diff options
| author | Waiman Long <longman@redhat.com> | 2020-01-15 10:43:36 -0500 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-01-17 10:19:27 +0100 |
| commit | 39e7234f00bc93613c086ae42d852d5f4147120a (patch) | |
| tree | 35f22309a78dc484ba8efa5602c58ee468955a9d | |
| parent | 51bfb1d11d6daf095addf9fe8471c20992caae0b (diff) | |
locking/rwsem: Fix kernel crash when spinning on RWSEM_OWNER_UNKNOWN
The commit 91d2a812dfb9 ("locking/rwsem: Make handoff writer
optimistically spin on owner") will allow a recently woken up waiting
writer to spin on the owner. Unfortunately, if the owner happens to be
RWSEM_OWNER_UNKNOWN, the code will incorrectly spin on it leading to a
kernel crash. This is fixed by passing the proper non-spinnable bits
to rwsem_spin_on_owner() so that RWSEM_OWNER_UNKNOWN will be treated
as a non-spinnable target.
Fixes: 91d2a812dfb9 ("locking/rwsem: Make handoff writer optimistically spin on owner")
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200115154336.8679-1-longman@redhat.com
| -rw-r--r-- | kernel/locking/rwsem.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 44e68761f432..0d9b6be9ecc8 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -1226,8 +1226,8 @@ wait: * In this case, we attempt to acquire the lock again * without sleeping. */ - if ((wstate == WRITER_HANDOFF) && - (rwsem_spin_on_owner(sem, 0) == OWNER_NULL)) + if (wstate == WRITER_HANDOFF && + rwsem_spin_on_owner(sem, RWSEM_NONSPINNABLE) == OWNER_NULL) goto trylock_again; /* Block until there are no active lockers. */ |