Messages in this thread | | | Date | Mon, 18 Sep 2023 09:52:28 +0800 | Subject | Re: [: [bug report] WARNING: CPU: 121 PID: 93233 at fs/dcache.c:365 __dentry_kill+0x214/0x278] | From | Baokun Li <> |
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On 2023/9/17 17:26, Peter Zijlstra wrote: > On Sun, Sep 17, 2023 at 11:10:32AM +0200, Peter Zijlstra wrote: >> On Sat, Sep 16, 2023 at 02:55:47PM +0800, Baokun Li wrote: >>> On 2023/9/13 16:59, Yi Zhang wrote: >>>> The issue still can be reproduced on the latest linux tree[2]. >>>> To reproduce I need to run about 1000 times blktests block/001, and >>>> bisect shows it was introduced with commit[1], as it was not 100% >>>> reproduced, not sure if it's the culprit? >>>> >>>> >>>> [1] 9257959a6e5b locking/atomic: scripts: restructure fallback ifdeffery >>> Hello, everyone! >>> >>> We have confirmed that the merge-in of this patch caused hlist_bl_lock >>> (aka, bit_spin_lock) to fail, which in turn triggered the issue above. >>> [root@localhost ~]# insmod mymod.ko >>> [ 37.994787][ T621] >>> a = 725, b = 724 >>> [ 37.995313][ T621] ------------[ cut here ]------------ >>> [ 37.995951][ T621] kernel BUG at fs/mymod/mymod.c:42! >>> [r[ oo 3t7@.l996o4c61al]h[o s T6t21] ~ ]#Int ernal error: Oops - BUG: >>> 00000000f2000800 [#1] SMP >>> [ 37.997420][ T621] Modules linked in: mymod(E) >>> [ 37.997891][ T621] CPU: 9 PID: 621 Comm: bl_lock_thread2 Tainted: >>> G E 6.4.0-rc2-00034-g9257959a6e5b-dirty #117 >>> [ 37.999038][ T621] Hardware name: linux,dummy-virt (DT) >>> [ 37.999571][ T621] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS >>> BTYPE=--) >>> [ 38.000344][ T621] pc : increase_ab+0xcc/0xe70 [mymod] >>> [ 38.000882][ T621] lr : increase_ab+0xcc/0xe70 [mymod] >>> [ 38.001416][ T621] sp : ffff800008b4be40 >>> [ 38.001822][ T621] x29: ffff800008b4be40 x28: 0000000000000000 x27: >>> 0000000000000000 >>> [ 38.002605][ T621] x26: 0000000000000000 x25: 0000000000000000 x24: >>> 0000000000000000 >>> [ 38.003385][ T621] x23: ffffd9930c698190 x22: ffff800008a0ba38 x21: >>> 0000000000000001 >>> [ 38.004174][ T621] x20: ffffffffffffefff x19: ffffd9930c69a580 x18: >>> 0000000000000000 >>> [ 38.004955][ T621] x17: 0000000000000000 x16: ffffd9933011bd38 x15: >>> ffffffffffffffff >>> [ 38.005754][ T621] x14: 0000000000000000 x13: 205d313236542020 x12: >>> ffffd99332175b80 >>> [ 38.006538][ T621] x11: 0000000000000003 x10: 0000000000000001 x9 : >>> ffffd9933022a9d8 >>> [ 38.007325][ T621] x8 : 00000000000bffe8 x7 : c0000000ffff7fff x6 : >>> ffffd993320b5b40 >>> [ 38.008124][ T621] x5 : ffff0001f7d1c708 x4 : 0000000000000000 x3 : >>> 0000000000000000 >>> [ 38.008912][ T621] x2 : 0000000000000000 x1 : 0000000000000000 x0 : >>> 0000000000000015 >>> [ 38.009709][ T621] Call trace: >>> [ 38.010035][ T621] increase_ab+0xcc/0xe70 [mymod] >>> [ 38.010539][ T621] kthread+0xdc/0xf0 >>> [ 38.010927][ T621] ret_from_fork+0x10/0x20 >>> [ 38.011370][ T621] Code: 17ffffe0 90000020 91044000 9400000d (d4210000) >>> [ 38.012067][ T621] ---[ end trace 0000000000000000 ]--- >> Is this arm64 or something? You seem to have forgotten to mention what >> platform you're using. > Is that an LSE or LLSC arm64 ?
I'm not sure how to distinguish if it's LSE or LLSC, here's some info on the cpu:
$ cat /sys/devices/system/cpu/cpu0/regs/identification/midr_el1 0x00000000481fd010
$ lscpu Architecture: aarch64 Byte Order: Little Endian CPU(s): 96 On-line CPU(s) list: 0-95 Thread(s) per core: 1 Core(s) per socket: 48 Socket(s): 2 NUMA node(s): 4 Vendor ID: HiSilicon BIOS Vendor ID: HiSilicon Model: 0 Model name: Kunpeng-920 BIOS Model name: Kunpeng 920-4826 Stepping: 0x1 BogoMIPS: 200.00 L1d cache: 64K L1i cache: 64K L2 cache: 512K L3 cache: 49152K NUMA node0 CPU(s): 0-23 NUMA node1 CPU(s): 24-47 NUMA node2 CPU(s): 48-71 NUMA node3 CPU(s): 72-95 Flags: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma dcpop asimddp asimdfhm
> Anyway, it seems that ARM64 shouldn't be using the fallback as it does > everything itself. > > Mark, can you have a look please? At first glance the > atomic64_fetch_or_acquire() that's being used by generic bitops/lock.h > seems in order.. > We also suspect some implicit mechanism change in raw_atomic64_fetch_or_acquire. You can reproduce the problem with the above mod that can reproduce the problem to make it easier to locate. I can help reproduce it and grab some information if you can't reproduce it on your end.
-- With Best Regards, Baokun Li .
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