* [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address
@ 2024-12-31 5:02 kernel test robot
2024-12-31 7:16 ` Z qiang
0 siblings, 1 reply; 13+ messages in thread
From: kernel test robot @ 2024-12-31 5:02 UTC (permalink / raw)
To: Paul E. McKenney; +Cc: oe-lkp, lkp, rcu, oliver.sang
Hello,
kernel test robot noticed "BUG:unable_to_handle_page_fault_for_address" on:
commit: 9216c28c6a927fd20f116feed55bba025f18f401 ("srcu: Make SRCU readers use ->srcu_ctrs for counter selection")
https://github.com/paulmckrcu/linux dev.2024.12.24a
in testcase: rcutorture
version:
with following parameters:
runtime: 300s
test: default
torture_type: srcu
config: i386-randconfig-005-20241230
compiler: gcc-12
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
(please refer to attached dmesg/kmsg for entire log/backtrace)
+------------------------------------------------+------------+------------+
| | 2add2e88ea | 9216c28c6a |
+------------------------------------------------+------------+------------+
| BUG:unable_to_handle_page_fault_for_address | 0 | 6 |
| Oops | 0 | 6 |
| EIP:__srcu_read_lock | 0 | 6 |
| Kernel_panic-not_syncing:Fatal_exception | 0 | 6 |
+------------------------------------------------+------------+------------+
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com
[ 168.973150][ T628] BUG: unable to handle page fault for address: 2367a000
[ 168.973700][ T628] #PF: supervisor write access in kernel mode
[ 168.974809][ T628] #PF: error_code(0x0002) - not-present page
[ 168.975761][ T628] *pde = 00000000
[ 168.976236][ T628] Oops: Oops: 0002 [#1] PREEMPT SMP
[ 168.977052][ T628] CPU: 0 UID: 0 PID: 628 Comm: rcu_torture_wri Tainted: G T 6.13.0-rc2-00067-g9216c28c6a92 #1
[ 168.978867][ T628] Tainted: [T]=RANDSTRUCT
[ 168.979429][ T628] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
[ 168.980862][ T628] EIP: __srcu_read_lock (kernel/rcu/srcutree.c:749)
[ 168.981213][ T628] Code: 85 ff 74 0c e8 45 59 00 00 83 3b 00 74 02 0f 0b 5b 5e 5f 5d c3 8b 00 f0 83 44 24 fc 00 83 c0 07 83 e0 fc c3 55 89 e5 8b 50 04 <64> ff 02 f0 83 44 24 fc 00 2b 50 08 5d 89 d0 c1 f8 03 c3 55 89 e5
All code
========
0: 85 ff test %edi,%edi
2: 74 0c je 0x10
4: e8 45 59 00 00 call 0x594e
9: 83 3b 00 cmpl $0x0,(%rbx)
c: 74 02 je 0x10
e: 0f 0b ud2
10: 5b pop %rbx
11: 5e pop %rsi
12: 5f pop %rdi
13: 5d pop %rbp
14: c3 ret
15: 8b 00 mov (%rax),%eax
17: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp)
1d: 83 c0 07 add $0x7,%eax
20: 83 e0 fc and $0xfffffffc,%eax
23: c3 ret
24: 55 push %rbp
25: 89 e5 mov %esp,%ebp
27: 8b 50 04 mov 0x4(%rax),%edx
2a:* 64 ff 02 incl %fs:(%rdx) <-- trapping instruction
2d: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp)
33: 2b 50 08 sub 0x8(%rax),%edx
36: 5d pop %rbp
37: 89 d0 mov %edx,%eax
39: c1 f8 03 sar $0x3,%eax
3c: c3 ret
3d: 55 push %rbp
3e: 89 e5 mov %esp,%ebp
Code starting with the faulting instruction
===========================================
0: 64 ff 02 incl %fs:(%rdx)
3: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp)
9: 2b 50 08 sub 0x8(%rax),%edx
c: 5d pop %rbp
d: 89 d0 mov %edx,%eax
f: c1 f8 03 sar $0x3,%eax
12: c3 ret
13: 55 push %rbp
14: 89 e5 mov %esp,%ebp
[ 168.982540][ T628] EAX: ef0c8420 EBX: ef0c8420 ECX: e5e1e840 EDX: 00000000
[ 168.983022][ T628] ESI: ef0c919c EDI: 00000000 EBP: c75e9ee8 ESP: c75e9ee8
[ 168.983503][ T628] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010246
[ 168.984024][ T628] CR0: 80050033 CR2: 2367a000 CR3: 075f5000 CR4: 00040690
[ 168.984518][ T628] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[ 168.985008][ T628] DR6: fffe0ff0 DR7: 00000400
[ 168.985329][ T628] Call Trace:
[ 168.985571][ T628] ? show_regs (arch/x86/kernel/dumpstack.c:479 arch/x86/kernel/dumpstack.c:465)
[ 168.985877][ T628] ? __die_body (arch/x86/kernel/dumpstack.c:421)
[ 168.986185][ T628] ? __die (arch/x86/kernel/dumpstack.c:435)
[ 168.986466][ T628] ? page_fault_oops (arch/x86/mm/fault.c:715)
[ 168.986811][ T628] ? kernelmode_fixup_or_oops+0x50/0x58
[ 168.987273][ T628] ? __bad_area_nosemaphore+0x37/0x1d5
[ 168.987726][ T628] ? validate_chain (kernel/locking/lockdep.c:3819 kernel/locking/lockdep.c:3872)
[ 168.988058][ T628] ? bad_area_nosemaphore (arch/x86/mm/fault.c:835)
[ 168.988406][ T628] ? do_user_addr_fault (arch/x86/mm/fault.c:1280 (discriminator 1))
[ 168.988763][ T628] ? exc_page_fault (arch/x86/include/asm/irqflags.h:26 arch/x86/include/asm/irqflags.h:87 arch/x86/include/asm/irqflags.h:147 arch/x86/mm/fault.c:1489 arch/x86/mm/fault.c:1539)
[ 168.989110][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494)
[ 168.989472][ T628] ? handle_exception (arch/x86/entry/entry_32.S:1048)
[ 168.989800][ T628] ? siphash_4u64 (lib/siphash.c:203)
[ 168.990123][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494)
[ 168.990539][ T628] ? __srcu_read_lock (kernel/rcu/srcutree.c:749)
[ 168.990858][ T628] ? rcu_torture_barrier_init (kernel/rcu/rcutorture.c:3381) rcutorture
[ 168.991319][ T628] ? siphash_4u64 (lib/siphash.c:203)
[ 168.991618][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494)
[ 168.992021][ T628] ? __srcu_read_lock (kernel/rcu/srcutree.c:749)
[ 168.992340][ T628] srcu_read_lock (include/linux/srcu.h:165 include/linux/srcu.h:257) rcutorture
[ 168.992735][ T628] srcu_torture_read_lock (kernel/rcu/rcutorture.c:693) rcutorture
[ 168.993184][ T628] rcu_torture_writer (kernel/rcu/rcutorture.c:1528) rcutorture
[ 168.993615][ T628] ? _raw_spin_unlock_irqrestore (arch/x86/include/asm/irqflags.h:26 arch/x86/include/asm/irqflags.h:87 arch/x86/include/asm/irqflags.h:147 include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:194)
[ 168.994020][ T628] ? trace_hardirqs_on (kernel/trace/trace_preemptirq.c:80 (discriminator 13))
[ 168.994369][ T628] kthread (kernel/kthread.c:391)
[ 168.994647][ T628] ? rcu_torture_pipe_update (kernel/rcu/rcutorture.c:1447) rcutorture
[ 168.995108][ T628] ? list_del_init (include/linux/lockdep.h:248)
[ 168.995428][ T628] ret_from_fork (arch/x86/kernel/process.c:153)
[ 168.995735][ T628] ? list_del_init (include/linux/lockdep.h:248)
[ 168.996053][ T628] ret_from_fork_asm (arch/x86/entry/entry_32.S:737)
[ 168.996380][ T628] entry_INT80_32 (arch/x86/entry/entry_32.S:942)
[ 168.996692][ T628] Modules linked in: rcutorture(+) torture intel_rapl_msr intel_rapl_common iosf_mbi crc32c_intel aesni_intel input_leds led_class fuse
[ 168.997654][ T628] CR2: 000000002367a000
[ 168.997945][ T628] ---[ end trace 0000000000000000 ]---
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20241231/202412311203.ca7bddba-lkp@intel.com
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2024-12-31 5:02 [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address kernel test robot @ 2024-12-31 7:16 ` Z qiang 2024-12-31 16:19 ` Paul E. McKenney 0 siblings, 1 reply; 13+ messages in thread From: Z qiang @ 2024-12-31 7:16 UTC (permalink / raw) To: kernel test robot; +Cc: Paul E. McKenney, oe-lkp, lkp, rcu > > > > Hello, > > kernel test robot noticed "BUG:unable_to_handle_page_fault_for_address" on: > > commit: 9216c28c6a927fd20f116feed55bba025f18f401 ("srcu: Make SRCU readers use ->srcu_ctrs for counter selection") > https://github.com/paulmckrcu/linux dev.2024.12.24a > > in testcase: rcutorture > version: > with following parameters: > > runtime: 300s > test: default > torture_type: srcu > > > > config: i386-randconfig-005-20241230 > compiler: gcc-12 > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G > > (please refer to attached dmesg/kmsg for entire log/backtrace) > > > +------------------------------------------------+------------+------------+ > | | 2add2e88ea | 9216c28c6a | > +------------------------------------------------+------------+------------+ > | BUG:unable_to_handle_page_fault_for_address | 0 | 6 | > | Oops | 0 | 6 | > | EIP:__srcu_read_lock | 0 | 6 | > | Kernel_panic-not_syncing:Fatal_exception | 0 | 6 | > +------------------------------------------------+------------+------------+ > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot <oliver.sang@intel.com> > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > Please try the following modifications: diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index e85db7d5b364..7c7304dee645 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1999,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) for (i = 0; i < mod->num_srcu_structs; i++) { ssp = *(sspp++); ssp->sda = alloc_percpu(struct srcu_data); + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; if (WARN_ON_ONCE(!ssp->sda)) return -ENOMEM; } Thanks Zqiang > > [ 168.973150][ T628] BUG: unable to handle page fault for address: 2367a000 > [ 168.973700][ T628] #PF: supervisor write access in kernel mode > [ 168.974809][ T628] #PF: error_code(0x0002) - not-present page > [ 168.975761][ T628] *pde = 00000000 > [ 168.976236][ T628] Oops: Oops: 0002 [#1] PREEMPT SMP > [ 168.977052][ T628] CPU: 0 UID: 0 PID: 628 Comm: rcu_torture_wri Tainted: G T 6.13.0-rc2-00067-g9216c28c6a92 #1 > [ 168.978867][ T628] Tainted: [T]=RANDSTRUCT > [ 168.979429][ T628] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > [ 168.980862][ T628] EIP: __srcu_read_lock (kernel/rcu/srcutree.c:749) > [ 168.981213][ T628] Code: 85 ff 74 0c e8 45 59 00 00 83 3b 00 74 02 0f 0b 5b 5e 5f 5d c3 8b 00 f0 83 44 24 fc 00 83 c0 07 83 e0 fc c3 55 89 e5 8b 50 04 <64> ff 02 f0 83 44 24 fc 00 2b 50 08 5d 89 d0 c1 f8 03 c3 55 89 e5 > All code > ======== > 0: 85 ff test %edi,%edi > 2: 74 0c je 0x10 > 4: e8 45 59 00 00 call 0x594e > 9: 83 3b 00 cmpl $0x0,(%rbx) > c: 74 02 je 0x10 > e: 0f 0b ud2 > 10: 5b pop %rbx > 11: 5e pop %rsi > 12: 5f pop %rdi > 13: 5d pop %rbp > 14: c3 ret > 15: 8b 00 mov (%rax),%eax > 17: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp) > 1d: 83 c0 07 add $0x7,%eax > 20: 83 e0 fc and $0xfffffffc,%eax > 23: c3 ret > 24: 55 push %rbp > 25: 89 e5 mov %esp,%ebp > 27: 8b 50 04 mov 0x4(%rax),%edx > 2a:* 64 ff 02 incl %fs:(%rdx) <-- trapping instruction > 2d: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp) > 33: 2b 50 08 sub 0x8(%rax),%edx > 36: 5d pop %rbp > 37: 89 d0 mov %edx,%eax > 39: c1 f8 03 sar $0x3,%eax > 3c: c3 ret > 3d: 55 push %rbp > 3e: 89 e5 mov %esp,%ebp > > Code starting with the faulting instruction > =========================================== > 0: 64 ff 02 incl %fs:(%rdx) > 3: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp) > 9: 2b 50 08 sub 0x8(%rax),%edx > c: 5d pop %rbp > d: 89 d0 mov %edx,%eax > f: c1 f8 03 sar $0x3,%eax > 12: c3 ret > 13: 55 push %rbp > 14: 89 e5 mov %esp,%ebp > [ 168.982540][ T628] EAX: ef0c8420 EBX: ef0c8420 ECX: e5e1e840 EDX: 00000000 > [ 168.983022][ T628] ESI: ef0c919c EDI: 00000000 EBP: c75e9ee8 ESP: c75e9ee8 > [ 168.983503][ T628] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010246 > [ 168.984024][ T628] CR0: 80050033 CR2: 2367a000 CR3: 075f5000 CR4: 00040690 > [ 168.984518][ T628] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 > [ 168.985008][ T628] DR6: fffe0ff0 DR7: 00000400 > [ 168.985329][ T628] Call Trace: > [ 168.985571][ T628] ? show_regs (arch/x86/kernel/dumpstack.c:479 arch/x86/kernel/dumpstack.c:465) > [ 168.985877][ T628] ? __die_body (arch/x86/kernel/dumpstack.c:421) > [ 168.986185][ T628] ? __die (arch/x86/kernel/dumpstack.c:435) > [ 168.986466][ T628] ? page_fault_oops (arch/x86/mm/fault.c:715) > [ 168.986811][ T628] ? kernelmode_fixup_or_oops+0x50/0x58 > [ 168.987273][ T628] ? __bad_area_nosemaphore+0x37/0x1d5 > [ 168.987726][ T628] ? validate_chain (kernel/locking/lockdep.c:3819 kernel/locking/lockdep.c:3872) > [ 168.988058][ T628] ? bad_area_nosemaphore (arch/x86/mm/fault.c:835) > [ 168.988406][ T628] ? do_user_addr_fault (arch/x86/mm/fault.c:1280 (discriminator 1)) > [ 168.988763][ T628] ? exc_page_fault (arch/x86/include/asm/irqflags.h:26 arch/x86/include/asm/irqflags.h:87 arch/x86/include/asm/irqflags.h:147 arch/x86/mm/fault.c:1489 arch/x86/mm/fault.c:1539) > [ 168.989110][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494) > [ 168.989472][ T628] ? handle_exception (arch/x86/entry/entry_32.S:1048) > [ 168.989800][ T628] ? siphash_4u64 (lib/siphash.c:203) > [ 168.990123][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494) > [ 168.990539][ T628] ? __srcu_read_lock (kernel/rcu/srcutree.c:749) > [ 168.990858][ T628] ? rcu_torture_barrier_init (kernel/rcu/rcutorture.c:3381) rcutorture > [ 168.991319][ T628] ? siphash_4u64 (lib/siphash.c:203) > [ 168.991618][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494) > [ 168.992021][ T628] ? __srcu_read_lock (kernel/rcu/srcutree.c:749) > [ 168.992340][ T628] srcu_read_lock (include/linux/srcu.h:165 include/linux/srcu.h:257) rcutorture > [ 168.992735][ T628] srcu_torture_read_lock (kernel/rcu/rcutorture.c:693) rcutorture > [ 168.993184][ T628] rcu_torture_writer (kernel/rcu/rcutorture.c:1528) rcutorture > [ 168.993615][ T628] ? _raw_spin_unlock_irqrestore (arch/x86/include/asm/irqflags.h:26 arch/x86/include/asm/irqflags.h:87 arch/x86/include/asm/irqflags.h:147 include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:194) > [ 168.994020][ T628] ? trace_hardirqs_on (kernel/trace/trace_preemptirq.c:80 (discriminator 13)) > [ 168.994369][ T628] kthread (kernel/kthread.c:391) > [ 168.994647][ T628] ? rcu_torture_pipe_update (kernel/rcu/rcutorture.c:1447) rcutorture > [ 168.995108][ T628] ? list_del_init (include/linux/lockdep.h:248) > [ 168.995428][ T628] ret_from_fork (arch/x86/kernel/process.c:153) > [ 168.995735][ T628] ? list_del_init (include/linux/lockdep.h:248) > [ 168.996053][ T628] ret_from_fork_asm (arch/x86/entry/entry_32.S:737) > [ 168.996380][ T628] entry_INT80_32 (arch/x86/entry/entry_32.S:942) > [ 168.996692][ T628] Modules linked in: rcutorture(+) torture intel_rapl_msr intel_rapl_common iosf_mbi crc32c_intel aesni_intel input_leds led_class fuse > [ 168.997654][ T628] CR2: 000000002367a000 > [ 168.997945][ T628] ---[ end trace 0000000000000000 ]--- > > > The kernel config and materials to reproduce are available at: > https://download.01.org/0day-ci/archive/20241231/202412311203.ca7bddba-lkp@intel.com > > > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki > > ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2024-12-31 7:16 ` Z qiang @ 2024-12-31 16:19 ` Paul E. McKenney 2025-01-02 5:41 ` Oliver Sang 0 siblings, 1 reply; 13+ messages in thread From: Paul E. McKenney @ 2024-12-31 16:19 UTC (permalink / raw) To: Z qiang; +Cc: kernel test robot, oe-lkp, lkp, rcu On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > > > > > Hello, > > > > kernel test robot noticed "BUG:unable_to_handle_page_fault_for_address" on: > > > > commit: 9216c28c6a927fd20f116feed55bba025f18f401 ("srcu: Make SRCU readers use ->srcu_ctrs for counter selection") > > https://github.com/paulmckrcu/linux dev.2024.12.24a > > > > in testcase: rcutorture > > version: > > with following parameters: > > > > runtime: 300s > > test: default > > torture_type: srcu > > > > > > > > config: i386-randconfig-005-20241230 > > compiler: gcc-12 > > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G > > > > (please refer to attached dmesg/kmsg for entire log/backtrace) > > > > > > +------------------------------------------------+------------+------------+ > > | | 2add2e88ea | 9216c28c6a | > > +------------------------------------------------+------------+------------+ > > | BUG:unable_to_handle_page_fault_for_address | 0 | 6 | > > | Oops | 0 | 6 | > > | EIP:__srcu_read_lock | 0 | 6 | > > | Kernel_panic-not_syncing:Fatal_exception | 0 | 6 | > > +------------------------------------------------+------------+------------+ > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > the same patch/commit), kindly add following tags > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > Please try the following modifications: > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > index e85db7d5b364..7c7304dee645 100644 > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -1999,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) > for (i = 0; i < mod->num_srcu_structs; i++) { > ssp = *(sspp++); > ssp->sda = alloc_percpu(struct srcu_data); > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; This does look quite promising, so thank you for digging into this!!! Looking forward to seeing if it fixes the problem. ;-) Thanx, Paul > if (WARN_ON_ONCE(!ssp->sda)) > return -ENOMEM; > } > > > > Thanks > Zqiang > > > > > [ 168.973150][ T628] BUG: unable to handle page fault for address: 2367a000 > > [ 168.973700][ T628] #PF: supervisor write access in kernel mode > > [ 168.974809][ T628] #PF: error_code(0x0002) - not-present page > > [ 168.975761][ T628] *pde = 00000000 > > [ 168.976236][ T628] Oops: Oops: 0002 [#1] PREEMPT SMP > > [ 168.977052][ T628] CPU: 0 UID: 0 PID: 628 Comm: rcu_torture_wri Tainted: G T 6.13.0-rc2-00067-g9216c28c6a92 #1 > > [ 168.978867][ T628] Tainted: [T]=RANDSTRUCT > > [ 168.979429][ T628] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > > [ 168.980862][ T628] EIP: __srcu_read_lock (kernel/rcu/srcutree.c:749) > > [ 168.981213][ T628] Code: 85 ff 74 0c e8 45 59 00 00 83 3b 00 74 02 0f 0b 5b 5e 5f 5d c3 8b 00 f0 83 44 24 fc 00 83 c0 07 83 e0 fc c3 55 89 e5 8b 50 04 <64> ff 02 f0 83 44 24 fc 00 2b 50 08 5d 89 d0 c1 f8 03 c3 55 89 e5 > > All code > > ======== > > 0: 85 ff test %edi,%edi > > 2: 74 0c je 0x10 > > 4: e8 45 59 00 00 call 0x594e > > 9: 83 3b 00 cmpl $0x0,(%rbx) > > c: 74 02 je 0x10 > > e: 0f 0b ud2 > > 10: 5b pop %rbx > > 11: 5e pop %rsi > > 12: 5f pop %rdi > > 13: 5d pop %rbp > > 14: c3 ret > > 15: 8b 00 mov (%rax),%eax > > 17: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp) > > 1d: 83 c0 07 add $0x7,%eax > > 20: 83 e0 fc and $0xfffffffc,%eax > > 23: c3 ret > > 24: 55 push %rbp > > 25: 89 e5 mov %esp,%ebp > > 27: 8b 50 04 mov 0x4(%rax),%edx > > 2a:* 64 ff 02 incl %fs:(%rdx) <-- trapping instruction > > 2d: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp) > > 33: 2b 50 08 sub 0x8(%rax),%edx > > 36: 5d pop %rbp > > 37: 89 d0 mov %edx,%eax > > 39: c1 f8 03 sar $0x3,%eax > > 3c: c3 ret > > 3d: 55 push %rbp > > 3e: 89 e5 mov %esp,%ebp > > > > Code starting with the faulting instruction > > =========================================== > > 0: 64 ff 02 incl %fs:(%rdx) > > 3: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp) > > 9: 2b 50 08 sub 0x8(%rax),%edx > > c: 5d pop %rbp > > d: 89 d0 mov %edx,%eax > > f: c1 f8 03 sar $0x3,%eax > > 12: c3 ret > > 13: 55 push %rbp > > 14: 89 e5 mov %esp,%ebp > > [ 168.982540][ T628] EAX: ef0c8420 EBX: ef0c8420 ECX: e5e1e840 EDX: 00000000 > > [ 168.983022][ T628] ESI: ef0c919c EDI: 00000000 EBP: c75e9ee8 ESP: c75e9ee8 > > [ 168.983503][ T628] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010246 > > [ 168.984024][ T628] CR0: 80050033 CR2: 2367a000 CR3: 075f5000 CR4: 00040690 > > [ 168.984518][ T628] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 > > [ 168.985008][ T628] DR6: fffe0ff0 DR7: 00000400 > > [ 168.985329][ T628] Call Trace: > > [ 168.985571][ T628] ? show_regs (arch/x86/kernel/dumpstack.c:479 arch/x86/kernel/dumpstack.c:465) > > [ 168.985877][ T628] ? __die_body (arch/x86/kernel/dumpstack.c:421) > > [ 168.986185][ T628] ? __die (arch/x86/kernel/dumpstack.c:435) > > [ 168.986466][ T628] ? page_fault_oops (arch/x86/mm/fault.c:715) > > [ 168.986811][ T628] ? kernelmode_fixup_or_oops+0x50/0x58 > > [ 168.987273][ T628] ? __bad_area_nosemaphore+0x37/0x1d5 > > [ 168.987726][ T628] ? validate_chain (kernel/locking/lockdep.c:3819 kernel/locking/lockdep.c:3872) > > [ 168.988058][ T628] ? bad_area_nosemaphore (arch/x86/mm/fault.c:835) > > [ 168.988406][ T628] ? do_user_addr_fault (arch/x86/mm/fault.c:1280 (discriminator 1)) > > [ 168.988763][ T628] ? exc_page_fault (arch/x86/include/asm/irqflags.h:26 arch/x86/include/asm/irqflags.h:87 arch/x86/include/asm/irqflags.h:147 arch/x86/mm/fault.c:1489 arch/x86/mm/fault.c:1539) > > [ 168.989110][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494) > > [ 168.989472][ T628] ? handle_exception (arch/x86/entry/entry_32.S:1048) > > [ 168.989800][ T628] ? siphash_4u64 (lib/siphash.c:203) > > [ 168.990123][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494) > > [ 168.990539][ T628] ? __srcu_read_lock (kernel/rcu/srcutree.c:749) > > [ 168.990858][ T628] ? rcu_torture_barrier_init (kernel/rcu/rcutorture.c:3381) rcutorture > > [ 168.991319][ T628] ? siphash_4u64 (lib/siphash.c:203) > > [ 168.991618][ T628] ? pvclock_clocksource_read_nowd (arch/x86/mm/fault.c:1494) > > [ 168.992021][ T628] ? __srcu_read_lock (kernel/rcu/srcutree.c:749) > > [ 168.992340][ T628] srcu_read_lock (include/linux/srcu.h:165 include/linux/srcu.h:257) rcutorture > > [ 168.992735][ T628] srcu_torture_read_lock (kernel/rcu/rcutorture.c:693) rcutorture > > [ 168.993184][ T628] rcu_torture_writer (kernel/rcu/rcutorture.c:1528) rcutorture > > [ 168.993615][ T628] ? _raw_spin_unlock_irqrestore (arch/x86/include/asm/irqflags.h:26 arch/x86/include/asm/irqflags.h:87 arch/x86/include/asm/irqflags.h:147 include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:194) > > [ 168.994020][ T628] ? trace_hardirqs_on (kernel/trace/trace_preemptirq.c:80 (discriminator 13)) > > [ 168.994369][ T628] kthread (kernel/kthread.c:391) > > [ 168.994647][ T628] ? rcu_torture_pipe_update (kernel/rcu/rcutorture.c:1447) rcutorture > > [ 168.995108][ T628] ? list_del_init (include/linux/lockdep.h:248) > > [ 168.995428][ T628] ret_from_fork (arch/x86/kernel/process.c:153) > > [ 168.995735][ T628] ? list_del_init (include/linux/lockdep.h:248) > > [ 168.996053][ T628] ret_from_fork_asm (arch/x86/entry/entry_32.S:737) > > [ 168.996380][ T628] entry_INT80_32 (arch/x86/entry/entry_32.S:942) > > [ 168.996692][ T628] Modules linked in: rcutorture(+) torture intel_rapl_msr intel_rapl_common iosf_mbi crc32c_intel aesni_intel input_leds led_class fuse > > [ 168.997654][ T628] CR2: 000000002367a000 > > [ 168.997945][ T628] ---[ end trace 0000000000000000 ]--- > > > > > > The kernel config and materials to reproduce are available at: > > https://download.01.org/0day-ci/archive/20241231/202412311203.ca7bddba-lkp@intel.com > > > > > > > > -- > > 0-DAY CI Kernel Test Service > > https://github.com/intel/lkp-tests/wiki > > > > ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2024-12-31 16:19 ` Paul E. McKenney @ 2025-01-02 5:41 ` Oliver Sang 2025-01-02 18:55 ` Paul E. McKenney 0 siblings, 1 reply; 13+ messages in thread From: Oliver Sang @ 2025-01-02 5:41 UTC (permalink / raw) To: Paul E. McKenney; +Cc: Z qiang, oe-lkp, lkp, rcu, oliver.sang hi, Zqiang, hi, Paul, On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: [...] > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > the same patch/commit), kindly add following tags > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > Please try the following modifications: yes, the following modifications fix the issues we found for 9216c28c6a. thanks! Tested-by: kernel test robot <oliver.sang@intel.com> > > > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > index e85db7d5b364..7c7304dee645 100644 > > --- a/kernel/rcu/srcutree.c > > +++ b/kernel/rcu/srcutree.c > > @@ -1999,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) > > for (i = 0; i < mod->num_srcu_structs; i++) { > > ssp = *(sspp++); > > ssp->sda = alloc_percpu(struct srcu_data); > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > This does look quite promising, so thank you for digging into this!!! > > Looking forward to seeing if it fixes the problem. ;-) > > Thanx, Paul > > > if (WARN_ON_ONCE(!ssp->sda)) > > return -ENOMEM; > > } > > > > > > > > Thanks > > Zqiang ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-02 5:41 ` Oliver Sang @ 2025-01-02 18:55 ` Paul E. McKenney 2025-01-03 5:50 ` Z qiang 0 siblings, 1 reply; 13+ messages in thread From: Paul E. McKenney @ 2025-01-02 18:55 UTC (permalink / raw) To: Oliver Sang; +Cc: Z qiang, oe-lkp, lkp, rcu On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > hi, Zqiang, hi, Paul, > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > [...] > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > the same patch/commit), kindly add following tags > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > Please try the following modifications: > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > Tested-by: kernel test robot <oliver.sang@intel.com> Thank you, and I will apply this during my next rebase. Zqiang, unless you tell me otherwise, I will add your Co-developed-by and Signed-off-by. Either way, Happy Square New Year! Thanx, Paul > > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > > index e85db7d5b364..7c7304dee645 100644 > > > --- a/kernel/rcu/srcutree.c > > > +++ b/kernel/rcu/srcutree.c > > > @@ -1999,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) > > > for (i = 0; i < mod->num_srcu_structs; i++) { > > > ssp = *(sspp++); > > > ssp->sda = alloc_percpu(struct srcu_data); > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > This does look quite promising, so thank you for digging into this!!! > > > > Looking forward to seeing if it fixes the problem. ;-) > > > > Thanx, Paul > > > > > if (WARN_ON_ONCE(!ssp->sda)) > > > return -ENOMEM; > > > } > > > > > > > > > > > > Thanks > > > Zqiang ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-02 18:55 ` Paul E. McKenney @ 2025-01-03 5:50 ` Z qiang 2025-01-03 17:10 ` Paul E. McKenney 0 siblings, 1 reply; 13+ messages in thread From: Z qiang @ 2025-01-03 5:50 UTC (permalink / raw) To: paulmck; +Cc: Oliver Sang, oe-lkp, lkp, rcu > > On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > > hi, Zqiang, hi, Paul, > > > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > [...] > > > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > > the same patch/commit), kindly add following tags > > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > > > > Please try the following modifications: > > > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > Thank you, and I will apply this during my next rebase. > > Zqiang, unless you tell me otherwise, I will add your Co-developed-by > and Signed-off-by. > > Either way, Happy Square New Year! Thank you, Happy New Year! :) Thanks Zqiang > > Thanx, Paul > > > > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > > > index e85db7d5b364..7c7304dee645 100644 > > > > --- a/kernel/rcu/srcutree.c > > > > +++ b/kernel/rcu/srcutree.c > > > > @@ -1999,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) > > > > for (i = 0; i < mod->num_srcu_structs; i++) { > > > > ssp = *(sspp++); > > > > ssp->sda = alloc_percpu(struct srcu_data); > > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > > > This does look quite promising, so thank you for digging into this!!! > > > > > > Looking forward to seeing if it fixes the problem. ;-) > > > > > > Thanx, Paul > > > > > > > if (WARN_ON_ONCE(!ssp->sda)) > > > > return -ENOMEM; > > > > } > > > > > > > > > > > > > > > > Thanks > > > > Zqiang ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-03 5:50 ` Z qiang @ 2025-01-03 17:10 ` Paul E. McKenney 2025-01-06 3:24 ` Z qiang 0 siblings, 1 reply; 13+ messages in thread From: Paul E. McKenney @ 2025-01-03 17:10 UTC (permalink / raw) To: Z qiang; +Cc: Oliver Sang, oe-lkp, lkp, rcu On Fri, Jan 03, 2025 at 01:50:50PM +0800, Z qiang wrote: > > > > On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > > > hi, Zqiang, hi, Paul, > > > > > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > > > [...] > > > > > > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > > > the same patch/commit), kindly add following tags > > > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > > > > > > > Please try the following modifications: > > > > > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > Thank you, and I will apply this during my next rebase. > > > > Zqiang, unless you tell me otherwise, I will add your Co-developed-by > > and Signed-off-by. > > > > Either way, Happy Square New Year! > > Thank you, Happy New Year! :) And here you go! Please let me know of anything I missed. And thank you for saving me the time it would have taken to track this one down. ;-) Thanx, Paul ------------------------------------------------------------------------ commit 71c893e6d1857d1e4ea37aec557d734a560fdb39 Author: Paul E. McKenney <paulmck@kernel.org> Date: Thu Dec 19 16:08:54 2024 -0800 srcu: Make SRCU readers use ->srcu_ctrs for counter selection This commit causes SRCU readers to use ->srcu_ctrs for counter selection instead of ->srcu_idx. This takes another step towards array-indexing-free SRCU readers. [ paulmck: Apply kernel test robot feedback. ] Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: kernel test robot <oliver.sang@intel.com> diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index c794d599db5c1..1b01ced61a45b 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -101,6 +101,7 @@ struct srcu_usage { */ struct srcu_struct { unsigned int srcu_idx; /* Current rdr array element. */ + struct srcu_ctr __percpu *srcu_ctrp; struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ struct lockdep_map dep_map; struct srcu_usage *srcu_sup; /* Update-side data. */ @@ -167,6 +168,7 @@ struct srcu_struct { #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ { \ .sda = &pcpu_name, \ + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ } @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); */ static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) { - int idx; + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); - idx = READ_ONCE(ssp->srcu_idx) & 0x1; - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ + this_cpu_inc(scp->srcu_locks.counter); /* Y */ barrier(); /* Avoid leaking the critical section. */ - return idx; + return scp - &ssp->sda->srcu_ctrs[0]; } /* diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index d7ee2f345e192..3bf7f41ad72b8 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); ssp->srcu_sup->sda_is_static = is_static; - if (!is_static) + if (!is_static) { ssp->sda = alloc_percpu(struct srcu_data); + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; + } if (!ssp->sda) goto err_free_sup; init_srcu_struct_data(ssp); @@ -742,12 +744,11 @@ EXPORT_SYMBOL_GPL(__srcu_check_read_flavor); */ int __srcu_read_lock(struct srcu_struct *ssp) { - int idx; + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); - idx = READ_ONCE(ssp->srcu_idx) & 0x1; - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); + this_cpu_inc(scp->srcu_locks.counter); smp_mb(); /* B */ /* Avoid leaking the critical section. */ - return idx; + return scp - &ssp->sda->srcu_ctrs[0]; } EXPORT_SYMBOL_GPL(__srcu_read_lock); @@ -772,13 +773,11 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); */ int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) { - int idx; - struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); - idx = READ_ONCE(ssp->srcu_idx) & 0x1; - atomic_long_inc(&sdp->srcu_ctrs[idx].srcu_locks); + atomic_long_inc(&scp->srcu_locks); smp_mb__after_atomic(); /* B */ /* Avoid leaking the critical section. */ - return idx; + return scp - &ssp->sda->srcu_ctrs[0]; } EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); @@ -1152,6 +1151,8 @@ static void srcu_flip(struct srcu_struct *ssp) smp_mb(); /* E */ /* Pairs with B and C. */ WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1); // Flip the counter. + WRITE_ONCE(ssp->srcu_ctrp, + &ssp->sda->srcu_ctrs[!