There are 3 RCU-based object iteration loops in kmemleak_scan(). Because
of the need to take RCU read lock, we can't insert cond_resched() into
the loop like other parts of the function. As there can be millions of
objects to be scanned, it takes a while to iterate all of them. The
kmemleak functionality is usually enabled in a debug kernel which is
much slower than a non-debug kernel. With sufficient number of kmemleak
objects, the time to iterate them all may exceed 22s causing soft lockup.
watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [kmemleak:625]
This patch series make changes to the 3 object iteration loops in
kmemleak_scan() to prevent them from causing soft lockup.
Waiman Long (3):
mm/kmemleak: Use _irq lock/unlock variants in kmemleak_scan/_clear()
mm/kmemleak: Skip unlikely objects in kmemleak_scan() without taking
lock
mm/kmemleak: Prevent soft lockup in first object iteration loop of
kmemleak_scan()
mm/kmemleak.c | 52 ++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 41 insertions(+), 11 deletions(-)
--
2.31.1
