don't know why (I have detected the KCSAN Bug in e1000 nic
driver using the same environment before)
1) My virtual machine:
kvm -cpu host -smp 16 -hda ./Images/debian10.qcow2 -m 4096 -net
user,hostfwd=tcp::5556-:22,hostfwd=tcp::5555-:19 -net nic,model=e1000
-vnc :30
2) The KCSAN kernel compile with clang-12:
CONFIG_HAVE_ARCH_KCSAN=y
CONFIG_HAVE_KCSAN_COMPILER=y
CONFIG_KCSAN=y
CONFIG_KCSAN_SELFTEST=y
# CONFIG_KCSAN_EARLY_ENABLE is not set
CONFIG_KCSAN_NUM_WATCHPOINTS=64
CONFIG_KCSAN_UDELAY_TASK=80
CONFIG_KCSAN_UDELAY_INTERRUPT=20
CONFIG_KCSAN_DELAY_RANDOMIZE=y
CONFIG_KCSAN_SKIP_WATCH=4000
CONFIG_KCSAN_SKIP_WATCH_RANDOMIZE=y
# CONFIG_KCSAN_INTERRUPT_WATCHER is not set
CONFIG_KCSAN_REPORT_ONCE_IN_MS=3000
# CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN is not set
# CONFIG_KCSAN_STRICT is not set
CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=y
# CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC is not set
CONFIG_KCSAN_IGNORE_ATOMICS=y
CONFIG_KCSAN_PERMISSIVE=y
3)kernel command line
root@debian:~# cat /proc/cmdline
earlyprintk=serial net.ifnames=0
sysctl.kernel.hung_task_all_cpu_backtrace=1 ima_policy=tcb
nf-conntrack-ftp.ports=20000 nf-conntrack-tftp.ports=20000
nf-conntrack-sip.ports=20000 nf-conntrack-irc.ports=20000
nf-conntrack-sane.ports=20000 binder.debug_mask=0
rcupdate.rcu_expedited=1 no_hash_pointers page_owner=on
sysctl.vm.nr_hugepages=4 sysctl.vm.nr_overcommit_hugepages=4
secretmem.enable=1 root=/dev/sda console=ttyS0 vsyscall=native
numa=fake=2 kvm-intel.nested=1 spec_store_bypass_disable=prctl nopcid
vivid.n_devs=16 vivid.multiplanar=1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2
netrom.nr_ndevs=16 rose.rose_ndevs=16 dummy_hcd.num=8
watchdog_thresh=55 workqueue.watchdog_thresh=140
sysctl.net.core.netdev_unregister_timeout_secs=140
BOOT_IMAGE=/boot/vmlinuz-5.16.0-rc5+
root=UUID=85844675-467a-4aac-9014-ad7e85e833bd ro crashkernel=256M
iomem=relaxed quiet nohz_full=2,3 rcu_nocbs=2,3
4)The test:
modprobe rcutorture nocbs_nthreads=8
Thanks Zhouyi
>
> BUG: KCSAN: data-race in rcu_nocb_cb_kthread / rcu_nocb_gp_kthread
>
> [34453.430323] read (marked) to 0xffff9dd1df26cb50 of 1 bytes by task 24 on cpu 13:
> [34453.431069] rcu_nocb_cb_kthread+0x18b/0x760
> [34453.431523] kthread+0x29b/0x2b0
> [34453.431864] ret_from_fork+0x22/0x30
> [34453.432245]
> [34453.432418] no locks held by rcuop/1/24.
