From: Takashi Iwai <tiwai@suse.de>
To: amd-gfx@lists.freedesktop.org
Subject: kgdb_breakpoint() usage leads to kernel panic
Date: Thu, 22 Oct 2020 11:03:43 +0200 [thread overview]
Message-ID: <s5hy2jybpjk.wl-tiwai@suse.de> (raw)
Hi,
we recently stumbled on a kernel crash in amdgpu [*], and the kernel
messages indicated that it's from kgdb_breakpoint() call in
ASSERT_CRITICAL() macro.
Since CONFIG_KGDB=y is set on the openSUSE distro kernels, the
breakpoint is enabled even though CONFIG_DEBUG_KERNEL_DC=n, and this
leads to a kernel panic because of INT3. Unfortunately there is no
dynamical control to disable it.
I guess the kernel panic isn't intended for end-users, right? If so,
shouldn't we cover kgdb_breakpoint() in ASSERT_CRITICAL() also with
CONFIG_DEBUG_KERNEL_DC?
Also, taking a quick glance at the code, I noticed a few things:
- What's the difference of ASSERT() and ASSERT_CRITICAL()?
Why ASSERT() uses WARN_ON() and WARN_ON_ONCE() conditionally?
- I couldn't see CONFIG_HAVE_KGDB anywhere else. Is this superfluous?
- CONFIG_DEBUG_KERNEL_DC can have "depends on KGDB" in Kconfig.
Then the ifdefs can be much simplified.
[*] https://bugzilla.suse.com/show_bug.cgi?id=1177973
thanks,
Takashi
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next reply other threads:[~2020-10-22 9:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 9:03 Takashi Iwai [this message]
2020-10-23 7:45 ` kgdb_breakpoint() usage leads to kernel panic Takashi Iwai
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