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Message-ID: <d492d12e4e5441a2b51c3415e865fa99@baidu.com> Date: Fri, 17 Oct 2025 02:09:10 +0000 From: "Li,Rongqing" <lirongqing@...du.com> To: Paul Menzel <pmenzel@...gen.mpg.de> CC: Andrew Morton <akpm@...ux-foundation.org>, Lance Yang <lance.yang@...ux.dev>, Masami Hiramatsu <mhiramat@...nel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>, "wireguard@...ts.zx2c4.com" <wireguard@...ts.zx2c4.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>, Andrew Jeffery <andrew@...econstruct.com.au>, Anshuman Khandual <anshuman.khandual@....com>, Arnd Bergmann <arnd@...db.de>, David Hildenbrand <david@...hat.com>, "Florian Wesphal" <fw@...len.de>, Jakub Kacinski <kuba@...nel.org>, "Jason A . Donenfeld" <jason@...c4.com>, Joel Granados <joel.granados@...nel.org>, "Joel Stanley" <joel@....id.au>, Jonathan Corbet <corbet@....net>, Kees Cook <kees@...nel.org>, Liam Howlett <liam.howlett@...cle.com>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, "Paul E . McKenney" <paulmck@...nel.org>, "Pawan Gupta" <pawan.kumar.gupta@...ux.intel.com>, Petr Mladek <pmladek@...e.com>, Phil Auld <pauld@...hat.com>, Randy Dunlap <rdunlap@...radead.org>, "Russell King" <linux@...linux.org.uk>, Shuah Khan <shuah@...nel.org>, Simon Horman <horms@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Steven Rostedt <rostedt@...dmis.org> Subject: RE: [外部邮件] Re: [PATCH][v4] hung_task: Panic when there are more than N hung tasks at the same time > > Am 15.10.25 um 08:36 schrieb lirongqing: > > From: Li RongQing <lirongqing@...du.com> > > > > Currently, when 'hung_task_panic' is enabled, the kernel panics > > immediately upon detecting the first hung task. However, some hung > > tasks are transient and allow system recovery, while persistent hangs > > should trigger a panic when accumulating beyond a threshold. > > > > Extend the 'hung_task_panic' sysctl to accept a threshold value > > specifying the number of hung tasks that must be detected before > > triggering a kernel panic. This provides finer control for > > environments where transient hangs may occur but persistent hangs > should be fatal. > > > > The sysctl now accepts: > > - 0: don't panic (maintains original behavior) > > - 1: panic on first hung task (maintains original behavior) > > - N > 1: panic after N hung tasks are detected in a single scan > > > > This maintains backward compatibility while providing flexibility for > > different hang scenarios. > > > > Signed-off-by: Li RongQing <lirongqing@...du.com> > > Cc: Andrew Jeffery <andrew@...econstruct.com.au> > > Cc: Anshuman Khandual <anshuman.khandual@....com> > > Cc: Arnd Bergmann <arnd@...db.de> > > Cc: David Hildenbrand <david@...hat.com> > > Cc: Florian Wesphal <fw@...len.de> > > Cc: Jakub Kacinski <kuba@...nel.org> > > Cc: Jason A. Donenfeld <jason@...c4.com> > > Cc: Joel Granados <joel.granados@...nel.org> > > Cc: Joel Stanley <joel@....id.au> > > Cc: Jonathan Corbet <corbet@....net> > > Cc: Kees Cook <kees@...nel.org> > > Cc: Lance Yang <lance.yang@...ux.dev> > > Cc: Liam Howlett <liam.howlett@...cle.com> > > Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com> > > Cc: "Masami Hiramatsu (Google)" <mhiramat@...nel.org> > > Cc: "Paul E . McKenney" <paulmck@...nel.org> > > Cc: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com> > > Cc: Petr Mladek <pmladek@...e.com> > > Cc: Phil Auld <pauld@...hat.com> > > Cc: Randy Dunlap <rdunlap@...radead.org> > > Cc: Russell King <linux@...linux.org.uk> > > Cc: Shuah Khan <shuah@...nel.org> > > Cc: Simon Horman <horms@...nel.org> > > Cc: Stanislav Fomichev <sdf@...ichev.me> > > Cc: Steven Rostedt <rostedt@...dmis.org> > > --- > > diff with v3: comments modification, suggested by Lance, Masami, Randy > > and Petr diff with v2: do not add a new sysctl, extend > > hung_task_panic, suggested by Kees Cook > > > > Documentation/admin-guide/kernel-parameters.txt | 20 > +++++++++++++------- > > Documentation/admin-guide/sysctl/kernel.rst | 9 +++++---- > > arch/arm/configs/aspeed_g5_defconfig | 2 +- > > kernel/configs/debug.config | 2 +- > > kernel/hung_task.c | 15 > ++++++++++----- > > lib/Kconfig.debug | 9 > +++++---- > > tools/testing/selftests/wireguard/qemu/kernel.config | 2 +- > > 7 files changed, 36 insertions(+), 23 deletions(-) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > > b/Documentation/admin-guide/kernel-parameters.txt > > index a51ab46..492f0bc 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -1992,14 +1992,20 @@ > > the added memory block itself do not be affected. > > > > hung_task_panic= > > - [KNL] Should the hung task detector generate panics. > > - Format: 0 | 1 > > + [KNL] Number of hung tasks to trigger kernel panic. > > + Format: <int> > > + > > + When set to a non-zero value, a kernel panic will be triggered > if > > + the number of detected hung tasks reaches this value. > > + > > + 0: don't panic > > + 1: panic immediately on first hung task > > + N: panic after N hung tasks are detected in a single scan > > > > - A value of 1 instructs the kernel to panic when a > > - hung task is detected. The default value is controlled > > - by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time > > - option. The value selected by this boot parameter can > > - be changed later by the kernel.hung_task_panic sysctl. > > + The default value is controlled by the > > + CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time option. > The value > > + selected by this boot parameter can be changed later by the > > + kernel.hung_task_panic sysctl. > > > > hvc_iucv= [S390] Number of z/VM IUCV hypervisor console > (HVC) > > terminal devices. Valid values: 0..8 diff --git > > a/Documentation/admin-guide/sysctl/kernel.rst > > b/Documentation/admin-guide/sysctl/kernel.rst > > index f3ee807..0065a55 100644 > > --- a/Documentation/admin-guide/sysctl/kernel.rst > > +++ b/Documentation/admin-guide/sysctl/kernel.rst > > @@ -397,13 +397,14 @@ a hung task is detected. > > hung_task_panic > > =============== > > > > -Controls the kernel's behavior when a hung task is detected. > > +When set to a non-zero value, a kernel panic will be triggered if the > > +number of hung tasks found during a single scan reaches this value. > > This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled. > > > > -= ================================================= > > += ======================================================= > > 0 Continue operation. This is the default behavior. > > -1 Panic immediately. > > -= ================================================= > > +N Panic when N hung tasks are found during a single scan. > > += ======================================================= > > > > > > hung_task_check_count > > […] > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index > > 3034e294..3976c90 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -1258,12 +1258,13 @@ config DEFAULT_HUNG_TASK_TIMEOUT > > Keeping the default should be fine in most cases. > > > > config BOOTPARAM_HUNG_TASK_PANIC > > - bool "Panic (Reboot) On Hung Tasks" > > + int "Number of hung tasks to trigger kernel panic" > > depends on DETECT_HUNG_TASK > > + default 0 > > help > > - Say Y here to enable the kernel to panic on "hung tasks", > > - which are bugs that cause the kernel to leave a task stuck > > - in uninterruptible "D" state. > > + When set to a non-zero value, a kernel panic will be triggered > > + if the number of hung tasks found during a single scan reaches > > + this value. > > > > The panic can be used in combination with panic_timeout, > > to cause the system to reboot automatically after a > Why not leave the sentence about the uninterruptible "D" state in there? > This seem to say a kernel bug to cause hung task, but it maybe hardware failure(or virtio backend bug); so I do not keep it > Also, it sounds like, some are actually using this in production. Maybe it > should be moved out of `Kconfig.debug` too? > I think hung task panic is a useful feature, it should move out of Kconfig.debug Thanks -Li > > Kind regards, > > Paul
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