> [34453.432823] irq event stamp: 13161844
> [34453.433208] hardirqs last enabled at (13161844): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [34453.434220] hardirqs last disabled at (13161843): [<ffffffff9c71b053>] _raw_spin_lock_irqsave+0x53/0xb0
> [34453.435129] softirqs last enabled at (13161839): [<ffffffff9b1ade6d>] local_bh_enable+0xd/0x30
> [34453.435979] softirqs last disabled at (13161837): [<ffffffff9b1ad5dd>] local_bh_disable+0xd/0x30
> [34453.436857]
> [34453.437020] write to 0xffff9dd1df26cb50 of 1 bytes by task 15 on cpu 3:
> [34453.437680] rcu_nocb_gp_kthread+0x3a3/0x1180
> [34453.438137] kthread+0x29b/0x2b0
> [34453.438482] ret_from_fork+0x22/0x30
> [34453.438861]
> [34453.439028] 1 lock held by rcuog/0/15:
> [34453.439414] #0: ffff9dd1df26cc70 (&rdp->nocb_lock){-.-.}-{2:2}, at: rcu_nocb_gp_kthread+0x2f2/0x1180
> [34453.440382] irq event stamp: 22823959
> [34453.440721] hardirqs last enabled at (22823958): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [34453.441892] hardirqs last disabled at (22823959): [<ffffffff9b1b1722>] rcu_nocb_gp_kthread+0x2d2/0x1180
> [34453.442831] softirqs last enabled at (22823695): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [34453.443721] softirqs last disabled at (22823672): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
>
> 0xffffffff811b275b is in rcu_nocb_cb_kthread (kernel/rcu/rcu_segcblist.h:71).
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
> 70 {
> 71 return READ_ONCE(rsclp->flags) & flags;
> 72 }
> 73
> 74 /*
> 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
>
> 0xffffffff811b17f3 is in rcu_nocb_gp_kthread (kernel/rcu/rcu_segcblist.h:59).
> 54 }
> 55
> 56 static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
> 57 int flags)
> 58 {
> 59 rsclp->flags |= flags;
> 60 }
> 61
> 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
> 63 int flags)
>
> ------------------------------------------------------------------------
>
> BUG: KCSAN: data-race in rcu_core / rcu_nocb_cb_kthread
>
> [35979.380848]
> [35979.380999] read (marked) to 0xffff9dd1df5ecb50 of 1 bytes by interrupt on cpu 15:
> [35979.381735] rcu_core+0x57/0x860
> [35979.382058] rcu_core_si+0x12/0x20
> [35979.382400] __do_softirq+0x1f9/0x37c
> [35979.382749] run_ksoftirqd+0x4c/0x80
> [35979.383097] smpboot_thread_fn+0x28b/0x390
> [35979.383492] kthread+0x29b/0x2b0
> [35979.383805] ret_from_fork+0x22/0x30
> [35979.384149]
> [35979.384298] no locks held by ksoftirqd/15/173.
> [35979.384711] irq event stamp: 2431400
> [35979.385049] hardirqs last enabled at (2431400): [<ffffffff9ca000de>] __do_softirq+0xde/0x37c
> [35979.385841] hardirqs last disabled at (2431398): [<ffffffff9b0c060e>] run_ksoftirqd+0x2e/0x80
> [35979.386631] softirqs last enabled at (2431394): [<ffffffff9b0c062c>] run_ksoftirqd+0x4c/0x80
> [35979.387429] softirqs last disabled at (2431399): [<ffffffff9b0c062c>] run_ksoftirqd+0x4c/0x80
> [35979.388215]
> [35979.388364] write to 0xffff9dd1df5ecb50 of 1 bytes by task 176 on cpu 10:
> [35979.388996] rcu_nocb_cb_kthread+0x479/0x760
> [35979.389427] kthread+0x29b/0x2b0
> [35979.389752] ret_from_fork+0x22/0x30
> [35979.390106]
> [35979.390260] 1 lock held by rcuop/15/176:
> [35979.390634] #0: ffff9dd1df5ecc70 (&rdp->nocb_lock){-.-.}-{2:2}, at: rcu_nocb_cb_kthread+0x2ff/0x760
>
> 0xffffffff811ad657 is in rcu_core (kernel/rcu/rcu_segcblist.h:71).
