The patch titled
lockdep: disable lock debugging when kernel state becomes untrusted
has been added to the -mm tree. Its filename is
disable-lock-debugging-when-kernel-state-becomes-untrusted.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: lockdep: disable lock debugging when kernel state becomes untrusted
From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Disable lockdep debugging in two situations where the integrity of the
kernel no longer is guaranteed: when oopsing and when hitting a
tainting-condition. The goal is to not get weird lockdep traces that don't
make sense or are otherwise undebuggable, to not waste time.
Lockdep assumes that the previous state it knows about is valid to operate,
which is why lockdep turns itself off after the first violation it reports,
after that point it can no longer make that assumption.
A kernel oops means that the integrity of the kernel compromised; in
addition anything lockdep would report is of lesser importance than the
oops.
All the tainting conditions are of similar integrity-violating nature and
also make debugging/diagnosing more difficult.
Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/panic.c | 2 ++
1 file changed, 2 insertions(+)
diff -puN kernel/panic.c~disable-lock-debugging-when-kernel-state-becomes-untrusted kernel/panic.c
--- a/kernel/panic.c~disable-lock-debugging-when-kernel-state-becomes-untrusted
+++ a/kernel/panic.c
@@ -172,6 +172,7 @@ const char *print_tainted(void)
void add_taint(unsigned flag)
{
+ debug_locks_off(); /* can't trust the integrity of the kernel anymore */
tainted |= flag;
}
EXPORT_SYMBOL(add_taint);
@@ -256,6 +257,7 @@ int oops_may_print(void)
*/
void oops_enter(void)
{
+ debug_locks_off(); /* can't trust the integrity of the kernel anymore */
do_oops_enter_exit();
}
_
Patches currently in -mm which might be from arjan@xxxxxxxxxxxxxxx are
origin.patch
improve-lockdep-debug-output.patch
lockdep-core-reduce-per-lock-class-cache-size.patch
put-a-comment-at-register_die_notifier-that-the-export-is-used.patch
git-acpi.patch
lockdep-annotate-8390c-disable_irq-2.patch
lockdep-fix-sk_dst_check-deadlock.patch
lockdep-split-the-skb_queue_head_init-lock-class.patch
fix-deadlock-in-the-bluetooth-l2cap-layer.patch
sleazy-fpu-feature-x86_64-support.patch
sleazy-fpu-feature-i386-support.patch
disable-lock-debugging-when-kernel-state-becomes-untrusted.patch
delay-accounting-taskstats-interface-send-tgid-once.patch
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