Messages in this thread | | | Date | Fri, 23 Sep 2022 17:24:17 +0100 | From | Conor Dooley <> | Subject | [resend][bug] low-probability console lockups since 5.19 |
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Hey all,
Been bisecting a bug that is causing a boot failure in my CI & have ended up here.. The bug in question is a low(ish) probability lock up of the serial console, I would estimate about 1-in-5 chance on the boards I could actually trigger it on which it has taken me so long to realise that this was an actual problem. Thinking back on it, there were other failures that I would retroactively attribute to this problem too, but I had earlycon disabled and I chalked the hangs at "Starting kernel" down to pre-release hardware since the other boots in a CI job would not fail (we boot the same config multiple times), Silly me I guess!
In a boot failure (with earlycon & keep_bootcon enabled) I see the likes of [0]: [ 0.485063] NFS: Registering the id_resolver key type [ 0.491051] Key type id_resolver registered [ 0.495743] Key type id_legacy registered [ 0.500528] nfs4filelayout_init: NFSv4 File Layout Driver Registering... [ 0.508010] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering... [ 0.516857] 9p: Installing v9fs 9p2000 file system support [ 0.524032] NET: Registered PF_ALG protocol family [ 0.529562] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 247) [ 0.537817] io scheduler mq-deadline registered [ 0.542889] io scheduler kyber registered [ 0.559682] microchip-pcie 2000000000.pcie: host bridge /soc/pcie@2000000000 ranges: [ 0.568431] microchip-pcie 2000000000.pcie: MEM 0x2008000000..0x2087ffffff -> 0x0008000000 [ 0.635633] microchip-pcie 2000000000.pcie: axi read request error [ 0.642602] microchip-pcie 2000000000.pcie: axi read timeout [ 0.776630] microchip-pcie 2000000000.pcie: sec error in axi2pcie buffer [ 0.784133] microchip-pcie 2000000000.pcie: axi write request error [ 0.791100] microchip-pcie 2000000000.pcie: sec error in axi2pcie buffer [ 0.798543] microchip-pcie 2000000000.pcie: sec error in axi2pcie buffer [ 0.805981] microchip-pcie 2000000000.pcie: sec error in axi2pcie buffer [ 0.813421] microchip-pcie 2000000000.pcie: sec error in axi2pcie buffer [ 0.820859] microchip-pcie 2000000000.pcie: sec error in axi2pcie buffer [ 0.828295] microchip-pcie 2000000000.pcie: sec error in axi2pcie buffer [ 1.579668] Freeing initrd memory: 7316K
The sec error stuff is unrelated & happens on good boots too - although there are far fewer lines of "sec error" there [1] (excuse the message duplication from the bootcon).
I was able to bisect the behaviour to this set of reverts, but I have low confidence as to which commit specifically caused it - it's hard to know that doing 20+ reboots on every commmit I built is enough to make sure I did not make a mistake. I had initially started the bisection between v6.0-rc6 & v6.0-rc1, and that lead me down a sub-tree of net which is why the bisect log starts at a "random" commit as that merge commit was the one blamed by the inital bisection.
git bisect start # status: waiting for both good and bad commits # bad: [5e8379351dbde61ea383e514f0f9ecb2c047cf4e] Merge tag 'net-5.19-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net git bisect bad 5e8379351dbde61ea383e514f0f9ecb2c047cf4e # good: [4b0986a3613c92f4ec1bdc7f60ec66fea135991f] Linux 5.18 git bisect good 4b0986a3613c92f4ec1bdc7f60ec66fea135991f # good: [fbe86daca0ba878b04fa241b85e26e54d17d4229] Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi git bisect good fbe86daca0ba878b04fa241b85e26e54d17d4229 # good: [2b8c612c6102f751e6e3e1bd425f64e9d3d3f638] kernel/reboot: Fix powering off using a non-syscall code paths git bisect good 2b8c612c6102f751e6e3e1bd425f64e9d3d3f638 # good: [54c2cc79194c961a213c1d375fe3aa4165664cc4] Merge tag 'usb-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb git bisect good 54c2cc79194c961a213c1d375fe3aa4165664cc4 # skip: [8f7ac50c97d30ae5ae48da3b516510d05a67b9e5] Merge tag 'sound-5.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound git bisect skip 8f7ac50c97d30ae5ae48da3b516510d05a67b9e5 # good: [cdd85786f4b3b9273e4376e69aa95a2d71722764] x86/tdx: Clarify RIP adjustments in #VE handler git bisect good cdd85786f4b3b9273e4376e69aa95a2d71722764 # good: [8cc683833726912498130a0130fc3bd0d169ef59] Merge branch 'net-dp83822-fix-interrupt-floods' git bisect good 8cc683833726912498130a0130fc3bd0d169ef59 # bad: [0840a7914caa14315a3191178a9f72c742477860] Merge tag 'char-misc-5.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc git bisect bad 0840a7914caa14315a3191178a9f72c742477860 # bad: [38bc4ac431684498126f9baa3a530e5a132f0173] Merge tag 'drm-fixes-2022-06-24' of git://anongit.freedesktop.org/drm/drm git bisect bad 38bc4ac431684498126f9baa3a530e5a132f0173 # good: [399bd66e219e331976fe6fa6ab81a023c0c97870] Merge tag 'net-5.