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
> 70 {
> 71 return READ_ONCE(rsclp->flags) & flags;
> 72 }
> 73
> 74 /*
> 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
>
> 0xffffffff811b2a49 is in rcu_nocb_cb_kthread (kernel/rcu/rcu_segcblist.h:65).
> 60 }
> 61
> 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
> 63 int flags)
> 64 {
> 65 rsclp->flags &= ~flags;
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
>
> ------------------------------------------------------------------------
>
> BUG: KCSAN: data-race in rcu_nocb_cb_kthread / rcu_rdp_is_offloaded
>
> [27570.512032] read (marked) to 0xffff9dd1df5ecb50 of 1 bytes by task 0 on cpu 15:
> [27570.512770] rcu_rdp_is_offloaded+0x63/0x1c0
> [27570.513222] rcu_needs_cpu+0x80/0xa0
> [27570.513601] tick_nohz_next_event+0x1d4/0x300
> [27570.514063] tick_nohz_idle_stop_tick+0x8f/0x3d0
> [27570.514532] do_idle+0x108/0x2b0
> [27570.514884] cpu_startup_entry+0x15/0x20
> [27570.515301] secondary_startup_64_no_verify+0xc3/0xcb
> [27570.515858]
> [27570.515997] write to 0xffff9dd1df5ecb50 of 1 bytes by task 176 on cpu 0:
> [27570.516577] rcu_nocb_cb_kthread+0x479/0x760
> [27570.517358] kthread+0x29b/0x2b0
> [27570.517712] ret_from_fork+0x22/0x30
> [27570.518121]
> [27570.518284] 1 lock held by rcuop/15/176:
> [27570.518691] #0: ffff9dd1df5ecc70 (&rdp->nocb_lock){-.-.}-{2:2}, at: rcu_nocb_cb_kthread+0x2ff/0x760
> [27570.519677] irq event stamp: 20494903
> [27570.520068] hardirqs last enabled at (20494902): [<ffffffff9b0bf40a>] __local_bh_enable_ip+0xca/0x120
> [27570.536982] hardirqs last disabled at (20494903): [<ffffffff9b1b28b7>] rcu_nocb_cb_kthread+0x2e7/0x760
> [27570.537913] softirqs last enabled at (20494901): [<ffffffff9b1ade6d>] local_bh_enable+0xd/0x30
> [27570.538697] softirqs last disabled at (20494899): [<ffffffff9b1ad5dd>] local_bh_disable+0xd/0x30
>
> rcu_rdp_is_offloaded+0x63
> 0xffffffff8119a543 is in rcu_rdp_is_offloaded (kernel/rcu/rcu_segcblist.h:71).
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
> 70 {
> 71 return READ_ONCE(rsclp->flags) & flags;
> 72 }
> 73
> 74 /*
> 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
>
> 0xffffffff811b2a49 is in rcu_nocb_cb_kthread (kernel/rcu/rcu_segcblist.h:65).
> 60 }
> 61
> 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
> 63 int flags)
> 64 {
> 65 rsclp->flags &= ~flags;
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
>
> ------------------------------------------------------------------------
>
> BUG: KCSAN: data-race in rcu_nocb_gp_kthread / rcu_segcblist_ready_cbs
>
> [22938.718032] read (marked) to 0xffff9dd1df5ecb50 of 1 bytes by interrupt on cpu 15:
> [22938.718839] rcu_segcblist_ready_cbs+0x1a/0x40
> [22938.719333] rcu_core+0x351/0x860
> [22938.719703] rcu_core_si+0x12/0x20
> [22938.720076] __do_softirq+0x1f9/0x37c
> [22938.720470] run_ksoftirqd+0x4c/0x80
> [22938.720879] smpboot_thread_fn+0x28b/0x390
> [22938.721339] kthread+0x29b/0x2b0
> [22938.721703] ret_from_fork+0x22/0x30
> [22938.722089]
> [22938.722252] no locks held by ksoftirqd/15/173.
