Raised taint flag is never cleared. Following taint could be detected only via parsing kernel log messages which are different for each occasion. For repeatable taints like TAINT_MACHINE_CHECK, TAINT_BAD_PAGE, TAINT_DIE, TAINT_WARN, TAINT_LOCKUP it would be good to know count to see their rate. This patch adds sysctl with vector of counters. One for each taint flag. Counters are non-atomic in favor of simplicity. Exact count doesn't matter. Writing vector of zeroes resets counters: # tr 1-9 0 < /proc/sys/kernel/nr_taints > /proc/sys/kernel/nr_taints This is useful for detecting frequent problems with automatic monitoring. Also tests could use this for separating expected and unexpected taints. Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/lkml/157503370887.8187.1663761929323284758.stgit@buzz/ (v1) --- Documentation/admin-guide/sysctl/kernel.rst | 10 ++++++++++ Documentation/admin-guide/tainted-kernels.rst | 10 ++++++++++ include/linux/kernel.h | 1 + kernel/panic.c | 5 +++++ kernel/sysctl.c | 9 +++++++++ 5 files changed, 35 insertions(+) diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 8456c8ed0ca5..6250575bec9f 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -56,6 +56,7 @@ show up in /proc/sys/kernel: - msgmnb - msgmni - nmi_watchdog +- nr_taints ==> Documentation/admin-guide/tainted-kernels.rst - osrelease - ostype - overflowgid @@ -495,6 +496,15 @@ in a KVM virtual machine. This default can be overridden by adding:: to the guest kernel command line (see Documentation/admin-guide/kernel-parameters.rst). +nr_taints: +========== + +This shows vector of counters for taint flags. +Writing vector of zeroes resets counters. + +See Documentation/admin-guide/tainted-kernels.rst for more information. + + numa_balancing: =============== diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst index 13249240283c..2c5181d5e8ae 100644 --- a/Documentation/admin-guide/tainted-kernels.rst +++ b/Documentation/admin-guide/tainted-kernels.rst @@ -166,3 +166,13 @@ More detailed explanation for tainting produce extremely unusual kernel structure layouts (even performance pathological ones), which is important to know when debugging. Set at build time. + + +Taint flag counters +------------------- + +For detecting repeatedly set taint flags kernel counts them in sysctl: +``cat /proc/sys/kernel/nr_taints`` + +Writing vector of zeros resets counters but not taint flags itself: +``tr 1-9 0 < /proc/sys/kernel/nr_taints > /proc/sys/kernel/nr_taints`` diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 3554456b2d40..2e2c4d008ac1 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -597,6 +597,7 @@ struct taint_flag { }; extern const struct taint_flag taint_flags[TAINT_FLAGS_COUNT]; +extern int sysctl_nr_taints[TAINT_FLAGS_COUNT]; extern const char hex_asc[]; #define hex_asc_lo(x) hex_asc[((x) & 0x0f)] diff --git a/kernel/panic.c b/kernel/panic.c index a0ea0c6992b9..2e86387bbea0 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -39,6 +39,7 @@ int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; static unsigned long tainted_mask = IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0; +int sysctl_nr_taints[TAINT_FLAGS_COUNT]; static int pause_on_oops; static int pause_on_oops_flag; static DEFINE_SPINLOCK(pause_on_oops_lock); @@ -434,6 +435,10 @@ void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) pr_warn("Disabling lock debugging due to kernel taint\n"); set_bit(flag, &tainted_mask); + + /* proc_taint() could set unknown taint flag */ + if (flag < ARRAY_SIZE(sysctl_nr_taints)) + sysctl_nr_taints[flag]++; } EXPORT_SYMBOL(add_taint); diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 70665934d53e..21911a79305b 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -553,6 +553,15 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = proc_taint, }, + { + .procname = "nr_taints", + .data = &sysctl_nr_taints, + .maxlen = sizeof(sysctl_nr_taints), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ZERO, + }, { .procname = "sysctl_writes_strict", .data = &sysctl_writes_strict,
