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cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG

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In order to avoid WARN/BUG from generating nested or even recursive
warnings, force rcu_is_watching() true during
WARN/lockdep_rcu_suspicious().

Notably things like unwinding the stack can trigger rcu_dereference()
warnings, which then triggers more unwinding which then triggers more
warnings etc..

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126151323.408156109@infradead.org
This commit is contained in:
Peter Zijlstra
2023-01-26 16:08:31 +01:00
committed by Ingo Molnar
parent 393e2ea30a
commit 5a5d7e9bad
4 changed files with 49 additions and 1 deletions
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5
kernel/panic.c
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@@ -34,6 +34,7 @@
#include <linux/ratelimit.h>
#include <linux/debugfs.h>
#include <linux/sysfs.h>
#include <linux/context_tracking.h>
#include <trace/events/error_report.h>
#include <asm/sections.h>
@@ -679,6 +680,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
void warn_slowpath_fmt(const char *file, int line, unsigned taint,
const char *fmt, ...)
{
bool rcu = warn_rcu_enter();
struct warn_args args;
pr_warn(CUT_HERE);
@@ -693,11 +695,13 @@ void warn_slowpath_fmt(const char *file, int line, unsigned taint,
va_start(args.args, fmt);
__warn(file, line, __builtin_return_address(0), taint, NULL, &args);
va_end(args.args);
warn_rcu_exit(rcu);
}
EXPORT_SYMBOL(warn_slowpath_fmt);
#else
void __warn_printk(const char *fmt, ...)
{
bool rcu = warn_rcu_enter();
va_list args;
pr_warn(CUT_HERE);
@@ -705,6 +709,7 @@ void __warn_printk(const char *fmt, ...)
va_start(args, fmt);
vprintk(fmt, args);
va_end(args);
warn_rcu_exit(rcu);
}
EXPORT_SYMBOL(__warn_printk);
#endif