(ssp->srcu_ctrp - &ssp->sda->srcu_ctrs[0])]); /* * Ensure that if the updater misses an __srcu_read_unlock() @@ -1998,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) for (i = 0; i < mod->num_srcu_structs; i++) { ssp = *(sspp++); ssp->sda = alloc_percpu(struct srcu_data); + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; if (WARN_ON_ONCE(!ssp->sda)) return -ENOMEM; } ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-03 17:10 ` Paul E. McKenney @ 2025-01-06 3:24 ` Z qiang 2025-01-07 5:50 ` Paul E. McKenney 0 siblings, 1 reply; 13+ messages in thread From: Z qiang @ 2025-01-06 3:24 UTC (permalink / raw) To: paulmck; +Cc: Oliver Sang, oe-lkp, lkp, rcu > > On Fri, Jan 03, 2025 at 01:50:50PM +0800, Z qiang wrote: > > > > > > On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > > > > hi, Zqiang, hi, Paul, > > > > > > > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > > > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > > > > > [...] > > > > > > > > > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > > > > the same patch/commit), kindly add following tags > > > > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > > > > > > > > > > Please try the following modifications: > > > > > > > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > > > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > Thank you, and I will apply this during my next rebase. > > > > > > Zqiang, unless you tell me otherwise, I will add your Co-developed-by > > > and Signed-off-by. > > > > > > Either way, Happy Square New Year! > > > > Thank you, Happy New Year! :) > > And here you go! Please let me know of anything I missed. > > And thank you for saving me the time it would have taken to track > this one down. ;-) > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit 71c893e6d1857d1e4ea37aec557d734a560fdb39 > Author: Paul E. McKenney <paulmck@kernel.org> > Date: Thu Dec 19 16:08:54 2024 -0800 > > srcu: Make SRCU readers use ->srcu_ctrs for counter selection > > This commit causes SRCU readers to use ->srcu_ctrs for counter > selection instead of ->srcu_idx. This takes another step towards > array-indexing-free SRCU readers. > > [ paulmck: Apply kernel test robot feedback. ] > > Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> > Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > Tested-by: kernel test robot <oliver.sang@intel.com> > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > index c794d599db5c1..1b01ced61a45b 100644 > --- a/include/linux/srcutree.h > +++ b/include/linux/srcutree.h > @@ -101,6 +101,7 @@ struct srcu_usage { > */ > struct srcu_struct { > unsigned int srcu_idx; /* Current rdr array element. */ > + struct srcu_ctr __percpu *srcu_ctrp; > struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ > struct lockdep_map dep_map; > struct srcu_usage *srcu_sup; /* Update-side data. */ > @@ -167,6 +168,7 @@ struct srcu_struct { > #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ > { \ > .sda = &pcpu_name, \ > + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ > __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ > } > > @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); > */ > static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) > { > - int idx; > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ > + this_cpu_inc(scp->srcu_locks.counter); /* Y */ > barrier(); /* Avoid leaking the critical section. */ > - return idx; > + return scp - &ssp->sda->srcu_ctrs[0]; > } > > /* > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > index d7ee2f345e192..3bf7f41ad72b8 100644 > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); > INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); > ssp->srcu_sup->sda_is_static = is_static; > - if (!is_static) > + if (!is_static) { > ssp->sda = alloc_percpu(struct srcu_data); > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > + } > if (!ssp->sda) > goto err_free_sup; ssp->srcu_ctrp should be assigned a value under the condition that ssp->sda is allocated successfully. - if (!is_static) { + if (!is_static) ssp->sda = alloc_percpu(struct srcu_data); - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; - } if (!ssp->sda) goto err_free_sup; + if (!is_static) + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > init_srcu_struct_data(ssp); > @@ -742,12 +744,11 @@ EXPORT_SYMBOL_GPL(__srcu_check_read_flavor); > */ > int __srcu_read_lock(struct srcu_struct *ssp) > { > - int idx; > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); > + this_cpu_inc(scp->srcu_locks.counter); > smp_mb(); /* B */ /* Avoid leaking the critical section. */ > - return idx; > + return scp - &ssp->sda->srcu_ctrs[0]; > } > EXPORT_SYMBOL_GPL(__srcu_read_lock); > > @@ -772,13 +773,11 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); > */ > int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) > { > - int idx; > - struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); Should this be the case? struct srcu_ctr *scp = raw_cpu_ptr(ssp->srcu_ctrp); > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > - atomic_long_inc(&sdp->srcu_ctrs[idx].srcu_locks); > + atomic_long_inc(&scp->srcu_locks); > smp_mb__after_atomic(); /* B */ /* Avoid leaking the critical section. */ > - return idx; > + return scp - &ssp->sda->srcu_ctrs[0]; > } > EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); > > @@ -1152,6 +1151,8 @@ static void srcu_flip(struct srcu_struct *ssp) > smp_mb(); /* E */ /* Pairs with B and C. */ > > WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1); // Flip the counter. > + WRITE_ONCE(ssp->srcu_ctrp, > + &ssp->sda->srcu_ctrs[!(ssp->srcu_ctrp - &ssp->sda->srcu_ctrs[0])]); > > /* > * Ensure that if the updater misses an __srcu_read_unlock() > @@ -1998,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) > for (i = 0; i < mod->num_srcu_structs; i++) { > ssp = *(sspp++); > ssp->sda = alloc_percpu(struct srcu_data); > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > if (WARN_ON_ONCE(!ssp->sda)) > return -ENOMEM; - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; if (WARN_ON_ONCE(!ssp->sda)) return -ENOMEM; + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; Thanks Zqiang > } ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-06 3:24 ` Z qiang @ 2025-01-07 5:50 ` Paul E. McKenney 2025-01-07 9:49 ` Z qiang 0 siblings, 1 reply; 13+ messages in thread From: Paul E. McKenney @ 2025-01-07 5:50 UTC (permalink / raw) To: Z qiang; +Cc: Oliver Sang, oe-lkp, lkp, rcu On Mon, Jan 06, 2025 at 11:24:54AM +0800, Z qiang wrote: > > > > On Fri, Jan 03, 2025 at 01:50:50PM +0800, Z qiang wrote: > > > > > > > > On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > > > > > hi, Zqiang, hi, Paul, > > > > > > > > > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > > > > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > > > > > > > [...] > > > > > > > > > > > > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > > > > > the same patch/commit), kindly add following tags > > > > > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > > > > > > > > > > > > > Please try the following modifications: > > > > > > > > > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > > > > > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > Thank you, and I will apply this during my next rebase. > > > > > > > > Zqiang, unless you tell me otherwise, I will add your Co-developed-by > > > > and Signed-off-by. > > > > > > > > Either way, Happy Square New Year! > > > > > > Thank you, Happy New Year! :) > > > > And here you go! Please let me know of anything I missed. > > > > And thank you for saving me the time it would have taken to track > > this one down. ;-) > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > commit 71c893e6d1857d1e4ea37aec557d734a560fdb39 > > Author: Paul E. McKenney <paulmck@kernel.org> > > Date: Thu Dec 19 16:08:54 2024 -0800 > > > > srcu: Make SRCU readers use ->srcu_ctrs for counter selection > > > > This commit causes SRCU readers to use ->srcu_ctrs for counter > > selection instead of ->srcu_idx. This takes another step towards > > array-indexing-free SRCU readers. > > > > [ paulmck: Apply kernel test robot feedback. ] > > > > Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> > > Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > > index c794d599db5c1..1b01ced61a45b 100644 > > --- a/include/linux/srcutree.h > > +++ b/include/linux/srcutree.h > > @@ -101,6 +101,7 @@ struct srcu_usage { > > */ > > struct srcu_struct { > > unsigned int srcu_idx; /* Current rdr array element. */ > > + struct srcu_ctr __percpu *srcu_ctrp; > > struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ > > struct lockdep_map dep_map; > > struct srcu_usage *srcu_sup; /* Update-side data. */ > > @@ -167,6 +168,7 @@ struct srcu_struct { > > #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ > > { \ > > .sda = &pcpu_name, \ > > + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ > > __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ > > } > > > > @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); > > */ > > static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) > > { > > - int idx; > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ > > + this_cpu_inc(scp->srcu_locks.counter); /* Y */ > > barrier(); /* Avoid leaking the critical section. */ > > - return idx; > > + return scp - &ssp->sda->srcu_ctrs[0]; > > } > > > > /* > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > index d7ee2f345e192..3bf7f41ad72b8 100644 > > --- a/kernel/rcu/srcutree.c > > +++ b/kernel/rcu/srcutree.c > > @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > > atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); > > INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); > > ssp->srcu_sup->sda_is_static = is_static; > > - if (!is_static) > > + if (!is_static) { > > ssp->sda = alloc_percpu(struct srcu_data); > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > + } > > if (!ssp->sda) > > goto err_free_sup; > > ssp->srcu_ctrp should be assigned a value under the condition that > ssp->sda is allocated successfully. > > - if (!is_static) { > + if (!is_static) > ssp->sda = alloc_percpu(struct srcu_data); > - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > - } > if (!ssp->sda) > goto err_free_sup; > + if (!is_static) > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; It doesn't hurt to assign NULL to ssp->srcu_ctrp on allocation failure. Or am I missing something here? > > init_srcu_struct_data(ssp); > > @@ -742,12 +744,11 @@ EXPORT_SYMBOL_GPL(__srcu_check_read_flavor); > > */ > > int __srcu_read_lock(struct srcu_struct *ssp) > > { > > - int idx; > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); > > + this_cpu_inc(scp->srcu_locks.counter); > > smp_mb(); /* B */ /* Avoid leaking the critical section. */ > > - return idx; > > + return scp - &ssp->sda->srcu_ctrs[0]; > > } > > EXPORT_SYMBOL_GPL(__srcu_read_lock); > > > > @@ -772,13 +773,11 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); > > */ > > int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) > > { > > - int idx; > > - struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > Should this be the case? > > struct srcu_ctr *scp = raw_cpu_ptr(ssp->srcu_ctrp); Good catch! This is messed up. I am now thinking in terms of something like this: struct srcu_ctr *scp = this_cpu_ptr(READ_ONCE(ssp->srcu_ctrp)); Except that I broke the CONFIG_NEED_SRCU_NMI_SAFE=y case at some point, and need to fix that first. This commit works: c10edfa489eb ("srcu: Pull ->srcu_{un,}lock_count into a new srcu_ctr structure") I am now trying: 71c893e6d185 ("srcu: Make SRCU readers use ->srcu_ctrs for counter selection") The trick is to apply this patch: ------------------------------------------------------------------------ diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index 26ae869865a12..74809a083e2b5 100644 --- a/kernel/rcu/Kconfig +++ b/kernel/rcu/Kconfig @@ -66,7 +66,7 @@ config TREE_SRCU This option selects the full-fledged version of SRCU. config NEED_SRCU_NMI_SAFE - def_bool HAVE_NMI && !