On Mon, Aug 23, 2021 at 04:54:16PM +0000, Haakon Bugge wrote: > > > > On 8 Jul 2020, at 03:12, Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > > > > On Tue, Jul 07, 2020 at 06:05:02PM -0700, Divya Indi wrote: > >> Thanks Jason. > >> > >> Appreciate your help and feedback for fixing this issue. > >> > >> Would it be possible to access the edited version of the patch? > >> If yes, please share a pointer to the same. > > > > https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/commit/?h=for-rc&id=f427f4d6214c183c474eeb46212d38e6c7223d6a > > Hi Jason, > > > At first glanse, this commit calls rdma_nl_multicast() whilst > holding a spinlock. Since rdma_nl_multicast() is called with a > gfp_flag parameter, one could assume it supports an atomic > context. rdma_nl_multicast() ends up in > netlink_broadcast_filtered(). This function calls > netlink_lock_table(), which calls read_unlock_irqrestore(), which > ends up calling _raw_read_unlock_irqrestore(). And here > preempt_enable() is called :-( I don't understand. This: unsigned long flags; read_lock_irqsave(&nl_table_lock, flags); atomic_inc(&nl_table_users); read_unlock_irqrestore(&nl_table_lock, flags); Is perfectly fine in an atomic context. preempt_enable is implemented as a nesting counter, so it is fine to call it from inside an atomic region so long as it is balanced. Jason