> [22938.722719] irq event stamp: 1553879
> [22938.723104] hardirqs last enabled at (1553879): [<ffffffff9b1a7a8c>] note_gp_changes+0x1ac/0x1e0
> [22938.723996] hardirqs last disabled at (1553878): [<ffffffff9b1a793b>] note_gp_changes+0x5b/0x1e0
> [22938.724835] softirqs last enabled at (1553871): [<ffffffff9b0c062c>] run_ksoftirqd+0x4c/0x80
> [22938.736913] softirqs last disabled at (1553876): [<ffffffff9b0c062c>] run_ksoftirqd+0x4c/0x80
> [22938.737836]
> [22938.738013] write to 0xffff9dd1df5ecb50 of 1 bytes by task 154 on cpu 10:
> [22938.738725] rcu_nocb_gp_kthread+0x328/0x1180
> [22938.739210] kthread+0x29b/0x2b0
> [22938.739564] ret_from_fork+0x22/0x30
> [22938.739963]
> [22938.740141] 1 lock held by rcuog/12/154:
> [22938.740578] #0: ffff9dd1df5ecc70 (&rdp->nocb_lock){-.-.}-{2:2}, at: rcu_nocb_gp_kthread+0x2f2/0x1180
> [22938.741584] irq event stamp: 19190924
> [22938.741987] hardirqs last enabled at (19190923): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [22938.743018] hardirqs last disabled at (19190924): [<ffffffff9b1b1722>] rcu_nocb_gp_kthread+0x2d2/0x1180
> [22938.743991] softirqs last enabled at (19189530): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [22938.744919] softirqs last disabled at (19189525): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
>
> 0xffffffff811b397a is in rcu_segcblist_ready_cbs (kernel/rcu/rcu_segcblist.h:71).
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
> 70 {
> 71 return READ_ONCE(rsclp->flags) & flags;
> 72 }
> 73
> 74 /*
> 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
>
> 0xffffffff811b1778 is in rcu_nocb_gp_kthread (kernel/rcu/rcu_segcblist.h:65).
> 60 }
> 61
> 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
> 63 int flags)
> 64 {
> 65 rsclp->flags &= ~flags;
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
>
> ------------------------------------------------------------------------
>
> BUG: KCSAN: data-race in rcu_core / rcu_nocb_gp_kthread
>
> [17703.531588] read (marked) to 0xffff9dd1df4ecb50 of 1 bytes by interrupt on cpu 11:
> [17703.532349] rcu_segcblist_ready_cbs+0x1a/0x40
> [17703.532801] rcu_core+0x351/0x860
> [17703.533151] rcu_core_si+0x12/0x20
> [17703.533515] __do_softirq+0x1f9/0x37c
> [17703.533910] run_ksoftirqd+0x4c/0x80
> [17703.534296] smpboot_thread_fn+0x28b/0x390
> [17703.534741] kthread+0x29b/0x2b0
> [17703.535111] ret_from_fork+0x22/0x30
> [17703.535502]
> [17703.535671] no locks held by ksoftirqd/11/143.