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !TINY_SRCU + def_bool HAVE_NMI && !TINY_SRCU config TASKS_RCU_GENERIC def_bool TASKS_RCU || TASKS_RUDE_RCU || TASKS_TRACE_RCU ------------------------------------------------------------------------ Or run some system with CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS=n. > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > - atomic_long_inc(&sdp->srcu_ctrs[idx].srcu_locks); > > + atomic_long_inc(&scp->srcu_locks); > > smp_mb__after_atomic(); /* B */ /* Avoid leaking the critical section. */ > > - return idx; > > + return scp - &ssp->sda->srcu_ctrs[0]; > > } > > EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); > > > > @@ -1152,6 +1151,8 @@ static void srcu_flip(struct srcu_struct *ssp) > > smp_mb(); /* E */ /* Pairs with B and C. */ > > > > WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1); // Flip the counter. > > + WRITE_ONCE(ssp->srcu_ctrp, > > + &ssp->sda->srcu_ctrs[!(ssp->srcu_ctrp - &ssp->sda->srcu_ctrs[0])]); > > > > /* > > * Ensure that if the updater misses an __srcu_read_unlock() > > @@ -1998,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) > > for (i = 0; i < mod->num_srcu_structs; i++) { > > ssp = *(sspp++); > > ssp->sda = alloc_percpu(struct srcu_data); > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > if (WARN_ON_ONCE(!ssp->sda)) > > return -ENOMEM; > > > - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > if (WARN_ON_ONCE(!ssp->sda)) > return -ENOMEM; > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; Again, the assigment does not hurt anything, but in this case I agree that your way is more clear, so I will use that. Thanx, Paul ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-07 5:50 ` Paul E. McKenney @ 2025-01-07 9:49 ` Z qiang 2025-01-08 4:26 ` Paul E. McKenney 0 siblings, 1 reply; 13+ messages in thread From: Z qiang @ 2025-01-07 9:49 UTC (permalink / raw) To: paulmck; +Cc: Oliver Sang, oe-lkp, lkp, rcu > > On Mon, Jan 06, 2025 at 11:24:54AM +0800, Z qiang wrote: > > > > > > On Fri, Jan 03, 2025 at 01:50:50PM +0800, Z qiang wrote: > > > > > > > > > > On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > > > > > > hi, Zqiang, hi, Paul, > > > > > > > > > > > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > > > > > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > > > > > > > > > [...] > > > > > > > > > > > > > > > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > > > > > > the same patch/commit), kindly add following tags > > > > > > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > > > > > > > > > > > > > > > > Please try the following modifications: > > > > > > > > > > > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > > > > > > > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > Thank you, and I will apply this during my next rebase. > > > > > > > > > > Zqiang, unless you tell me otherwise, I will add your Co-developed-by > > > > > and Signed-off-by. > > > > > > > > > > Either way, Happy Square New Year! > > > > > > > > Thank you, Happy New Year! :) > > > > > > And here you go! Please let me know of anything I missed. > > > > > > And thank you for saving me the time it would have taken to track > > > this one down. ;-) > > > > > > Thanx, Paul > > > > > > ------------------------------------------------------------------------ > > > > > > commit 71c893e6d1857d1e4ea37aec557d734a560fdb39 > > > Author: Paul E. McKenney <paulmck@kernel.org> > > > Date: Thu Dec 19 16:08:54 2024 -0800 > > > > > > srcu: Make SRCU readers use ->srcu_ctrs for counter selection > > > > > > This commit causes SRCU readers to use ->srcu_ctrs for counter > > > selection instead of ->srcu_idx. This takes another step towards > > > array-indexing-free SRCU readers. > > > > > > [ paulmck: Apply kernel test robot feedback. ] > > > > > > Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> > > > Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> > > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > > > index c794d599db5c1..1b01ced61a45b 100644 > > > --- a/include/linux/srcutree.h > > > +++ b/include/linux/srcutree.h > > > @@ -101,6 +101,7 @@ struct srcu_usage { > > > */ > > > struct srcu_struct { > > > unsigned int srcu_idx; /* Current rdr array element. */ > > > + struct srcu_ctr __percpu *srcu_ctrp; > > > struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ > > > struct lockdep_map dep_map; > > > struct srcu_usage *srcu_sup; /* Update-side data. */ > > > @@ -167,6 +168,7 @@ struct srcu_struct { > > > #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ > > > { \ > > > .sda = &pcpu_name, \ > > > + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ > > > __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ > > > } > > > > > > @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); > > > */ > > > static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) > > > { > > > - int idx; > > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ > > > + this_cpu_inc(scp->srcu_locks.counter); /* Y */ > > > barrier(); /* Avoid leaking the critical section. */ > > > - return idx; > > > + return scp - &ssp->sda->srcu_ctrs[0]; > > > } > > > > > > /* > > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > > index d7ee2f345e192..3bf7f41ad72b8 100644 > > > --- a/kernel/rcu/srcutree.c > > > +++ b/kernel/rcu/srcutree.c > > > @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > > > atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); > > > INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); > > > ssp->srcu_sup->sda_is_static = is_static; > > > - if (!is_static) > > > + if (!is_static) { > > > ssp->sda = alloc_percpu(struct srcu_data); > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > + } > > > if (!ssp->sda) > > > goto err_free_sup; > > > > ssp->srcu_ctrp should be assigned a value under the condition that > > ssp->sda is allocated successfully. > > > > - if (!is_static) { > > + if (!is_static) > > ssp->sda = alloc_percpu(struct srcu_data); > > - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > - } > > if (!ssp->sda) > > goto err_free_sup; > > + if (!is_static) > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > It doesn't hurt to assign NULL to ssp->srcu_ctrp on allocation failure. > > Or am I missing something here? No, I just think in case of failed allocation, there is no need to set srcu_ctrp. :) Thanks Zqiang > > > > init_srcu_struct_data(ssp); > > > @@ -742,12 +744,11 @@ EXPORT_SYMBOL_GPL(__srcu_check_read_flavor); > > > */ > > > int __srcu_read_lock(struct srcu_struct *ssp) > > > { > > > - int idx; > > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); > > > + this_cpu_inc(scp->srcu_locks.counter); > > > smp_mb(); /* B */ /* Avoid leaking the critical section. */ > > > - return idx; > > > + return scp - &ssp->sda->srcu_ctrs[0]; > > > } > > > EXPORT_SYMBOL_GPL(__srcu_read_lock); > > > > > > @@ -772,13 +773,11 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); > > > */ > > > int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) > > > { > > > - int idx; > > > - struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); > > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > Should this be the case? > > > > struct srcu_ctr *scp = raw_cpu_ptr(ssp->srcu_ctrp); > > Good catch! This is messed up. I am now thinking in terms of something > like this: > > struct srcu_ctr *scp = this_cpu_ptr(READ_ONCE(ssp->srcu_ctrp)); > > Except that I broke the CONFIG_NEED_SRCU_NMI_SAFE=y case at some point, > and need to fix that first. This commit works: > > c10edfa489eb ("srcu: Pull ->srcu_{un,}lock_count into a new srcu_ctr structure") > > I am now trying: > > 71c893e6d185 ("srcu: Make SRCU readers use ->srcu_ctrs for counter selection") > > The trick is to apply this patch: > > ------------------------------------------------------------------------ > diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig > index 26ae869865a12..74809a083e2b5 100644 > --- a/kernel/rcu/Kconfig > +++ b/kernel/rcu/Kconfig > @@ -66,7 +66,7 @@ config TREE_SRCU > This option selects the full-fledged version of SRCU. > > config NEED_SRCU_NMI_SAFE > - def_bool HAVE_NMI && !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !TINY_SRCU > + def_bool HAVE_NMI && !TINY_SRCU > > config TASKS_RCU_GENERIC > def_bool TASKS_RCU || TASKS_RUDE_RCU || TASKS_TRACE_RCU > ------------------------------------------------------------------------ > > Or run some system with CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS=n. > > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > > - atomic_long_inc(&sdp->srcu_ctrs[idx].srcu_locks); > > > + atomic_long_inc(&scp->srcu_locks); > > > smp_mb__after_atomic(); /* B */ /* Avoid leaking the critical section. */ > > > - return idx; > > > + return scp - &ssp->sda->srcu_ctrs[0]; > > > } > > > EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); > > > > > > @@ -1152,6 +1151,8 @@ static void srcu_flip(struct srcu_struct *ssp) > > > smp_mb(); /* E */ /* Pairs with B and C. */ > > > > > > WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1); // Flip the counter. > > > + WRITE_ONCE(ssp->srcu_ctrp, > > > + &ssp->sda->srcu_ctrs[!