Messages in this thread | | | Subject | Re: [PATCH 3/3] kernel/hung_task convert hung_task_panic boot parameter to sysctl | From | John Hubbard <> | Date | Mon, 30 Mar 2020 17:34:15 -0700 |
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On 3/30/20 10:43 AM, Kees Cook wrote: ... >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index 81ff626fc700..e0b8840404a1 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -1457,7 +1457,7 @@ >> [KNL] Should the hung task detector generate panics. >> Format: <integer> >> >> - A nonzero value instructs the kernel to panic when a >> + 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 >> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c >> index 97eb0b552bf8..77b1b844b02b 100644 >> --- a/fs/proc/proc_sysctl.c >> +++ b/fs/proc/proc_sysctl.c >> @@ -1743,6 +1743,7 @@ struct sysctl_alias { >> */ >> static const struct sysctl_alias sysctl_aliases[] = { >> {"numa_zonelist_order", "vm.numa_zonelist_order" },
Hi Vlastimil,
Maybe best to delete the above line? Because:
a) it was added as an example, and now that you have a real use case in this patch, the example is no longer required, and
b) numa_zonelist_order is deprecated, as a boot param. Adding support to it in this brand-new mechanism seems to be going a bit in the opposite direction of deprecation.
And, I don't think you really want all the sysctls to be enabled as boot params, right? Your comment right above sysctl_aliases[] (shown in patch 2) sort of indicates that only some items are meant to be both sysctl's and boot params. And that makes sense.
In fact, the sysctl_aliases[] is (or could be) effectively the whitelist that Luis Chamberlain was requesting in another thread. A whitelist makes good sense, for the reasons Luis listed. As such, keeping it limited to items that we want, seems like the way to go, IMHO.
thanks, -- John Hubbard NVIDIA
>> + {"hung_task_panic", "kernel.hung_task_panic" }, >> { } >> }; >> >> diff --git a/kernel/hung_task.c b/kernel/hung_task.c >> index 14a625c16cb3..b22b5eeab3cb 100644 >> --- a/kernel/hung_task.c >> +++ b/kernel/hung_task.c >> @@ -63,16 +63,6 @@ static struct task_struct *watchdog_task; >> unsigned int __read_mostly sysctl_hung_task_panic = >> CONFIG_BOOTPARAM_HUNG_TASK_PANIC_VALUE; >> >> -static int __init hung_task_panic_setup(char *str) >> -{ >> - int rc = kstrtouint(str, 0, &sysctl_hung_task_panic); >> - >> - if (rc) >> - return rc; >> - return 1; >> -} >> -__setup("hung_task_panic=", hung_task_panic_setup); >> - >> static int >> hung_task_panic(struct notifier_block *this, unsigned long event, void *ptr) >> { >> -- >> 2.25.1 >> >
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