> [17703.536162] irq event stamp: 1277315
> [17703.536541] hardirqs last enabled at (1277315): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [17703.537604] hardirqs last disabled at (1277314): [<ffffffff9b1a793b>] note_gp_changes+0x5b/0x1e0
> [17703.538666] softirqs last enabled at (1277307): [<ffffffff9b0c062c>] run_ksoftirqd+0x4c/0x80
> [17703.539560] softirqs last disabled at (1277312): [<ffffffff9b0c062c>] run_ksoftirqd+0x4c/0x80
> [17703.540445]
> [17703.540611] write to 0xffff9dd1df4ecb50 of 1 bytes by task 117 on cpu 0:
> [17703.541320] rcu_nocb_gp_kthread+0x328/0x1180
> [17703.541774] kthread+0x29b/0x2b0
> [17703.542154] ret_from_fork+0x22/0x30
> [17703.542544]
> [17703.542712] 1 lock held by rcuog/8/117:
> [17703.543126] #0: ffff9dd1df4ecc70 (&rdp->nocb_lock){-.-.}-{2:2}, at: rcu_nocb_gp_kthread+0x2f2/0x1180
> [17703.544068] irq event stamp: 14934462
> [17703.544454] hardirqs last enabled at (14934461): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [17703.545469] hardirqs last disabled at (14934462): [<ffffffff9b1b1722>] rcu_nocb_gp_kthread+0x2d2/0x1180
> [17703.546442] softirqs last enabled at (14934440): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [17703.547667] softirqs last disabled at (14934429): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
>
> 0xffffffff811b397a is in rcu_segcblist_ready_cbs (kernel/rcu/rcu_segcblist.h:71).
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
> 70 {
> 71 return READ_ONCE(rsclp->flags) & flags;
> 72 }
> 73
> 74 /*
> 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
>
> 0xffffffff811b1778 is in rcu_nocb_gp_kthread (kernel/rcu/rcu_segcblist.h:65).
> 60 }
> 61
> 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
> 63 int flags)
> 64 {
> 65 rsclp->flags &= ~flags;
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
>
> ------------------------------------------------------------------------
>
> BUG: KCSAN: data-race in rcu_nocb_cb_kthread / rcu_nocb_rdp_deoffload
>
> [25747.783445] read (marked) to 0xffff9dd1df5acb50 of 1 bytes by task 28476 on cpu 14:
> [25747.784193] rcu_nocb_rdp_deoffload+0x1a3/0x380
> [25747.784675] work_for_cpu_fn+0x32/0x50
> [25747.785071] process_one_work+0x54f/0x840
> [25747.785488] worker_thread+0x79c/0xa90
> [25747.785884] kthread+0x29b/0x2b0
> [25747.786230] ret_from_fork+0x22/0x30
> [25747.786611]
> [25747.786778] 2 locks held by kworker/14:2/28476:
> [25747.787244] #0: ffff9dd1c1054738 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x4d7/0x840
> [25747.788196] #1: ffffabe581ce3dd0 ((work_completion)(&wfc.work)){+.+.}-{0:0}, at: process_one_work+0x508/0x840
> [25747.789216] irq event stamp: 47423
> [25747.789563] hardirqs last enabled at (47423): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [25747.790533] hardirqs last disabled at (47422): [<ffffffff9c71b053>] _raw_spin_lock_irqsave+0x53/0xb0
> [25747.791450] softirqs last enabled at (47410): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [25747.792253] softirqs last disabled at (47405): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [25747.804153]
> [25747.804319] write to 0xffff9dd1df5acb50 of 1 bytes by task 169 on cpu 13:
> [25747.805254] rcu_nocb_cb_kthread+0x479/0x760
> [25747.805701] kthread+0x29b/0x2b0
> [25747.806156] ret_from_fork+0x22/0x30
> [25747.806581]
> [25747.806747] 1 lock held by rcuop/14/169:
> [25747.807344] #0: ffff9dd1df5acc70 (&rdp->nocb_lock){-.-.}-{2:2}, at: rcu_nocb_cb_kthread+0x2ff/0x760
> [25747.809333] irq event stamp: 19677863
> [25747.810093] hardirqs last enabled at (19677862): [<ffffffff9b0bf40a>] __local_bh_enable_ip+0xca/0x120
> [25747.820095] hardirqs last disabled at (19677863): [<ffffffff9b1b28b7>] rcu_nocb_cb_kthread+0x2e7/0x760
> [25747.822317] softirqs last enabled at (19677861): [<ffffffff9b1ade6d>] local_bh_enable+0xd/0x30
> [25747.824060] softirqs last disabled at (19677859): [<ffffffff9b1ad5dd>] local_bh_disable+0xd/0x30
>
> 0xffffffff811a5853 is in rcu_nocb_rdp_deoffload (kernel/rcu/rcu_segcblist.h:71).
