Simple prototype to enable might_sleep() checks in might_fault(), avoiding false
positives for scenarios involving explicit pagefault_disable().
So this should work:
spin_lock(&lock); /* also if left away */
pagefault_disable()
rc = copy_to_user(...)
pagefault_enable();
spin_unlock(&lock); /*
And this should report a warning again:
spin_lock(&lock);
rc = copy_to_user(...);
spin_unlock(&lock);
Still missing:
- Split of preempt documentation update + preempt_active define reshuffle
- Debug version to test for over/underflows
- Change documentation of user access methods to reflect the real behavior
- Don't touch the preempt counter, only the pagefault disable counter (future
work)
David Hildenbrand (2):
preempt: track pagefault_disable() calls in the preempt counter
mm, sched: trigger might_sleep() in might_fault() when pagefaults are
disabled
include/linux/kernel.h | 9 +++++++--
include/linux/preempt_mask.h | 24 +++++++++++++++++++-----
include/linux/uaccess.h | 21 ++++++++++++++-------
mm/memory.c | 15 ++++-----------
4 files changed, 44 insertions(+), 25 deletions(-)
--
1.8.5.5
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