Messages in this thread | | | Date | Mon, 13 Mar 2023 13:30:22 -0700 | From | Guenter Roeck <> | Subject | Re: Linux 6.3-rc2 |
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On Mon, Mar 13, 2023 at 11:21:44AM -0700, Linus Torvalds wrote: > On Mon, Mar 13, 2023 at 8:53 AM Guenter Roeck <linux@roeck-us.net> wrote: > > > > Warning backtraces in calls from ct_nmi_enter(), > > seen randomly. > > Hmm. > > I suspect this one is a bug in the warning, not in the kernel, > although I have no idea why it would have started happening now. > > This happens from an irq event, but that check is not *supposed* to > happen at all from interrupts: > > * We dont accurately track softirq state in e.g. > * hardirq contexts (such as on 4KSTACKS), so only > * check if not in hardirq contexts: > > but I think that the ct_nmi_enter() function was called before the > hardirq count had even been incremented. > > > Sample decoded stack trace: > > Hmm. That WARNING backtrace doesn't actually seem to follow the stack > chain, so it only shows the irq stack, not where the irq happened. > > > Seen if CONFIG_DEBUG_LOCK_ALLOC=y and CONFIG_CONTEXT_TRACKING_IDLE=y. > > It seems that rcu_read_lock_sched_held() can be true when entering an interrupt. > > > > The problem is not seen in v6.2, but occurs randomly on ToT with various > > arm emulations. > > Strange. I must be wrong about this being a race on the warning > itself, because that warning has been there for a long long time. > > Adding in some people who might have more of a clue. I'm thinking > Frederic and Paul might know what's up with the context tracking, but > I don't see why this would be arm-related or have started recently. > But I do note that PeterZ did some rcuidle tracing cleanups that do > end up affecting arm too. > > So adding PeterZ too. > > Original email with full details at > > https://lore.kernel.org/lkml/d915df60-d06b-47d4-8b47-8aa1bbc2aac7@roeck-us.net/ > > for added peeps. > > Anybody? >
It gets weird. Bisect log below. Reverting the identified patch does indeed seem to fix the problem, only I have no clue why this might be the case. The patch looks completely innocent to me. Yet, I can reliably reproduce the problem with v6.3-rc2, but at least so far I have not been able to reproduce it with commit f3dd0c53370 reverted (and I am trying on five different servers in parallel).
Guenter
--- # bad: [a5c95ca18a98d742d0a4a04063c32556b5b66378] Merge tag 'drm-next-2023-02-23' of git://anongit.freedesktop.org/drm/drm # good: [c9c3395d5e3dcc6daee66c6908354d47bf98cb0c] Linux 6.2 git bisect start 'a5c95ca18a98' 'v6.2' # good: [36289a03bcd3aabdf66de75cb6d1b4ee15726438] Merge tag 'v6.3-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 git bisect good 36289a03bcd3aabdf66de75cb6d1b4ee15726438 # bad: [0175ec3a28c695562a08fdccf73f2ec5ed744e2f] Merge tag 'regulator-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator git bisect bad 0175ec3a28c695562a08fdccf73f2ec5ed744e2f # good: [cb6b2e11a42decea2afc77df73ec7326db1ac25f] devlink: Fix memleak in health diagnose callback git bisect good cb6b2e11a42decea2afc77df73ec7326db1ac25f # good: [3365777a6a2243f1cca5a441f2c89002d16fc580] net: phy: marvell: Use the unlocked genphy_c45_ethtool_get_eee() git bisect good 3365777a6a2243f1cca5a441f2c89002d16fc580 # good: [700ed3bbb7a0bd5eeb805a2c2ba47a6d7b286745] ASoC: SOF: core/ipc4/mtl: Add support for PCM delay git bisect good 700ed3bbb7a0bd5eeb805a2c2ba47a6d7b286745 # good: [4d4266e3fd321fadb628ce02de641b129522c39c] page_pool: add a comment explaining the fragment counter usage git bisect good 4d4266e3fd321fadb628ce02de641b129522c39c # good: [76f5aaabce492aa6991c28c96bb78b00b05d06c5] ASoC: soc-ac97: Return correct error codes git bisect good 76f5aaabce492aa6991c28c96bb78b00b05d06c5 # good: [5661706efa200252d0e9fea02421b0a5857808c3] Merge branch 'topic/apple-gmux' into for-next git bisect good 5661706efa200252d0e9fea02421b0a5857808c3 # bad: [603ac530f13506e6ce5db4ab953ede4d292c5327] Merge tag 'regmap-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap git bisect bad 603ac530f13506e6ce5db4ab953ede4d292c5327 # good: [b60417a9f2b890a8094477b2204d4f73c535725e] selftest: fib_tests: Always cleanup before exit git bisect good b60417a9f2b890a8094477b2204d4f73c535725e # bad: [064d7dcf51a82b480e953a15cca47e5df0426502] Merge tag 'sound-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound git bisect bad 064d7dcf51a82b480e953a15cca47e5df0426502 # good: [5b7c4cabbb65f5c469464da6c5f614cbd7f730f2] Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next git bisect good 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 # good: [7933b90b42896f5b6596e6a829bb31c5121fc2a9] Merge branch 'for-linus' into for-next git bisect good 7933b90b42896f5b6596e6a829bb31c5121fc2a9 # bad: [f3dd0c53370e70c0f9b7e931bbec12916f3bb8cc] bpf: add missing header file include git bisect bad f3dd0c53370e70c0f9b7e931bbec12916f3bb8cc # first bad commit: [f3dd0c53370e70c0f9b7e931bbec12916f3bb8cc] bpf: add missing header file include
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