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
> 70 {
> 71 return READ_ONCE(rsclp->flags) & flags;
> 72 }
> 73
> 74 /*
> 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
>
> 0xffffffff811b2a49 is in rcu_nocb_cb_kthread (kernel/rcu/rcu_segcblist.h:65).
> 60 }
> 61
> 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
> 63 int flags)
> 64 {
> 65 rsclp->flags &= ~flags;
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
>
> ------------------------------------------------------------------------
>
> BUG: KCSAN: data-race in rcu_nocb_gp_kthread / rcu_nocb_rdp_offload
>
> [15688.905747] read (marked) to 0xffff9dd1df56cb50 of 1 bytes by task 154 on cpu 9:
> [15688.906550] rcu_nocb_gp_kthread+0x237/0x1180
> [15688.907050] kthread+0x29b/0x2b0
> [15688.907421] ret_from_fork+0x22/0x30
> [15688.907824]
> [15688.908022] no locks held by rcuog/12/154.
> [15688.908468] irq event stamp: 13085451
> [15688.908865] hardirqs last enabled at (13085451): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [15688.909929] hardirqs last disabled at (13085450): [<ffffffff9c71b053>] _raw_spin_lock_irqsave+0x53/0xb0
> [15688.910949] softirqs last enabled at (13085112): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [15688.911908] softirqs last disabled at (13085107): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [15688.912849]
> [15688.913043] write to 0xffff9dd1df56cb50 of 1 bytes by task 16476 on cpu 13:
> [15688.913830] rcu_nocb_rdp_offload+0x24e/0x2c0
> [15688.914364] work_for_cpu_fn+0x32/0x50
> [15688.914805] process_one_work+0x54f/0x840
> [15688.915159] worker_thread+0x79c/0xa90
> [15688.915544] kthread+0x29b/0x2b0
> [15688.915907] ret_from_fork+0x22/0x30
> [15688.916325]
> [15688.916502] 3 locks held by kworker/13:0/16476:
> [15688.917016] #0: ffff9dd1c1054738 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x4d7/0x840
> [15688.918073] #1: ffffabe585163dd0 ((work_completion)(&wfc.work)){+.+.}-{0:0}, at: process_one_work+0x508/0x840
> [15688.919153] #2: ffff9dd1df56cc70 (&rdp->nocb_lock){-.-.}-{2:2}, at: rcu_nocb_rdp_offload+0x237/0x2c0
> [15688.920171] irq event stamp: 198553
> [15688.920539] hardirqs last enabled at (198552): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [15688.921577] hardirqs last disabled at (198553): [<ffffffff9b1a5d5e>] rcu_nocb_rdp_offload+0x21e/0x2c0
> [15688.922553] softirqs last enabled at (198341): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [15688.923462] softirqs last disabled at (198336): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
>
> 0xffffffff811b1687 is in rcu_nocb_gp_kthread (kernel/rcu/rcu_segcblist.h:71).
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
> 70 {
> 71 return READ_ONCE(rsclp->flags) & flags;
> 72 }
> 73
> 74 /*
> 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
>
> 0xffffffff811a5d8e is in rcu_nocb_rdp_offload (kernel/rcu/rcu_segcblist.h:65).
