On Sun, Jul 18, 2021 at 11:03:51PM +0200, Oleksandr Natalenko wrote: > + stable@xxxxxxxxxxxxxxx > > On neděle 18. července 2021 23:01:24 CEST Oleksandr Natalenko wrote: > > Hello. > > > > On sobota 17. července 2021 22:22:08 CEST Chris Clayton wrote: > > > I checked the output from dmesg yesterday and found the following warning: > > > > > > [Fri Jul 16 09:15:29 2021] ------------[ cut here ]------------ > > > [Fri Jul 16 09:15:29 2021] WARNING: CPU: 11 PID: 2701 at > > > kernel/rcu/tree_plugin.h:359 rcu_note_context_switch+0x37/0x3d0 [Fri Jul > > > 16 I am not seeing a warning at line 359 of either v5.13.2 or v5.12.7. > > > 09:15:29 2021] Modules linked in: uas hidp rfcomm bnep xt_MASQUERADE > > > iptable_nat nf_nat xt_LOG nf_log_syslog xt_limit xt_multiport xt_conntrack > > > iptable_filter btusb btintel wmi_bmof uvcvideo videobuf2_vmalloc > > > videobuf2_memops videobuf2_v4l2 videobuf2_common coretemp hwmon > > > snd_hda_codec_hdmi x86_pkg_temp_thermal snd_hda_codec_realtek > > > snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg > > > snd_hda_codec snd_hwdep snd_hda_core i2c_i801 i2c_smbus iwlmvm mac80211 > > > iwlwifi i915 mei_me mei cfg80211 intel_lpss_pci intel_lpss wmi > > > nf_conntrack_ftp xt_helper nf_conntrack nf_defrag_ipv4 tun > > > [Fri Jul 16 09:15:29 2021] CPU: 11 PID: 2701 Comm: lpqd Not tainted 5.13.2 > > > #1 [Fri Jul 16 09:15:29 2021] Hardware name: Notebook > > > > > > NP50DE_DB /NP50DE_DB , BIOS 1.07.04 02/17/2020 > > > > > > [Fri Jul 16 09:15:29 2021] RIP: 0010:rcu_note_context_switch+0x37/0x3d0 > > > [Fri Jul 16 09:15:29 2021] Code: 02 00 e8 ec a0 6c 00 89 c0 65 4c 8b 2c 25 > > > 00 6d 01 00 48 03 1c c5 80 56 e1 b6 40 84 ed 75 0d 41 8b 95 04 03 00 00 85 > > > d2 7e 02 <0f> 0b 65 48 8b 04 25 00 6d 01 00 8b 80 04 03 00 00 85 c0 7e 0a > > > 41 [Fri Jul 16 09:15:29 2021] RSP: 0000:ffffb5d483837c70 EFLAGS: 00010002 > > > [Fri Jul 16 09:15:29 2021] RAX: 000000000000000b RBX: ffff9b77806e1d80 > > > RCX: > > > 0000000000000100 [Fri Jul 16 09:15:29 2021] RDX: 0000000000000001 RSI: > > > ffffffffb6d82ead RDI: ffffffffb6da5e4e [Fri Jul 16 09:15:29 2021] RBP: > > > 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 [Fri Jul 16 > > > 09:15:29 2021] R10: 000000067bce4fff R11: 0000000000000000 R12: > > > ffff9b77806e1100 [Fri Jul 16 09:15:29 2021] R13: ffff9b734a833a00 R14: > > > ffff9b734a833a00 R15: 0000000000000000 [Fri Jul 16 09:15:29 2021] FS: > > > 00007fccbfc5fe40(0000) GS:ffff9b77806c0000(0000) knlGS:0000000000000000 > > > [Fri Jul 16 09:15:29 2021] CS: 0010 DS: 0000 ES: 0000 CR0: > > > 0000000080050033 [Fri Jul 16 09:15:29 2021] CR2: 00007fccc2db7290 CR3: > > > 00000003fb0b8002 CR4: 00000000007706e0 [Fri Jul 16 09:15:29 2021] PKRU: > > > 55555554 > > > [Fri Jul 16 09:15:29 2021] Call Trace: > > > [Fri Jul 16 09:15:29 2021] __schedule+0x86/0x810 > > > [Fri Jul 16 09:15:29 2021] schedule+0x40/0xe0 > > > [Fri Jul 16 09:15:29 2021] io_schedule+0x3d/0x60 > > > [Fri Jul 16 09:15:29 2021] wait_on_page_bit_common+0x129/0x390 > > > [Fri Jul 16 09:15:29 2021] ? __filemap_set_wb_err+0x10/0x10 > > > [Fri Jul 16 09:15:29 2021] __lock_page_or_retry+0x13f/0x1d0 > > > [Fri Jul 16 09:15:29 2021] do_swap_page+0x335/0x5b0 > > > [Fri Jul 16 09:15:29 2021] __handle_mm_fault+0x444/0xb20 > > > [Fri Jul 16 09:15:29 2021] handle_mm_fault+0x5c/0x170 > > > [Fri Jul 16 09:15:29 2021] ? find_vma+0x5b/0x70 > > > [Fri Jul 16 09:15:29 2021] exc_page_fault+0x1ab/0x610 > > > [Fri Jul 16 09:15:29 2021] ? fpregs_assert_state_consistent+0x19/0x40 > > > [Fri Jul 16 09:15:29 2021] ? asm_exc_page_fault+0x8/0x30 > > > [Fri Jul 16 09:15:29 2021] asm_exc_page_fault+0x1e/0x30 > > > [Fri Jul 16 09:15:29 2021] RIP: 0033:0x7fccc2d3c520 > > > [Fri Jul 16 09:15:29 2021] Code: 68 4c 00 00 00 e9 20 fb ff ff ff 25 7a ad > > > 07 00 68 4d 00 00 00 e9 10 fb ff ff ff 25 72 ad 07 00 68 4e 00 00 00 e9 00 > > > fb ff ff <ff> 25 6a ad 07 00 68 4f 00 00 00 e9 f0 fa ff ff ff 25 62 ad 07 > > > 00 [Fri Jul 16 09:15:29 2021] RSP: 002b:00007ffebd529048 EFLAGS: 00010293 > > > [Fri Jul 16 09:15:29 2021] RAX: 0000000000000001 RBX: 00007fccc46e2890 > > > RCX: > > > 0000000000000010 [Fri Jul 16 09:15:29 2021] RDX: 0000000000000010 RSI: > > > 0000000000000000 RDI: 00007fccc46e2890 [Fri Jul 16 09:15:29 2021] RBP: > > > 000056264f1dd4a0 R08: 000056264f21aba0 R09: 000056264f1f58a0 [Fri Jul 16 > > > 09:15:29 2021] R10: 0000000000000007 R11: 0000000000000246 R12: > > > 000056264f21ac00 [Fri Jul 16 09:15:29 2021] R13: 000056264f1e0a30 R14: > > > 00007ffebd529080 R15: 00000000000dd87b [Fri Jul 16 09:15:29 2021] ---[ end > > > trace c8b06e067d8b0fc2 ]--- > > > > > > At the time the warning was issued I was creating a (weekly) backup of my > > > linux system (home-brewed based on the guidance from Linux From Scratch). > > > My backup routine is completed by copying the archive files (created with > > > dar) and a directory that contains about 7000 source and binary rpm files > > > to an external USB drive. I didn't spot the warning until later in the > > > day, > > > so I'm not sure exactly where I was in my backup process. > > > > > > I haven't seen this warning before. Consequently, I don;t know how easy > > > (or > > > otherwise) it is to reproduce. > > > > > > Let me know if I can provide any additional diagnostics, but please cc me > > > as I'm not subscribed. > > > > Confirming the same for me with v5.13.2, and cross-referencing another > > report [1] against v5.12.17. > > > > Also Cc'ing relevant people on this. > > > > Thanks. > > > > [1] > > https://lore.kernel.org/lkml/CAK2bqVK0Q9YcpakE7_Rc6nr-E4e2GnMOgi5jJj=_Eh_1k > > EHLHA@xxxxxxxxxxxxxx/ But this one does show this warning in v5.12.17: WARN_ON_ONCE(!preempt && rcu_preempt_depth() > 0); This is in rcu_note_context_switch(), and could be caused by something like a schedule() within an RCU read-side critical section. This would of course be RCU-usage bugs, given that you are not permitted to block within an RCU read-side critical section. I suggest checking the functions in the stack trace to see where the rcu_read_lock() is hiding. CONFIG_PROVE_LOCKING might also be helpful. Thanx, Paul