(ssp->srcu_ctrp - &ssp->sda->srcu_ctrs[0])]); > > > > > > /* > > > * Ensure that if the updater misses an __srcu_read_unlock() > > > @@ -1998,6 +1999,7 @@ static int srcu_module_coming(struct module *mod) > > > for (i = 0; i < mod->num_srcu_structs; i++) { > > > ssp = *(sspp++); > > > ssp->sda = alloc_percpu(struct srcu_data); > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > if (WARN_ON_ONCE(!ssp->sda)) > > > return -ENOMEM; > > > > > > - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > if (WARN_ON_ONCE(!ssp->sda)) > > return -ENOMEM; > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > Again, the assigment does not hurt anything, but in this case I agree > that your way is more clear, so I will use that. > > Thanx, Paul ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-07 9:49 ` Z qiang @ 2025-01-08 4:26 ` Paul E. McKenney 2025-01-08 5:55 ` Z qiang 0 siblings, 1 reply; 13+ messages in thread From: Paul E. McKenney @ 2025-01-08 4:26 UTC (permalink / raw) To: Z qiang; +Cc: Oliver Sang, oe-lkp, lkp, rcu On Tue, Jan 07, 2025 at 05:49:42PM +0800, Z qiang wrote: > > > > On Mon, Jan 06, 2025 at 11:24:54AM +0800, Z qiang wrote: > > > > > > > > On Fri, Jan 03, 2025 at 01:50:50PM +0800, Z qiang wrote: > > > > > > > > > > > > On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > > > > > > > hi, Zqiang, hi, Paul, > > > > > > > > > > > > > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > > > > > > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > > > > > > > > > > > [...] > > > > > > > > > > > > > > > > > > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > > > > > > > the same patch/commit), kindly add following tags > > > > > > > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > Please try the following modifications: > > > > > > > > > > > > > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > > > > > > > > > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > > > Thank you, and I will apply this during my next rebase. > > > > > > > > > > > > Zqiang, unless you tell me otherwise, I will add your Co-developed-by > > > > > > and Signed-off-by. > > > > > > > > > > > > Either way, Happy Square New Year! > > > > > > > > > > Thank you, Happy New Year! :) > > > > > > > > And here you go! Please let me know of anything I missed. > > > > > > > > And thank you for saving me the time it would have taken to track > > > > this one down. ;-) > > > > > > > > Thanx, Paul > > > > > > > > ------------------------------------------------------------------------ > > > > > > > > commit 71c893e6d1857d1e4ea37aec557d734a560fdb39 > > > > Author: Paul E. McKenney <paulmck@kernel.org> > > > > Date: Thu Dec 19 16:08:54 2024 -0800 > > > > > > > > srcu: Make SRCU readers use ->srcu_ctrs for counter selection > > > > > > > > This commit causes SRCU readers to use ->srcu_ctrs for counter > > > > selection instead of ->srcu_idx. This takes another step towards > > > > array-indexing-free SRCU readers. > > > > > > > > [ paulmck: Apply kernel test robot feedback. ] > > > > > > > > Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> > > > > Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> > > > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > > > > index c794d599db5c1..1b01ced61a45b 100644 > > > > --- a/include/linux/srcutree.h > > > > +++ b/include/linux/srcutree.h > > > > @@ -101,6 +101,7 @@ struct srcu_usage { > > > > */ > > > > struct srcu_struct { > > > > unsigned int srcu_idx; /* Current rdr array element. */ > > > > + struct srcu_ctr __percpu *srcu_ctrp; > > > > struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ > > > > struct lockdep_map dep_map; > > > > struct srcu_usage *srcu_sup; /* Update-side data. */ > > > > @@ -167,6 +168,7 @@ struct srcu_struct { > > > > #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ > > > > { \ > > > > .sda = &pcpu_name, \ > > > > + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ > > > > __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ > > > > } > > > > > > > > @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); > > > > */ > > > > static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) > > > > { > > > > - int idx; > > > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > > > > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); > > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ > > > > + this_cpu_inc(scp->srcu_locks.counter); /* Y */ > > > > barrier(); /* Avoid leaking the critical section. */ > > > > - return idx; > > > > + return scp - &ssp->sda->srcu_ctrs[0]; > > > > } > > > > > > > > /* > > > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > > > index d7ee2f345e192..3bf7f41ad72b8 100644 > > > > --- a/kernel/rcu/srcutree.c > > > > +++ b/kernel/rcu/srcutree.c > > > > @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > > > > atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); > > > > INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); > > > > ssp->srcu_sup->sda_is_static = is_static; > > > > - if (!is_static) > > > > + if (!is_static) { > > > > ssp->sda = alloc_percpu(struct srcu_data); > > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > + } > > > > if (!ssp->sda) > > > > goto err_free_sup; > > > > > > ssp->srcu_ctrp should be assigned a value under the condition that > > > ssp->sda is allocated successfully. > > > > > > - if (!is_static) { > > > + if (!is_static) > > > ssp->sda = alloc_percpu(struct srcu_data); > > > - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > - } > > > if (!ssp->sda) > > > goto err_free_sup; > > > + if (!is_static) > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > It doesn't hurt to assign NULL to ssp->srcu_ctrp on allocation failure. > > > > Or am I missing something here? > > No, I just think in case of failed allocation, there is no need to set > srcu_ctrp. :) True enough, but you are adding an extra "if", which is not free from either an execution-time viewpoint (not an issue here) or from a complexity viewpoint. I am not ruling your change out, but neither am I convinced. Please see below for the current state, which passes light testing even given proper testing of _nmisafe(). Which I was failing to do before. Thoughts? Thanx, Paul ------------------------------------------------------------------------ commit e8964cf2179673adc54aae38b62361fd0fdf89ff Author: Paul E. McKenney <paulmck@kernel.org> Date: Thu Dec 19 16:08:54 2024 -0800 srcu: Make SRCU readers use ->srcu_ctrs for counter selection This commit causes SRCU readers to use ->srcu_ctrs for counter selection instead of ->srcu_idx. This takes another step towards array-indexing-free SRCU readers. [ paulmck: Apply kernel test robot feedback. ] Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: kernel test robot <oliver.sang@intel.com> diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index c794d599db5c1..1b01ced61a45b 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -101,6 +101,7 @@ struct srcu_usage { */ struct srcu_struct { unsigned int srcu_idx; /* Current rdr array element. */ + struct srcu_ctr __percpu *srcu_ctrp; struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ struct lockdep_map dep_map; struct srcu_usage *srcu_sup; /* Update-side data. */ @@ -167,6 +168,7 @@ struct srcu_struct { #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ { \ .sda = &pcpu_name, \ + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ } @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); */ static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) { - int idx; + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); - idx = READ_ONCE(ssp->srcu_idx) & 0x1; - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ + this_cpu_inc(scp->srcu_locks.counter); /* Y */ barrier(); /* Avoid leaking the critical section. */ - return idx; + return scp - &ssp->sda->srcu_ctrs[0]; } /* diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index d7ee2f345e192..308cc7b5098c5 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); ssp->srcu_sup->sda_is_static = is_static; - if (!is_static) + if (!is_static) { ssp->sda = alloc_percpu(struct srcu_data); + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; + } if (!ssp->sda) goto err_free_sup; init_srcu_struct_data(ssp); @@ -742,12 +744,11 @@ EXPORT_SYMBOL_GPL(__srcu_check_read_flavor); */ int __srcu_read_lock(struct srcu_struct *ssp) { - int idx; + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); - idx = READ_ONCE(ssp->srcu_idx) & 0x1; - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); + this_cpu_inc(scp->srcu_locks.counter); smp_mb(); /* B */ /* Avoid leaking the critical section. */ - return idx; + return scp - &ssp->sda->srcu_ctrs[0]; } EXPORT_SYMBOL_GPL(__srcu_read_lock); @@ -772,13 +773,12 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); */ int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) { - int idx; - struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); + struct srcu_ctr __percpu *scpp = READ_ONCE(ssp->srcu_ctrp); + struct srcu_ctr *scp = this_cpu_ptr(scpp); - idx = READ_ONCE(ssp->srcu_idx) & 0x1; - atomic_long_inc(&sdp->srcu_ctrs[idx].srcu_locks); + atomic_long_inc(&scp->srcu_locks); smp_mb__after_atomic(); /* B */ /* Avoid leaking the critical section. */ - return idx; + return scpp - &ssp->sda->srcu_ctrs[0]; } EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); @@ -1152,6 +1152,8 @@ static void srcu_flip(struct srcu_struct *ssp) smp_mb(); /* E */ /* Pairs with B and C. */ WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1); // Flip the counter. + WRITE_ONCE(ssp->srcu_ctrp, + &ssp->sda->srcu_ctrs[!(ssp->srcu_ctrp - &ssp->sda->srcu_ctrs[0])]); /* * Ensure that if the updater misses an __srcu_read_unlock() @@ -2000,6 +2002,7 @@ static int srcu_module_coming(struct module *mod) ssp->sda = alloc_percpu(struct srcu_data); if (WARN_ON_ONCE(!ssp->sda)) return -ENOMEM; + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; } return 0; } ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-08 4:26 ` Paul E. McKenney @ 2025-01-08 5:55 ` Z qiang 2025-01-08 15:05 ` Paul E. McKenney 0 siblings, 1 reply; 13+ messages in thread From: Z qiang @ 2025-01-08 5:55 UTC (permalink / raw) To: paulmck; +Cc: Oliver Sang, oe-lkp, lkp, rcu > > On Tue, Jan 07, 2025 at 05:49:42PM +0800, Z qiang wrote: > > > > > > On Mon, Jan 06, 2025 at 11:24:54AM +0800, Z qiang wrote: > > > > > > > > > > On Fri, Jan 03, 2025 at 01:50:50PM +0800, Z qiang wrote: > > > > > > > > > > > > > > On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > > > > > > > > hi, Zqiang, hi, Paul, > > > > > > > > > > > > > > > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > > > > > > > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > > > > > > > > > > > > > [...] