diff options
author | Alexei Starovoitov | 2019-02-10 21:52:35 +0100 |
---|---|---|
committer | Greg Kroah-Hartman | 2019-03-23 20:09:48 +0100 |
commit | c7c68a1b9a16e861d58c634c8462f6a72e317366 (patch) | |
tree | aaad6c2e71d50943b7af532acc16609f27f3b79d | |
parent | bpf: only adjust gso_size on bytestream protocols (diff) | |
download | kernel-qcow2-linux-c7c68a1b9a16e861d58c634c8462f6a72e317366.tar.gz kernel-qcow2-linux-c7c68a1b9a16e861d58c634c8462f6a72e317366.tar.xz kernel-qcow2-linux-c7c68a1b9a16e861d58c634c8462f6a72e317366.zip |
bpf: fix lockdep false positive in stackmap
[ Upstream commit 3defaf2f15b2bfd86c6664181ac009e91985f8ac ]
Lockdep warns about false positive:
[ 11.211460] ------------[ cut here ]------------
[ 11.211936] DEBUG_LOCKS_WARN_ON(depth <= 0)
[ 11.211985] WARNING: CPU: 0 PID: 141 at ../kernel/locking/lockdep.c:3592 lock_release+0x1ad/0x280
[ 11.213134] Modules linked in:
[ 11.214954] RIP: 0010:lock_release+0x1ad/0x280
[ 11.223508] Call Trace:
[ 11.223705] <IRQ>
[ 11.223874] ? __local_bh_enable+0x7a/0x80
[ 11.224199] up_read+0x1c/0xa0
[ 11.224446] do_up_read+0x12/0x20
[ 11.224713] irq_work_run_list+0x43/0x70
[ 11.225030] irq_work_run+0x26/0x50
[ 11.225310] smp_irq_work_interrupt+0x57/0x1f0
[ 11.225662] irq_work_interrupt+0xf/0x20
since rw_semaphore is released in a different task vs task that locked the sema.
It is expected behavior.
Fix the warning with up_read_non_owner() and rwsem_release() annotation.
Fixes: bae77c5eb5b2 ("bpf: enable stackmap with build_id in nmi context")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r-- | kernel/bpf/stackmap.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 6a32933cae4f..7cb7a7f98a37 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -44,7 +44,7 @@ static void do_up_read(struct irq_work *entry) struct stack_map_irq_work *work; work = container_of(entry, struct stack_map_irq_work, irq_work); - up_read(work->sem); + up_read_non_owner(work->sem); work->sem = NULL; } @@ -338,6 +338,12 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, } else { work->sem = ¤t->mm->mmap_sem; irq_work_queue(&work->irq_work); + /* + * The irq_work will release the mmap_sem with + * up_read_non_owner(). The rwsem_release() is called + * here to release the lock from lockdep's perspective. + */ + rwsem_release(¤t->mm->mmap_sem.dep_map, 1, _RET_IP_); } } |