> 60 }
> 61
> 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
> 63 int flags)
> 64 {
> 65 rsclp->flags &= ~flags;
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
>
> ------------------------------------------------------------------------
>
> BUG: KCSAN: data-race in rcu_nocb_gp_kthread / rcu_rdp_is_offloaded
>
> [30067.322599] read (marked) to 0xffff9dd1df2ecb50 of 1 bytes by interrupt on cpu 3:
> [30067.323367] rcu_rdp_is_offloaded+0x63/0x1c0
> [30067.323929] rcu_sched_clock_irq+0x9d2/0x18d0
> [30067.324269] update_process_times+0xe9/0x110
> [30067.324692] tick_sched_timer+0xfd/0x170
> [30067.325195] __hrtimer_run_queues+0x28a/0x450
> [30067.325647] hrtimer_interrupt+0x234/0x6d0
> [30067.326519] __sysvec_apic_timer_interrupt+0xb8/0x1a0
> [30067.327039] sysvec_apic_timer_interrupt+0x9a/0xc0
> [30067.327557] asm_sysvec_apic_timer_interrupt+0x12/0x20
> [30067.328105] __tsan_read8+0x167/0x240
> [30067.328503] rcutorture_one_extend+0x211/0x590
> [30067.328994] rcu_torture_one_read+0x785/0xc90
> [30067.329444] rcu_torture_reader+0x19b/0x2e0
> [30067.330309] kthread+0x29b/0x2b0
> [30067.330654] ret_from_fork+0x22/0x30
> [30067.331075]
> [30067.331240] 2 locks held by rcu_torture_rea/93:
> [30067.331700] #0: ffffffff9d35c208 (rcu_read_lock_sched){....}-{1:2}, at: rcu_lock_acquire+0x11/0x40
> [30067.332708] #1: ffffffff9d35c238 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x11/0x40
> [30067.333656] irq event stamp: 2508045894
> [30067.334185] hardirqs last enabled at (2508045893): [<ffffffff9b0bf40a>] __local_bh_enable_ip+0xca/0x120
> [30067.335192] hardirqs last disabled at (2508045894): [<ffffffff9c70e1f7>] sysvec_apic_timer_interrupt+0x17/0xc0
> [30067.342726] softirqs last enabled at (2508045892): [<ffffffff9b1956fd>] local_bh_enable+0xd/0x30
> [30067.354637] softirqs last disabled at (2508045890): [<ffffffff9b1956cd>] local_bh_disable+0xd/0x30
> [30067.355483]
> [30067.355627] write to 0xffff9dd1df2ecb50 of 1 bytes by task 15 on cpu 0:
> [30067.356228] rcu_nocb_gp_kthread+0x3a3/0x1180
> [30067.356628] kthread+0x29b/0x2b0
> [30067.356936] ret_from_fork+0x22/0x30
> [30067.357284]
> [30067.357431] 1 lock held by rcuog/0/15:
> [30067.357873] #0: ffff9dd1df2ecc70 (&rdp->nocb_lock){-.-.}-{2:2}, at: rcu_nocb_gp_kthread+0x2f2/0x1180
> [30067.358746] irq event stamp: 19891260
> [30067.359093] hardirqs last enabled at (19891259): [<ffffffff9c71b23a>] _raw_spin_unlock_irqrestore+0x3a/0x70
> [30067.359998] hardirqs last disabled at (19891260): [<ffffffff9b1b1722>] rcu_nocb_gp_kthread+0x2d2/0x1180
> [30067.360860] softirqs last enabled at (19890706): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
> [30067.361694] softirqs last disabled at (19890697): [<ffffffff9b0bf844>] __irq_exit_rcu+0x64/0xc0
>
> 0xffffffff8119a543 is in rcu_rdp_is_offloaded (kernel/rcu/rcu_segcblist.h:71).
> 66 }
> 67
> 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
> 69 int flags)
> 70 {
> 71 return READ_ONCE(rsclp->flags) & flags;
> 72 }
> 73
> 74 /*
> 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
>
> 0xffffffff811b17f3 is in rcu_nocb_gp_kthread (kernel/rcu/rcu_segcblist.h:59).
> 54 }
> 55
> 56 static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
> 57 int flags)
> 58 {
> 59 rsclp->flags |= flags;
> 60 }
> 61
> 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
> 63 int flags)