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > > > > > > > > the same patch/commit), kindly add following tags > > > > > > > > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Please try the following modifications: > > > > > > > > > > > > > > > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > > > > > > > > > > > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > > > > > Thank you, and I will apply this during my next rebase. > > > > > > > > > > > > > > Zqiang, unless you tell me otherwise, I will add your Co-developed-by > > > > > > > and Signed-off-by. > > > > > > > > > > > > > > Either way, Happy Square New Year! > > > > > > > > > > > > Thank you, Happy New Year! :) > > > > > > > > > > And here you go! Please let me know of anything I missed. > > > > > > > > > > And thank you for saving me the time it would have taken to track > > > > > this one down. ;-) > > > > > > > > > > Thanx, Paul > > > > > > > > > > ------------------------------------------------------------------------ > > > > > > > > > > commit 71c893e6d1857d1e4ea37aec557d734a560fdb39 > > > > > Author: Paul E. McKenney <paulmck@kernel.org> > > > > > Date: Thu Dec 19 16:08:54 2024 -0800 > > > > > > > > > > srcu: Make SRCU readers use ->srcu_ctrs for counter selection > > > > > > > > > > This commit causes SRCU readers to use ->srcu_ctrs for counter > > > > > selection instead of ->srcu_idx. This takes another step towards > > > > > array-indexing-free SRCU readers. > > > > > > > > > > [ paulmck: Apply kernel test robot feedback. ] > > > > > > > > > > Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> > > > > > Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> > > > > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > > > > > index c794d599db5c1..1b01ced61a45b 100644 > > > > > --- a/include/linux/srcutree.h > > > > > +++ b/include/linux/srcutree.h > > > > > @@ -101,6 +101,7 @@ struct srcu_usage { > > > > > */ > > > > > struct srcu_struct { > > > > > unsigned int srcu_idx; /* Current rdr array element. */ > > > > > + struct srcu_ctr __percpu *srcu_ctrp; > > > > > struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ > > > > > struct lockdep_map dep_map; > > > > > struct srcu_usage *srcu_sup; /* Update-side data. */ > > > > > @@ -167,6 +168,7 @@ struct srcu_struct { > > > > > #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ > > > > > { \ > > > > > .sda = &pcpu_name, \ > > > > > + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ > > > > > __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ > > > > > } > > > > > > > > > > @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); > > > > > */ > > > > > static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) > > > > > { > > > > > - int idx; > > > > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > > > > > > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); > > > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > > > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ > > > > > + this_cpu_inc(scp->srcu_locks.counter); /* Y */ > > > > > barrier(); /* Avoid leaking the critical section. */ > > > > > - return idx; > > > > > + return scp - &ssp->sda->srcu_ctrs[0]; > > > > > } > > > > > > > > > > /* > > > > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > > > > index d7ee2f345e192..3bf7f41ad72b8 100644 > > > > > --- a/kernel/rcu/srcutree.c > > > > > +++ b/kernel/rcu/srcutree.c > > > > > @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > > > > > atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); > > > > > INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); > > > > > ssp->srcu_sup->sda_is_static = is_static; > > > > > - if (!is_static) > > > > > + if (!is_static) { > > > > > ssp->sda = alloc_percpu(struct srcu_data); > > > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > > + } > > > > > if (!ssp->sda) > > > > > goto err_free_sup; > > > > > > > > ssp->srcu_ctrp should be assigned a value under the condition that > > > > ssp->sda is allocated successfully. > > > > > > > > - if (!is_static) { > > > > + if (!is_static) > > > > ssp->sda = alloc_percpu(struct srcu_data); > > > > - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > - } > > > > if (!ssp->sda) > > > > goto err_free_sup; > > > > + if (!is_static) > > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > > > It doesn't hurt to assign NULL to ssp->srcu_ctrp on allocation failure. > > > > > > Or am I missing something here? > > > > No, I just think in case of failed allocation, there is no need to set > > srcu_ctrp. :) > > True enough, but you are adding an extra "if", which is not free > from either an execution-time viewpoint (not an issue here) or from a > complexity viewpoint. I am not ruling your change out, but neither am > I convinced. > > Please see below for the current state, which passes light testing even > given proper testing of _nmisafe(). Which I was failing to do before. > > Thoughts? > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit e8964cf2179673adc54aae38b62361fd0fdf89ff > Author: Paul E. McKenney <paulmck@kernel.org> > Date: Thu Dec 19 16:08:54 2024 -0800 > > srcu: Make SRCU readers use ->srcu_ctrs for counter selection > > This commit causes SRCU readers to use ->srcu_ctrs for counter > selection instead of ->srcu_idx. This takes another step towards > array-indexing-free SRCU readers. > > [ paulmck: Apply kernel test robot feedback. ] > > Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> > Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > Tested-by: kernel test robot <oliver.sang@intel.com> > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > index c794d599db5c1..1b01ced61a45b 100644 > --- a/include/linux/srcutree.h > +++ b/include/linux/srcutree.h > @@ -101,6 +101,7 @@ struct srcu_usage { > */ > struct srcu_struct { > unsigned int srcu_idx; /* Current rdr array element. */ > + struct srcu_ctr __percpu *srcu_ctrp; > struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ > struct lockdep_map dep_map; > struct srcu_usage *srcu_sup; /* Update-side data. */ > @@ -167,6 +168,7 @@ struct srcu_struct { > #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ > { \ > .sda = &pcpu_name, \ > + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ > __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ > } > > @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); > */ > static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) > { > - int idx; > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ > + this_cpu_inc(scp->srcu_locks.counter); /* Y */ > barrier(); /* Avoid leaking the critical section. */ > - return idx; > + return scp - &ssp->sda->srcu_ctrs[0]; > } > > /* > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > index d7ee2f345e192..308cc7b5098c5 100644 > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); > INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); > ssp->srcu_sup->sda_is_static = is_static; > - if (!is_static) > + if (!is_static) { > ssp->sda = alloc_percpu(struct srcu_data); > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > + } > if (!ssp->sda) > goto err_free_sup; > init_srcu_struct_data(ssp); > @@ -742,12 +744,11 @@ EXPORT_SYMBOL_GPL(__srcu_check_read_flavor); > */ > int __srcu_read_lock(struct srcu_struct *ssp) > { > - int idx; > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); > + this_cpu_inc(scp->srcu_locks.counter); > smp_mb(); /* B */ /* Avoid leaking the critical section. */ > - return idx; > + return scp - &ssp->sda->srcu_ctrs[0]; > } > EXPORT_SYMBOL_GPL(__srcu_read_lock); > > @@ -772,13 +773,12 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); > */ > int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) > { > - int idx; > - struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); > + struct srcu_ctr __percpu *scpp = READ_ONCE(ssp->srcu_ctrp); > + struct srcu_ctr *scp = this_cpu_ptr(scpp); Whether raw_cpu_ptr() should be used, otherwise it will appear: BUG: using smp_processor_id() in preemptible [00000000] code: init/1 [ 7.324304][ T1] caller is debug_smp_processor_id+0x1b/0x30 [ 7.324308][ T1] CPU: 0 UID: 0 PID: 1 Comm: init Not tainted 6.13.0-rc2-yoctodev-standard+ #99 10b660623b999b402f7cd2198fe7d4ebd36ef1d0 [ 7.324311][ T1] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 [ 7.324314][ T1] Call Trace: [ 7.324315][ T1] <TASK> [ 7.324319][ T1] dump_stack_lvl+0xbb/0xd0 [ 7.324326][ T1] dump_stack+0x14/0x20 [ 7.324330][ T1] check_preemption_disabled+0xc7/0xf0 [ 7.324340][ T1] debug_smp_processor_id+0x1b/0x30 [ 7.324343][ T1] __srcu_read_lock_nmisafe+0x39/0xd0 [ 7.324353][ T1] console_flush_all+0x18c/0xbf0 ........ Thanks Zqiang > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > - atomic_long_inc(&sdp->srcu_ctrs[idx].srcu_locks); > + atomic_long_inc(&scp->srcu_locks); > smp_mb__after_atomic(); /* B */ /* Avoid leaking the critical section. */ > - return idx; > + return scpp - &ssp->sda->srcu_ctrs[0]; > } > EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); > > @@ -1152,6 +1152,8 @@ static void srcu_flip(struct srcu_struct *ssp) > smp_mb(); /* E */ /* Pairs with B and C. */ > > WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1); // Flip the counter. > + WRITE_ONCE(ssp->srcu_ctrp, > + &ssp->sda->srcu_ctrs[!(ssp->srcu_ctrp - &ssp->sda->srcu_ctrs[0])]); > > /* > * Ensure that if the updater misses an __srcu_read_unlock() > @@ -2000,6 +2002,7 @@ static int srcu_module_coming(struct module *mod) > ssp->sda = alloc_percpu(struct srcu_data); > if (WARN_ON_ONCE(!ssp->sda)) > return -ENOMEM; > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > } > return 0; > } ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address 2025-01-08 5:55 ` Z qiang @ 2025-01-08 15:05 ` Paul E. McKenney 0 siblings, 0 replies; 13+ messages in thread From: Paul E. McKenney @ 2025-01-08 15:05 UTC (permalink / raw) To: Z qiang; +Cc: Oliver Sang, oe-lkp, lkp, rcu On Wed, Jan 08, 2025 at 01:55:12PM +0800, Z qiang wrote: > > > > On Tue, Jan 07, 2025 at 05:49:42PM +0800, Z qiang wrote: > > > > > > > > On Mon, Jan 06, 2025 at 11:24:54AM +0800, Z qiang wrote: > > > > > > > > > > > > On Fri, Jan 03, 2025 at 01:50:50PM +0800, Z qiang wrote: > > > > > > > > > > > > > > > > On Thu, Jan 02, 2025 at 01:41:16PM +0800, Oliver Sang wrote: > > > > > > > > > hi, Zqiang, hi, Paul, > > > > > > > > > > > > > > > > > > On Tue, Dec 31, 2024 at 08:19:44AM -0800, Paul E. McKenney wrote: > > > > > > > > > > On Tue, Dec 31, 2024 at 03:16:25PM +0800, Z qiang wrote: > > > > > > > > > > > > > > > > > > [...] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > > > > > > > > > > the same patch/commit), kindly add following tags > > > > > > > > > > > > | Reported-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > > > | Closes: https://lore.kernel.org/oe-lkp/202412311203.ca7bddba-lkp@intel.