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net git bisect good 399bd66e219e331976fe6fa6ab81a023c0c97870 # bad: [a237cfd6b7469d6f5eeaa45f30128ab78b5281a5] Merge tag 'block-5.19-2022-06-24' of git://git.kernel.dk/linux-block git bisect bad a237cfd6b7469d6f5eeaa45f30128ab78b5281a5 # good: [92f20ff72066d8d7e2ffb655c2236259ac9d1c5d] Merge tag 'pm-5.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm git bisect good 92f20ff72066d8d7e2ffb655c2236259ac9d1c5d # bad: [598f2404879336277a4320ac5000394b873e049a] Merge tag 'io_uring-5.19-2022-06-24' of git://git.kernel.dk/linux-block git bisect bad 598f2404879336277a4320ac5000394b873e049a # good: [386e4fb6962b9f248a80f8870aea0870ca603e89] io_uring: use original request task for inflight tracking git bisect good 386e4fb6962b9f248a80f8870aea0870ca603e89 # good: [2d9ef940f89e0ab4fde7ba6f769d82f2a450c35a] Revert "printk: extend console_lock for per-console locking" git bisect good 2d9ef940f89e0ab4fde7ba6f769d82f2a450c35a # bad: [07a22b61946f0b80065b0ddcc703b715f84355f5] Revert "printk: add functions to prefer direct printing" git bisect bad 07a22b61946f0b80065b0ddcc703b715f84355f5 # bad: [5831788afb17b89c5b531fb60cbd798613ccbb63] Revert "printk: add kthread console printers" git bisect bad 5831788afb17b89c5b531fb60cbd798613ccbb63 # first bad commit: [5831788afb17b89c5b531fb60cbd798613ccbb63] Revert "printk: add kthread console printers"
On 5831788afb17 ("Revert "printk: add kthread console printers"") or on 07a22b61946f ("Revert "printk: add functions to prefer direct printing"") I was not able to reproduce the exact error conditions that I got on the current HEAD or any of the commits along my bisection, but instead I got something different [2]:
[ 0.471992] 9p: Installing v9fs 9p2000 file system support [ 0.479049] NET: Registered PF_ALG protocol family [ 0.484585] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 247) [ 0.492813] io scheduler mq-deadline registered [ 0.497871] io scheduler kyber registered [ 0.513472] microchip-pcie 2000000000.pcie: host bridge /soc/pcie@2000000000 ranges: [ 0.522194] microchip-pcie 2000000000.pcie: MEM 0x2008000000..0x2087ffffff -> 0x0008000000 [ 0.588518] microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer [ 0.596027] microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer [ 0.603467] microchip-pcie 2000000000.pcie: axi read request error [ 0.610322] microchip-pcie 2000000000.pcie: axi read timeout [ 0.616603] microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer [ 0.624025] microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer [ 0.631450] microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer [ 0.638877] microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer [ 0.646300] microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer [ 0.653725] microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer [ 1.516378] Freeing initrd memory: 7336K [ 5.591881] mc_event_handler: 667402 callbacks suppressed [ 5.591909] microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer [ 5.605290] microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer [ 5.612704] microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
<truncated>
[ 21.539878] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 21.546651] rcu: 0-...0: (1 GPs behind) idle=19f/1/0x4000000000000002 softirq=34/36 fqs=2626 [ 21.556177] (detected by 1, t=5256 jiffies, g=-1151, q=1143 ncpus=4) [ 21.563293] Task dump for CPU 0: [ 21.566860] task:swapper/0 state:R running task stack: 0 pid: 1 ppid: 0 flags:0x00000008 [ 21.577823] Call Trace:
Unfortunately I do not really have any more information than that for you, I am hoping that you (plural) could be of some help as to where I should start looking - although after spending every evening this week bisecting/setting up so that I could automate my bisection it'll be a few days before I could really focus on this again.
My system is an embedded RISC-V dev board (PolarFire SoC Icicle kit).
There is also a failing build in the ClangBuiltLinux CI [3] that is seeing similar symptoms, but I was unable to reproduce this problem doing 1000s of reboots of a known-bad commit in QEMU myself.
LMK if you need any more info, Conor.
[0] https://gist.githubusercontent.com/ConchuOD/575f4bfe3d68b9b32227740365b04401/raw/c69dfffd21183898edaeb223a9455ebc28edcf65/gistfile1.txt [1] https://gist.github.com/ConchuOD/575f4bfe3d68b9b32227740365b04401?permalink_comment_id=4313185#gistcomment-4313185 [2] https://gist.github.com/ConchuOD/575f4bfe3d68b9b32227740365b04401?permalink_comment_id=4313202#gistcomment-4313202 [3] https://github.com/ClangBuiltLinux/continuous-integration2/actions/runs/3090070308/jobs/4999131449#step:5:270
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