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Please try the following modifications: > > > > > > > > > > > > > > > > > > yes, the following modifications fix the issues we found for 9216c28c6a. thanks! > > > > > > > > > > > > > > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > > > > > > > Thank you, and I will apply this during my next rebase. > > > > > > > > > > > > > > > > Zqiang, unless you tell me otherwise, I will add your Co-developed-by > > > > > > > > and Signed-off-by. > > > > > > > > > > > > > > > > Either way, Happy Square New Year! > > > > > > > > > > > > > > Thank you, Happy New Year! :) > > > > > > > > > > > > And here you go! Please let me know of anything I missed. > > > > > > > > > > > > And thank you for saving me the time it would have taken to track > > > > > > this one down. ;-) > > > > > > > > > > > > Thanx, Paul > > > > > > > > > > > > ------------------------------------------------------------------------ > > > > > > > > > > > > commit 71c893e6d1857d1e4ea37aec557d734a560fdb39 > > > > > > Author: Paul E. McKenney <paulmck@kernel.org> > > > > > > Date: Thu Dec 19 16:08:54 2024 -0800 > > > > > > > > > > > > srcu: Make SRCU readers use ->srcu_ctrs for counter selection > > > > > > > > > > > > This commit causes SRCU readers to use ->srcu_ctrs for counter > > > > > > selection instead of ->srcu_idx. This takes another step towards > > > > > > array-indexing-free SRCU readers. > > > > > > > > > > > > [ paulmck: Apply kernel test robot feedback. ] > > > > > > > > > > > > Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> > > > > > > Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> > > > > > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > > > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > > > > > > > > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > > > > > > index c794d599db5c1..1b01ced61a45b 100644 > > > > > > --- a/include/linux/srcutree.h > > > > > > +++ b/include/linux/srcutree.h > > > > > > @@ -101,6 +101,7 @@ struct srcu_usage { > > > > > > */ > > > > > > struct srcu_struct { > > > > > > unsigned int srcu_idx; /* Current rdr array element. */ > > > > > > + struct srcu_ctr __percpu *srcu_ctrp; > > > > > > struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ > > > > > > struct lockdep_map dep_map; > > > > > > struct srcu_usage *srcu_sup; /* Update-side data. */ > > > > > > @@ -167,6 +168,7 @@ struct srcu_struct { > > > > > > #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ > > > > > > { \ > > > > > > .sda = &pcpu_name, \ > > > > > > + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ > > > > > > __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ > > > > > > } > > > > > > > > > > > > @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); > > > > > > */ > > > > > > static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) > > > > > > { > > > > > > - int idx; > > > > > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > > > > > > > > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); > > > > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > > > > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ > > > > > > + this_cpu_inc(scp->srcu_locks.counter); /* Y */ > > > > > > barrier(); /* Avoid leaking the critical section. */ > > > > > > - return idx; > > > > > > + return scp - &ssp->sda->srcu_ctrs[0]; > > > > > > } > > > > > > > > > > > > /* > > > > > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > > > > > index d7ee2f345e192..3bf7f41ad72b8 100644 > > > > > > --- a/kernel/rcu/srcutree.c > > > > > > +++ b/kernel/rcu/srcutree.c > > > > > > @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > > > > > > atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); > > > > > > INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); > > > > > > ssp->srcu_sup->sda_is_static = is_static; > > > > > > - if (!is_static) > > > > > > + if (!is_static) { > > > > > > ssp->sda = alloc_percpu(struct srcu_data); > > > > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > > > + } > > > > > > if (!ssp->sda) > > > > > > goto err_free_sup; > > > > > > > > > > ssp->srcu_ctrp should be assigned a value under the condition that > > > > > ssp->sda is allocated successfully. > > > > > > > > > > - if (!is_static) { > > > > > + if (!is_static) > > > > > ssp->sda = alloc_percpu(struct srcu_data); > > > > > - ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > > - } > > > > > if (!ssp->sda) > > > > > goto err_free_sup; > > > > > + if (!is_static) > > > > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > > > > > > > It doesn't hurt to assign NULL to ssp->srcu_ctrp on allocation failure. > > > > > > > > Or am I missing something here? > > > > > > No, I just think in case of failed allocation, there is no need to set > > > srcu_ctrp. :) > > > > True enough, but you are adding an extra "if", which is not free > > from either an execution-time viewpoint (not an issue here) or from a > > complexity viewpoint. I am not ruling your change out, but neither am > > I convinced. > > > > Please see below for the current state, which passes light testing even > > given proper testing of _nmisafe(). Which I was failing to do before. > > > > Thoughts? > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > commit e8964cf2179673adc54aae38b62361fd0fdf89ff > > Author: Paul E. McKenney <paulmck@kernel.org> > > Date: Thu Dec 19 16:08:54 2024 -0800 > > > > srcu: Make SRCU readers use ->srcu_ctrs for counter selection > > > > This commit causes SRCU readers to use ->srcu_ctrs for counter > > selection instead of ->srcu_idx. This takes another step towards > > array-indexing-free SRCU readers. > > > > [ paulmck: Apply kernel test robot feedback. ] > > > > Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> > > Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > > index c794d599db5c1..1b01ced61a45b 100644 > > --- a/include/linux/srcutree.h > > +++ b/include/linux/srcutree.h > > @@ -101,6 +101,7 @@ struct srcu_usage { > > */ > > struct srcu_struct { > > unsigned int srcu_idx; /* Current rdr array element. */ > > + struct srcu_ctr __percpu *srcu_ctrp; > > struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ > > struct lockdep_map dep_map; > > struct srcu_usage *srcu_sup; /* Update-side data. */ > > @@ -167,6 +168,7 @@ struct srcu_struct { > > #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ > > { \ > > .sda = &pcpu_name, \ > > + .srcu_ctrp = &pcpu_name.srcu_ctrs[0], \ > > __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ > > } > > > > @@ -222,13 +224,12 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); > > */ > > static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) > > { > > - int idx; > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite()."); > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); /* Y */ > > + this_cpu_inc(scp->srcu_locks.counter); /* Y */ > > barrier(); /* Avoid leaking the critical section. */ > > - return idx; > > + return scp - &ssp->sda->srcu_ctrs[0]; > > } > > > > /* > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > index d7ee2f345e192..308cc7b5098c5 100644 > > --- a/kernel/rcu/srcutree.c > > +++ b/kernel/rcu/srcutree.c > > @@ -253,8 +253,10 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > > atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); > > INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu); > > ssp->srcu_sup->sda_is_static = is_static; > > - if (!is_static) > > + if (!is_static) { > > ssp->sda = alloc_percpu(struct srcu_data); > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > + } > > if (!ssp->sda) > > goto err_free_sup; > > init_srcu_struct_data(ssp); > > @@ -742,12 +744,11 @@ EXPORT_SYMBOL_GPL(__srcu_check_read_flavor); > > */ > > int __srcu_read_lock(struct srcu_struct *ssp) > > { > > - int idx; > > + struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > - this_cpu_inc(ssp->sda->srcu_ctrs[idx].srcu_locks.counter); > > + this_cpu_inc(scp->srcu_locks.counter); > > smp_mb(); /* B */ /* Avoid leaking the critical section. */ > > - return idx; > > + return scp - &ssp->sda->srcu_ctrs[0]; > > } > > EXPORT_SYMBOL_GPL(__srcu_read_lock); > > > > @@ -772,13 +773,12 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); > > */ > > int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) > > { > > - int idx; > > - struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); > > + struct srcu_ctr __percpu *scpp = READ_ONCE(ssp->srcu_ctrp); > > + struct srcu_ctr *scp = this_cpu_ptr(scpp); > > Whether raw_cpu_ptr() should be used, otherwise it will appear: > > BUG: using smp_processor_id() in preemptible [00000000] code: init/1 > [ 7.324304][ T1] caller is debug_smp_processor_id+0x1b/0x30 > [ 7.324308][ T1] CPU: 0 UID: 0 PID: 1 Comm: init Not tainted > 6.13.0-rc2-yoctodev-standard+ #99 > 10b660623b999b402f7cd2198fe7d4ebd36ef1d0 > [ 7.324311][ T1] Hardware name: QEMU Standard PC (Q35 + ICH9, > 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 > [ 7.324314][ T1] Call Trace: > [ 7.324315][ T1] <TASK> > [ 7.324319][ T1] dump_stack_lvl+0xbb/0xd0 > [ 7.324326][ T1] dump_stack+0x14/0x20 > [ 7.324330][ T1] check_preemption_disabled+0xc7/0xf0 > [ 7.324340][ T1] debug_smp_processor_id+0x1b/0x30 > [ 7.324343][ T1] __srcu_read_lock_nmisafe+0x39/0xd0 > [ 7.324353][ T1] console_flush_all+0x18c/0xbf0 > ........ You are quite right! Fixing, thank you! Ah, and the reason that the SRCU-P scenario did not catch this is that I didn't force CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS=y. Thanx, Paul > Thanks > Zqiang > > > > > - idx = READ_ONCE(ssp->srcu_idx) & 0x1; > > - atomic_long_inc(&sdp->srcu_ctrs[idx].srcu_locks); > > + atomic_long_inc(&scp->srcu_locks); > > smp_mb__after_atomic(); /* B */ /* Avoid leaking the critical section. */ > > - return idx; > > + return scpp - &ssp->sda->srcu_ctrs[0]; > > } > > EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); > > > > @@ -1152,6 +1152,8 @@ static void srcu_flip(struct srcu_struct *ssp) > > smp_mb(); /* E */ /* Pairs with B and C. */ > > > > WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1); // Flip the counter. > > + WRITE_ONCE(ssp->srcu_ctrp, > > + &ssp->sda->srcu_ctrs[!(ssp->srcu_ctrp - &ssp->sda->srcu_ctrs[0])]); > > > > /* > > * Ensure that if the updater misses an __srcu_read_unlock() > > @@ -2000,6 +2002,7 @@ static int srcu_module_coming(struct module *mod) > > ssp->sda = alloc_percpu(struct srcu_data); > > if (WARN_ON_ONCE(!ssp->sda)) > > return -ENOMEM; > > + ssp->srcu_ctrp = &ssp->sda->srcu_ctrs[0]; > > } > > return 0; > > } ^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2025-01-08 15:05 UTC | newest] Thread overview: 13+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2024-12-31 5:02 [paulmckrcu:dev.2024.12.24a] [srcu] 9216c28c6a: BUG:unable_to_handle_page_fault_for_address kernel test robot 2024-12-31 7:16 ` Z qiang 2024-12-31 16:19 ` Paul E. McKenney 2025-01-02 5:41 ` Oliver Sang 2025-01-02 18:55 ` Paul E. McKenney 2025-01-03 5:50 ` Z qiang 2025-01-03 17:10 ` Paul E. McKenney 2025-01-06 3:24 ` Z qiang 2025-01-07 5:50 ` Paul E. McKenney 2025-01-07 9:49 ` Z qiang 2025-01-08 4:26 ` Paul E. McKenney 2025-01-08 5:55 ` Z qiang 2025-01-08 15:05 ` Paul E. McKenney
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